Solving one of nature's great puzzles: What drives the accelerating expansion of the universe?

May 15, 2017
Credit: NASA

UBC physicists may have solved one of nature's great puzzles: what causes the accelerating expansion of our universe?

PhD student Qingdi Wang has tackled this question in a new study that tries to resolve a major incompatibility issue between two of the most successful theories that explain how our universe works: and Einstein's theory of .

The study suggests that if we zoomed in-way in-on the universe, we would realize it's made up of constantly fluctuating space and time.

"Space-time is not as static as it appears, it's constantly moving," said Wang.

"This is a new idea in a field where there hasn't been a lot of new ideas that try to address this issue," said Bill Unruh, a physics and astronomy professor who supervised Wang's work.

In 1998, astronomers found that our universe is expanding at an ever-increasing rate, implying that space is not empty and is instead filled with dark that pushes matter away.

The most natural candidate for dark energy is . When physicists apply the theory of quantum mechanics to vacuum energy, it predicts that there would be an incredibly large density of vacuum energy, far more than the total energy of all the particles in the universe. If this is true, Einstein's theory of general relativity suggests that the energy would have a strong gravitational effect and most physicists think this would cause the universe to explode.

Fortunately, this doesn't happen and the universe expands very slowly. But it is a problem that must be resolved for fundamental physics to progress.

Unlike other scientists who have tried to modify the theories of quantum mechanics or general relativity to resolve the issue, Wang and his colleagues Unruh and Zhen Zhu, also a UBC PhD student, suggest a different approach. They take the large density of vacuum energy predicted by quantum mechanics seriously and find that there is important information about vacuum energy that was missing in previous calculations.

Their calculations provide a completely different physical picture of the universe. In this new picture, the space we live in is fluctuating wildly. At each point, it oscillates between expansion and contraction. As it swings back and forth, the two almost cancel each other but a very small net effect drives the to expand slowly at an accelerating rate.

But if space and time are fluctuating, why can't we feel it?

"This happens at very tiny scales, billions and billions times smaller even than an electron," said Wang.

"It's similar to the waves we see on the ocean," said Unruh. "They are not affected by the intense dance of the individual atoms that make up the water on which those waves ride."

Their paper was published last week in Physical Review D: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.95.103504.

Explore further: Quest to settle riddle over Einstein's theory may soon be over

More information: Qingdi Wang et al, How the huge energy of quantum vacuum gravitates to drive the slow accelerating expansion of the Universe, Physical Review D (2017). DOI: 10.1103/PhysRevD.95.103504

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221 comments

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HannesAlfven
2.4 / 5 (10) May 15, 2017
Re: "The most natural candidate for dark energy is vacuum energy ... In this new picture, the space we live in is fluctuating wildly. At each point, it oscillates between expansion and contraction. As it swings back and forth, the two almost cancel each other but a very small net effect drives the universe to expand slowly at an accelerating rate ... This happens at very tiny scales, billions and billions times smaller even than an electron"

There is a sense about this that they are GUESSING.
Zzzzzzzz
4.1 / 5 (9) May 15, 2017
So their calculations show that spacetime vibrates between expansion and contraction, with a bias toward expansion. How is the expansion accelerating? Does the fluctuation progress toward a greater bias toward expansion, or is there a constant rate of bias that accumulates? Like most Phys.org articles, very little detail....
Whydening Gyre
3 / 5 (4) May 15, 2017
FTA;
"It's similar to the waves we see on the ocean," said Unruh. "They are not affected by the intense dance of the individual atoms that make up the water on which those waves ride."

Sounds like Zeph may have been onto something...:-)

Gigel
5 / 5 (5) May 15, 2017
Link to article: https://arxiv.org...03.00543

Sorry, RNP :)
Steelwolf
1 / 5 (2) May 15, 2017
It may also be that the Expansion that we are able to see is actually only a 'local' effect, that other parts of the universe may be contracting, such as near high mass objects.
rogerdallas
4.2 / 5 (5) May 15, 2017
This article is talking about activity at extremely small scales-- nearly infinitesimal dimensions. I wonder sometimes whether at such scales, space and time dimensions might all be "hyperbolic" and be exchangeable in the same way. The unification would be pleasing, and right off the top of my head, it seems that it would be easier to achieve unification of QM and GR and explain some perplexing features of the universe at large. I think the fluctuations mentioned in the article would then emerge naturally, as well as the bias toward expansion.
Dingbone
May 15, 2017
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Dingbone
May 15, 2017
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Dingbone
May 15, 2017
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Dingbone
May 15, 2017
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baudrunner
1 / 5 (3) May 15, 2017
But if space and time are fluctuating, why can't we feel it?
Obviously, because we are fluctuating with it, all things being relative. It's not like we are standing outside of space/time, just because we can talk about it.

Just an idea (ideas aren't pseudoscience - we're allowed to have 'em), but what if everything, and everything that everything is made of, is shrinking all the time - atomic diameters getting smaller and smaller with time. How long can that go on before this process encounters some quantum threshold?
dnatwork
not rated yet May 15, 2017
...what if everything, and everything that everything is made of, is shrinking all the time - atomic diameters getting smaller and smaller with time.


That idea has been around since at least the 1930's, but I think it's framed wrong. What if you and I and everything else are not shrinking, but our reference frames are? They theorize in terms of inertial reference frames, but then they worry about contraction and expansion, and go off and invent vacuum energy.

If space has energy and structure, then it should push back on everything in a gravity well, stopping it from getting deeper when the mass reaches equilibrium with the stiffness of space itself (rubber sheet analogy). If space is nothing, then gravity wells should keep getting deeper forever. In that case, two wells that are close should form a common well over time (dark matter), and distant wells should gradually get farther apart (dark energy).

No quantum limit because nobody shrank, just appeared to from afar.
dnatwork
not rated yet May 15, 2017
...what if everything, and everything that everything is made of, is shrinking all the time - atomic diameters getting smaller and smaller with time.


That idea has been around since at least the 1930's, but I think it's framed wrong. What if you and I and everything else are not shrinking, but our reference frames are? They theorize in terms of inertial reference frames, but then they worry about contraction and expansion, and go off and invent vacuum energy.

If space has energy and structure, then it should push back on everything in a gravity well, stopping it from getting deeper when the mass reaches equilibrium with the stiffness of space itself (rubber sheet analogy). If space is nothing, then gravity wells should keep getting deeper forever. In that case, two wells that are close should form a common well over time (dark matter), and distant wells should gradually get farther apart (dark energy).

No quantum limit because nobody shrank, just appeared to from afar.
Dingbone
May 15, 2017
This comment has been removed by a moderator.
billpress11
1 / 5 (5) May 15, 2017
Another observation, along with the observed flatness, that just doesn't quite square with the BB theory. Notice in the quote below the brightness of the type 1a supernova doesn't fit the observed brightness at great distances. There is another explanation, the distance measurements could be wrong.

Quote from link below:

"The accelerated expansion was discovered in 1998, when two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team simultaneously obtained results suggesting an acceleration in the expansion of the universe by using distant type Ia supernovae as standard candles."[5][6][7

https://en.wikipe...universe

rrwillsj
1 / 5 (2) May 15, 2017
Aside from clickbait headlines (yep, got my attention!)

I would opinion, that based on all the hypothetical commentaries that follow these articles of imminent total universal scientific comprehension.

Promising, with just a little more funding? All questions will finally be answered beyond all possible disagreement.

And we can all smugly bask in the glory of our awesome genius.

However, 'Science' is an eternally continuous and infinite process rife with incomplete information of splendiferous contradictions and questionable speculations.

Hey! That's what makes Science fun!
brodix
1 / 5 (1) May 15, 2017
It makes sense and it doesn't just happen at subatomic scales. Space contracts into galaxies and expands between them and it does balance out. That is why space appears flat on the largest scales, because it is.
Basically a cosmic convection cycle, of radiation expanding and mass/gravity collapsing.
(Keeping in mind the measures of space contracting are based on mass/gravity and the observations of space expanding are of light/radiation.)
jsdarkdestruction
not rated yet May 15, 2017
it predicts that there would be an incredibly large density of vacuum energy, far more than the total energy of all the particles in the universe. If this is true, Einstein's theory of general relativity suggests that the energy would have a strong gravitational effect and most physicists think this would cause the universe to explode

I am having difficulty understanding how this works. How would this cause the universe to explode?
Da Schneib
not rated yet May 15, 2017
Wow, lots of hyperbole in this article.

Interesting idea, but not the solution to quantum gravity. At least not the way it's stated here. Now to go read the paper... thanks @Gigel.
Seeker2
1 / 5 (1) May 15, 2017
I think explosion is exactly the right word as long as there is a constant dark energy for spacetime to feed on wherever it expands. That is, apparently, everywhere inside and outside the observable U. We just happen to get in on the early phase.
Seeker2
3.3 / 5 (3) May 15, 2017
@Zzzz
So their calculations show that spacetime vibrates between expansion and contraction, with a bias toward expansion. How is the expansion accelerating? Does the fluctuation progress toward a greater bias toward expansion, or is there a constant rate of bias that accumulates? Like most Phys.org articles, very little detail....
Every time spacetime expands it admits more dark energy causing even more oscillations (actually uncertainty). Called exponential expansion.
Seeker2
1 / 5 (1) May 15, 2017
"incredibly large density of vacuum energy, far more than the total energy of all the particles in the universe. If this is true, Einstein's theory of general relativity suggests that the energy would have a strong gravitational effect and most physicists think this would cause the universe to explode."

Sure seems that way. However you would get no strong gravitational effect. That comes only with a gradient in the energy of this explosion. Nature does that with quantized energy. That is quantized matter consists of a fixed amount of spacetime which misses out on all the expansion. It has no way to resist the expanding spacetime so it gets the squeeze. Called gravity.
Seeker2
3.7 / 5 (3) May 15, 2017
@Steelwolf
It may also be that the Expansion that we are able to see is actually only a 'local' effect, that other parts of the universe may be contracting, such as near high mass objects.
I don't see any local expansion, only between galaxies. High mass objects are being collected by gravity, as in black holes, but contracted, I don't know. Maybe only forming a denser object.
someone11235813
not rated yet May 16, 2017
Does this mean we are closer to a quantum field theory of gravity? Or it is just a new hypothesis of the mechanism of the acceleration of the expansion of the universe?
Seeker2
1 / 5 (1) May 16, 2017
Could be both.
Seeker2
3 / 5 (2) May 16, 2017
I'm lost when they talk about the gravitational property of the quantum vacuum. I did find my library card though. A 14 digit number. Maybe someday.
Ojorf
3.7 / 5 (3) May 16, 2017
Guys this is not about quantum gravity or any unification theory.
It basically means (it true) that the quantum fluctuations at incredibly minute scales (always predicted by QD), also include expansions and contractions of spacetime, with their math suggesting a bias toward expansion via SR.
The idea seems so simple and logical I hope the math all pans out.
This is great, why wouldn't the "quantum foam" include shrinkings and stretchings?
Could be one of those things that in retrospect seem totally logical, why didn't someone think to explore this earlier?
Well done.
Da Schneib
4.2 / 5 (5) May 16, 2017
@Ojorf, yes, that's correct, it's not about unification or quantum gravity, though it does open the door a crack to give some ideas of what quantum gravity must look like. As for why no one did this before, I'd say the math in this paper explains why; this is a real brain-burner. Whether it turns out to be elegant or not remains to be seen.

It's a very good idea, and marvelously well developed. Checking the math will be a huge project, and likely take a long time to happen. But this looks like a viable explanation for the huge difference between the predictions of cosmological constant by QM and GR/observation.

I will have to absorb this for a while more and then reflect upon it before I start to see other implications. But I estimate this should give the pot a pretty big stir in gravity physics.
Da Schneib
4.3 / 5 (6) May 16, 2017
I have to say this is a very, very interesting paper. My mind is in a ferment considering it. I expect to be thinking about this for a long time to come. I suppose that should be no surprise from a student of Unruh.
Dingbone
May 16, 2017
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Dingbone
May 16, 2017
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Old_C_Code
3.4 / 5 (5) May 16, 2017
FYI: The space within galaxies is NOT expanding. It's the galaxies themselves expanding away from one another.
Mimath224
5 / 5 (2) May 16, 2017
@Da Schneib I had a look at the abstract but cannot access the main article...can you help? Use private message if you wish. What took my eye was the 10^-120 figure mentioned. I find the article intriguing although I do think this is not the first on proposing a fluctuating space-time although I can't remember where I read it...must have been a couple of years ago. I wonder if this is like a 'super-duper-string theory', since vibrating strings expand and contract, except it would be at a more fundamental level. That is, are SS composed of strings themselves?
Kron
not rated yet May 16, 2017
I had a look at the abstract but cannot access the main article...can you help?

Is the *PDF* download not working for you?
Dingbone
May 16, 2017
This comment has been removed by a moderator.
Seeker2
not rated yet May 16, 2017
@Dingbone Got a link?
swordsman
1 / 5 (2) May 16, 2017
Space and time do not vary. That mistake dates back to Einstein and Minkowski. Minkowski improperly interpreted the radiation equation, and Einstein accepted it. It is not space and time that vary in accordance with the Minkowski equation. That equation occurs directly in the radiation equation of a radio antenna. It is the electromagnetic radiation field that varies in accordance. This should have been solved 80 years ago, since the measurements of radiation support it.
snoosebaum
5 / 5 (1) May 16, 2017
Is there an implication here that these tiny fluctuations give rise to particles ?
Da Schneib
5 / 5 (2) May 16, 2017
@Mimath, just use @Gigel's link.
Ojorf
5 / 5 (2) May 17, 2017
Is there an implication here that these tiny fluctuations give rise to particles ?


Yes they do, see: https://en.wikipe...ctuation
Mimath224
5 / 5 (2) May 17, 2017
@Da Schneib Yes I had tried and the link given in the article itself. The latter requires having an account, which I haven't, and the former would not download. However, trying the former again today I have got the PDF on the third attempt. The former attempts resulted in diagrams and equations being superimposed upon one another which does happen on other downloads too. Anyway, thanks and to Gigel too.
I'll be comparing 'notes' with the CEM tensor and the various Friedmann Walker etc. models but as a layman it will need some determined effort.
@Dingbone
'@Kron: Preprint - but in my experience the people who cannot find source info themselves aren't intelligent enough for to understand it anyway.'
Your experience must be very limited then!

Whydening Gyre
5 / 5 (3) May 17, 2017
I wonder if this is like a 'super-duper-string theory', since vibrating strings expand and contract, except it would be at a more fundamental level. That is, are SS composed of strings themselves?

Ones that spin..:-)
Mimath224
5 / 5 (2) May 18, 2017
@Whydening Gyre Oh yeah I always like a 'spin' on things so that I can see who 's trying to 'hang on' there, Ha! But at 10^-120 would there be too much space or not enough?
xinhangshen
1 / 5 (3) May 18, 2017
Please be aware that Einstein's relativity theory has already been disproved both logically and experimentally (see "Challenge to the special theory of relativity", March 1, 2016).

The most obvious and indisputable experimental evidence, which everybody with basic knowledge of special relativity should immediately understand: is the existence of the absolute time shown by the universally synchronized clocks on the GPS satellites which move at high velocities relative to each other while special relativity claims that time is relative (i.e. the time on each reference frame is different) and can never be synchronized on clocks moving with relative velocities.
Da Schneib
5 / 5 (2) May 18, 2017
An interesting part of this is that this math may represent a point of attack for linking gravity physics to macroscopic phenomena, if anyone can get their head around it. These oscillating patches of spacetime foam may actually be the strings of string physics, or the loops of LQG.
Mimath224
5 / 5 (2) May 18, 2017
@xinhangshen You might be in for a rough here but i'll let others argue the point. This should be fun. Just to start things off, I understood that GR plays a greater role than SR in GPS etc. especially when considering that satellite experience differing gravitational values during their path...maybe you are just advertising your paper? You might also clarify where your quote is relevant to the present article, which my, as yet brief, perusal of the main paper doesn't mention SR.
xinhangshen
1 / 5 (2) May 18, 2017
@xinhangshen You might be in for a rough here but i'll let others argue the point. This should be fun. Just to start things off, I understood that GR plays a greater role than SR in GPS etc. especially when considering that satellite experience differing gravitational values during their path...maybe you are just advertising your paper? You might also clarify where your quote is relevant to the present article, which my, as yet brief, perusal of the main paper doesn't mention SR.


My original post was much longer, but the website cuts off the other part. Yes, the article is closely related to SR. I have disproved SR and confirmed that time is absolute and there is no such a thing called 4D spacetime continuum in nature. Therefore, GR is also disproved, and so are the existences of dark matter and dark energy which are introduced as patches of general relativity.

I will also be glad to debate with you and all other interested people about clocks on GPS.
xinhangshen
1 / 5 (2) May 18, 2017
Many physicists claim that clocks on the GPS satellites are corrected according to both special relativity and general relativity. This is not true. The corrections of the atomic clocks on the GPS satellites are nothing to do with relativistic effects because the corrections are absolute changes of the clocks, none of which is relative as claimed by special relativity. After all corrections, the clocks are synchronized not only relative to the ground clocks but also relative to each other.
xinhangshen
1 / 5 (2) May 18, 2017
Some people may argue that the clocks are only synchronized in the earth centered inertial reference frame, and are not synchronized in the reference frames of the GPS satellites. If it were true, then the time difference between a clock on a GPS satellite and a clock on the ground observed in the satellite reference frame would grow while the same clocks observed on the earth centered reference frame were keeping synchronized. If you corrected the clock on the satellite when the difference became significant, the correction would break the synchronization of the clocks observed in the earth centered frame. That is, there is no way to make a correction without breaking the synchronization of the clocks observed in the earth centered frame. Therefore, it is wrong to think that the clocks are not synchronized in the satellite frame.
xinhangshen
1 / 5 (2) May 18, 2017
Actually, on my paper mentioned above, I have proved that if clocks are synchronized in one inertial reference frame, then they are synchronized in all inertial reference frames because clock time is absolute and universal.
Whydening Gyre
5 / 5 (3) May 18, 2017
@Whydening Gyre Oh yeah I always like a 'spin' on things so that I can see who 's trying to 'hang on' there, Ha! But at 10^-120 would there be too much space or not enough?


Since it is Space that is spinning - exactly the right amount...:-)
But...
At that size, does centripetal/centrifugal even apply?
(Not to mention that it is space (nothing) doing the spinning...)

And I'm thinkin'....
A 'string' is a serial collection of points. What keeps them aligned into a string...?
Could it possibly be direction of motion in a particular vector?
(If that is the case, then they should be called Directions, not Dimensions...)
Seeker2
5 / 5 (1) May 18, 2017
@DS
An interesting part of this is that this math may represent a point of attack for linking gravity physics to macroscopic phenomena, if anyone can get their head around it. These oscillating patches of spacetime foam may actually be the strings of string physics, or the loops of LQG.
I'm thinking these oscillations trap dark energy leading to gravity and the exponential growth of spacetime. On the micro level these oscillations may be trapped and synchronized to mediate forces such as the strong force.
antialias_physorg
5 / 5 (7) May 18, 2017
Actually, on my paper mentioned above, I have proved that if clocks are synchronized in one inertial reference frame, then they are synchronized in all inertial reference frames because clock time is absolute and universal.

And yet we have already done experiments with actual clocks that show it's not as you say.

Reality trumps thousands and thousands of pages of theory any day.
Whydening Gyre
5 / 5 (2) May 18, 2017
Some people may argue that the clocks are only synchronized in the earth centered inertial reference frame, and are not synchronized in the reference frames of the GPS satellites. If it were true, then the time difference between a clock on a GPS satellite and a clock on the ground observed in the satellite reference frame would grow while the same clocks observed on the earth centered reference frame were keeping synchronized. If you corrected the clock on the satellite when the difference became significant, the correction would break the synchronization of the clocks observed in the earth centered frame. That is, there is no way to make a correction without breaking the synchronization of the clocks observed in the earth centered frame. Therefore, it is wrong to think that the clocks are not synchronized in the satellite frame.

Isn't that what recalibration is? A re-sync of the collection of clocks? Regardless of "frame"?
Whydening Gyre
5 / 5 (5) May 19, 2017
Actually, on my paper mentioned above, I have proved that if clocks are synchronized in one inertial reference frame, then they are synchronized in all inertial reference frames because clock time is absolute and universal.

Only if their velocity is "synchronized" as well (not to mention - their position relative to any other massive body{s})
idjyit
4.3 / 5 (6) May 19, 2017
@xinhangshen
This might help you understand why the clocks on earth don't stay synchronised ...
https://en.wikipe...of_Earth
Mimath224
5 / 5 (3) May 20, 2017
@idjyit yes, this was basically my point to xhs when I mentioned satellites; my problem was/is that if know about such...and I'm a layman...I thought someone who says 'he can prove' this & that, would surely realize this too.
Dingbone
May 20, 2017
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Dingbone
May 20, 2017
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Dingbone
May 20, 2017
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xinhangshen
1 / 5 (1) May 20, 2017
Actually, on my paper mentioned above, I have proved that if clocks are synchronized in one inertial reference frame, then they are synchronized in all inertial reference frames because clock time is absolute and universal.

And yet we have already done experiments with actual clocks that show it's not as you say.

Reality trumps thousands and thousands of pages of theory any day.


It's true that reality is the king. But we must understand reality correctly. As I pointed out, the interpretation of the corrections of the clocks as relativistic effects is wrong. I never deny that clocks need corrections just like your watch that need corrections too because there are many factors can influence the accuracy of the atomic clocks. But none of these corrections is observer dependent correction as claimed by special relativity because the corrections are absolute.
idjyit
4.2 / 5 (5) May 20, 2017
@xinhangshen
I have no idea what your on about...
"Einstein's general relativity theory says that gravity curves space and time, resulting in a tendency for the orbiting clocks to tick slightly faster, by about 45 microseconds per day. The net result is that time on a GPS satellite clock advances faster than a clock on the ground by about 38 microseconds per day."
http://physicscen...will.cfm

For this reason the satellites clocks are designed to run "slow", because of empirical observation.
Ground control stations also monitor and update a satellites time as well as other navigational data, at least once a day.

Because a GPS receiver ("Observer") has no idea when the satellite sent it's signal it relies intrinsically on its internal clock for distance calculations, if the clocks on the ground aren't synchronised with the clock in the satellites you would have ever increasing errors in the calculations.
ZergSurfer
3.7 / 5 (6) May 20, 2017
" ...there are many factors can influence the accuracy of the atomic clocks."
Name them. Deny Doppler. I dare you.
(He realised things were different for observers moving relative to each other)
(GPS satellites are not in geosynchronous orbit, but a fast orbiting net)
:)
Da Schneib
5 / 5 (4) May 20, 2017
" ...there are many factors can influence the accuracy of the atomic clocks."
Wow, who idiotically claimed that? The entire point of atomic clocks is to be an absolutely locally accurate time reference; our actual reference of time, the SI definition of the second, is based on them. Specifically, the "second" is defined as exactly 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.

Here we have someone arguing about the definition of a second. Good luck with that.
Seeker2
not rated yet May 20, 2017
...the "second" is defined as exactly 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
So what happens at 1g?
Da Schneib
not rated yet May 21, 2017
...the "second" is defined as exactly 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom.
So what happens at 1g?

@Seeker, nothing different.

That's the point, see.
Seeker2
not rated yet May 21, 2017
So now my sea level laboratory cesium standard located on the equator is rotating around the earth's axis once every 24 hours along with most everyone else. Anything happen here?
Seeker2
not rated yet May 21, 2017
So now my cesium standard is free falling in orbit at 0g, I presume. Anything happen to the transition frequency now?
Da Schneib
not rated yet May 21, 2017
So now my sea level laboratory cesium standard located on the equator is rotating around the earth's axis once every 24 hours along with most everyone else. Anything happen here?
Where are you looking from? This is a very important question if you are dealing with any kind of relativity.
Seeker2
not rated yet May 21, 2017
You mean the laws of physics depend on where you're looking from?
Da Schneib
not rated yet May 21, 2017
No, I mean that what you observe is affected by the laws of physics, and those alter what you observe depending on where you are, what you're doing, and where what you're observing is and what it's doing, compared with someone who's local to what you're observing.

You can only see things with light, and if gravitation alters the propagation of light compared with its propagation in flat space, then you can expect what you see to be altered by gravitation. And BTW, that's also true for simple velocity; relativity of simultaneity shows that.
Seeker2
not rated yet May 21, 2017
Gravitation and flat space don't get along too well.
Da Schneib
not rated yet May 21, 2017
Yep. That's why stars observed close to the Sun during an eclipse appear to be in different positions than when they're far from it.
Mimath224
5 / 5 (2) May 21, 2017
@idjyit & Da Schneib with regard @xinhangshen. Well, I did say in my first post that 'this is going to be fun'. Actually @xinhangshen is quoting from his paper extract which can be found at http://proceeding...=2441853
Since I am not a member SPIE I cannot access the main paper from volume 9570. according to the abstract SR is wrong and any consequences of SR are also (this is not an actual quote but an interpretation of what is written there).
Seeker2
not rated yet May 21, 2017
Gravitation and flat space don't get along too well.
The solution to this little quandary is to define the transition frequency in flat space. But my laboratory is not in flat space. So what would be the actual transition frequency that I observe in my lab?
Da Schneib
5 / 5 (5) May 21, 2017
@Mimath, I have no time for relativity cranks. SR has massive experimental corroboration. High school kids do relativity experiments for science fairs and reproduce the expected results.

On another thread it has been pointed out that this individual's claims directly contradict the Hafele-Keating experiment performed in 1971. It's the one where they took cesium clocks on airplanes; I'm sure you've heard of that.

Having checked, it appears that this individual has neglected to note that time is not invariant under the Lorentz coordinate transformation. And that only one transformation can be applied at one time. These are basic errors.

It's unfortunate that the SPIE doesn't peer-review all its publications. If this individual had actually proven SRT is incorrect in 2015, it would be in all the newspapers.
Da Schneib
not rated yet May 21, 2017
@Seeker unless your lab is close enough to a neutron star or black hole to be spaghettified by the gravity and roasted post-well-done by the radiation, you don't need to account for GRT in your lab.
idjyit
5 / 5 (3) May 21, 2017
@Mimath224 since he/she is not willing to elaborate except to repeat his initial statements, we'll just have to disagree and let it go at that.
Seeker2
1 / 5 (1) May 21, 2017
That's why stars observed close to the Sun during an eclipse appear to be in different positions than when they're far from it.
So the laws of physics apply to any observer in the right position. If you're not in the right position to make the observation this doesn't mean the laws of physics are observer dependent.
Da Schneib
5 / 5 (2) May 21, 2017
@Mimath, I'l waste a little more time on this.

First I was absolutely not kidding in any way about kids doing Science Fair projects proving relativity: Michelson-Morley is a common test.

Second, Hafele-Keating has been repeated many times by satellites, most recently in Gravity Probes A and B.

And I was unfortunately not kidding at all about the non-peer-reviewed status of the Proceedings of the SPIE. Hopefully they do better in their technical journals of record.

Seeker2
not rated yet May 21, 2017
@Seeker unless your lab is close enough to a neutron star or black hole to be spaghettified by the gravity and roasted post-well-done by the radiation, you don't need to account for GRT in your lab.
Interesting. No need to account for gravity with orbiting clocks. At least cesium standards. They should be glad to hear that.
Da Schneib
5 / 5 (2) May 21, 2017
That's why stars observed close to the Sun during an eclipse appear to be in different positions than when they're far from it.
So the laws of physics apply to any observer in the right position. If you're not in the right position to make the observation this doesn't mean the laws of physics are observer dependent.

I don't understand why you think relativity isn't part of the Laws of Physics. I assure you it is accepted to that level by the general physics community.

No need to account for gravity with orbiting clocks.
Not if you're local to the clock. If you're not, then lots of need.
Da Schneib
not rated yet May 21, 2017
I'll point out, @Seeker, that unless your lab is a couple hundred miles high and stretches around the world, it doesn't include any satellites.
Seeker2
not rated yet May 21, 2017
I don't understand why you think relativity isn't part of the Laws of Physics.
If it is then best use it.
No need to account for gravity with orbiting clocks.
Not if you're local to the clock. If you're not, then lots of need.
Well I'm not so let's use it.
Da Schneib
not rated yet May 21, 2017
OK, so that means you have to use relativity to figure both the gamma and the gravity.

Which means you'll have to account both for velocity and gravity.

Weren't you just saying you didn't have to account for gravity? Looks like that was wrong.

Seeker2
1 / 5 (1) May 21, 2017
Forget gamma for the moment. Let's recap. The standard is defined for flat space. I'm not in flat space so what should my standard read?
Da Schneib
5 / 5 (1) May 21, 2017
@Seeker, you're in space so close to flat that very weak gravity doesn't have any effect, locally. It's orders of magnitude below our ability to measure locally.

I been tryin' to tell you that for about five posts now.
Dingbone
May 21, 2017
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Dingbone
May 21, 2017
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Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
@Dingbat, please restrict your comments recognizing that there are people here who understand relativity and quantum mechanics far better than you do, demonstrably given the weird and wild and woolly statements you have made demonstrating your abysmal ignorance of relativity and quantum mechanics.

As an example: "low-dimensional models." Quantum mechanics uses dimensions to describe scores of quantum parameters you have never even heard of. This is perhaps the silliest thing I've heard anyone say in the last week, and I have dealt with a #climatecrank who pretended heat could be dissipated in an open vacuum by convection, and someone who thinks that they can make a laboratory a couple hundred miles high stretching around the Earth.

I strongly recommend you do not demonstrate your ignorance further but instead remain quiet and see if you can learn some real physics.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
Wow, looks like @Dingbat is drunkposting.

Either that or coffeeposting.

Look dude nobody cares about your manifesto. Either you have specific statements you can prove or not; posting word salad doesn't help, it just makes you look like a nutjob.
Dingbone
May 21, 2017
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Da Schneib
not rated yet May 21, 2017
@Dingbat
The understanding of things is based on finding common aspects
No, it's not. The understanding of things is based on the ability to accurately describe their behavior, and you cannot.

When you are compared with those who can it's apparent you have no idea what you're talking about; you're making meaningless comparisons between things that don't have anything to do with one another.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
LOL, @Dingbat, there is no numeric regression; this is about understanding how things work. You either can or cannot describe and predict how thing behave; if you cannot you are full of sxxt. Simple as that. And you cannot. If you could you would be and you aren't. Instead you have a bunch of excuses about why you cannot. It's transparent to a 3-year-old child.
Dingbone
May 21, 2017
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Seeker2
not rated yet May 21, 2017
@Seeker, you're in space so close to flat that very weak gravity doesn't have any effect, locally. It's orders of magnitude below our ability to measure locally.

I been tryin' to tell you that for about five posts now.

So why do they define it for flat space? Why correct clocks for gravity anyway? Who needs general relativity?
Da Schneib
5 / 5 (2) May 21, 2017
If so, why we aren't using epicycle models anymore?
Because they couldn't accurately describe the movements of the planets. Partial explanation is insufficient; complete explanation is mandatory.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (2) May 21, 2017
@Seeker, you're in space so close to flat that very weak gravity doesn't have any effect, locally. It's orders of magnitude below our ability to measure locally.

I been tryin' to tell you that for about five posts now.

So why do they define it for flat space? Why correct clocks for gravity anyway? Who needs general relativity?

Because details matter. And if you ignore GRT your GPS gives a position that's way off.
Da Schneib
5 / 5 (1) May 21, 2017
Well, you cannot explain, why the gravity follows the inverse square law and how the magnets are working
How do you know? Have you asked me?

I can explain the inverse square law quite simply: the surface area of a sphere increases as the square of its diameter. The total flux of a force must be evenly divided over the surface at any diameter. Any remaining questions about the inverse square law, or are you admitting you're too stupid to understand basic math?

Would you like to discuss magnets now, so I can make a further fool of you?
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
Pro Tip™: Don't assert someone can't explain something when you haven't asked if they can explain it. You are inviting them to make you look stupid.

Pro Tip™: Don't try to change the subject when you make up a lie claiming someone can't explain something and they explain it. It makes you look like a complete idiot. Or a @Dingbat.
Dingbone
May 21, 2017
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Mimath224
5 / 5 (2) May 21, 2017
@Da Schneib
@Mimath, I'l waste a little more time on this.
First I was absolutely not kidding.....
Second, Hafele-Keating has been repeated many times by satellites...
And I was unfortunately not kidding at all about the non-peer-reviewed status of the Proceedings of the SPIE. Hopefully they do better in their technical journals of record.

Apart from knowing absolutely nothing about SPIE journals (think this is my first encounter on the net) I am with you on this. I was trying to get to the full paper so that I could see the equations and thought if I couldn't someone here might. As you might remember I have ideas about Time, but they certainly don't conflict with SR or GR. I do agree we should not waste more time with xinhangshen.
But you might help me with Dingbone comment '...They apply to seemingly "large" but apparently "empty" areas of observable Universe...'?????? Other comments are equally...or do I bin my GR books?
Da Schneib
5 / 5 (1) May 21, 2017
Ummm, @Dingbat, you haven't addressed either the fact that you claimed I couldn't explain the inverse square law, and I successfully explained it, or magnets. You still look like an idiot and I'm rapidly coming to the conclusion you are, in fact, an idiot. Either that or a nutjob. I suggest you start explaining why math is wrong, or find somewhere else to post where everyone doesn't know you're an idiot.
Da Schneib
5 / 5 (1) May 21, 2017
@Mimath, after watching @Dingbat claim I couldn't explain the inverse square law and watching me explain it, I'm surprised you're even asking about anything this idiot claims. I really do suggest you not bother with people who make claims, get them disproven, and then try to change the subject. It's really pretty probitive.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
@Dingbat, you lied:
I already addressed it
No, you didn't. You claimed I couldn't explain it and I did. You haven't refuted it, and that's that.

If you want an explanation why gravity follows it, it's because it works in 3D space, which is what spheres exist in. That's why I used a sphere in my proof, duhhh ummm. If this is too difficult for you to follow you are not smart enough to understand physics.

Now stop lying.
Da Schneib
5 / 5 (1) May 21, 2017
Let me put it in terms a child could follow.

There is a certain amount of gravity for a given object.
Gravity works across space.
The farther from the object, the bigger the surface area of the sphere it must work over.
The surface area increases as the square of the radius of the sphere.
Therefore, the strength of the gravity decreases as the square of the radius.

Duuuuuuuuuhhhhhhhhhhhhhhhh ummmmmmmmmmmmmmmmmmmm.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
@Dingbat, there are no subtleties. This is extremely straightforward, easy, simple, and obvious to anyone who has the most basic training in mathematics.

I'm sorry you can't follow mathematics. But it makes you an idiot for trying to discuss physics.

Get over it.

What's going to happen here is I'm going to keep explaining what you claimed I can't explain in ever simpler terms until the most idiotic cretin can't help admitting it. If you want to be exposed as an idiotic cretin, it's no concern of mine. Your alternative is to lie, when the most idiotic cretin can see you're lying.

Do we really need to go there?
Da Schneib
5 / 5 (1) May 21, 2017
I can't believe I'm arguing about physics with someone who doesn't understand the origin of the inverse square law.

This is like arguing about molecular biology with someone who doesn't understand sexual reproduction.

Or like arguing about math with someone who doesn't understand 1.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
I explained that too. It's the same as the reason the intensity of light decreases by the inverse square law. The surface area of the sphere the force acts over increases as the square of the distance, and because the force is conserved, it acts with equal intensity over the surface.

Give this up, @Dingbat, you're looking stupider and stupider, or like more and more of a liar, the farther you go. There isn't anywhere to hide, there's no lie you can tell that will make it right, and it's time to admit it and move on.

Like I said, like arguing math with someone who doesn't understand 1. Or worse yet, with someone who lies about what 1 means.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
@Dingbat, gravity follows the same law as light because we live in a 3D universe and in 3D a sphere's surface area varies as the square of its radius.

It really is that simple. You'd be surprised how much physics depends on it. But maybe not since you don't appear to know any physics.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
Let's take an example: conservation of momentum. This alone is enough to tell us we live in a 3D universe; by Noether's Theorem, the symmetry of results over space implies conservation of momentum, but this is only true in the special case of 3 dimensions.

In other words, the fact I can perform an experiment in New York and the same experiment in Tokyo and get the same results implies not only that momentum is conserved but that the universe has only 3 space dimensions. This is basic physics, Physics 101. It's not a theory; it's a theorem, subject to mathematical proof.

Welcome to reality.
Da Schneib
5 / 5 (1) May 21, 2017
Why the gravity follows inverse square law like the intensity of light and not like the force from magnet?
@Dingbat, why are you falsely claiming the force from a magnetic pole doesn't follow the inverse square law? Do you have some experiment that proves this?

All that's necessary is to make a long magnet and measure the force from a nearby pole; one finds that the longer the magnet, the closer to the inverse square formula its force comes. Given the non-existence of monopoles implied by ∇⋅B = 0 this is the expected result.

You can try echoing my claims all you like, but all it does is make it obvious you're a #physicscrank.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
@Dingbat, that depends on the character of the forces. Weak force has massive bosons; this limits its range. Color force is confined; this limits its range. You're lying or ignorant. The only forces that follow the inverse square law strictly are gravity and EM.

Why are you lying? You appear to be a #physicscrank.

@Dingbat, what monopoles? Please link experimental evidence.

Why bother lying? Do you think someone won't notice? Do you only want to talk to other #physicscranks?

I'm getting tired of this; it's a waste of time talking to a #physicscrank who is either ignorant or lying. Boring.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (2) May 21, 2017
Just to review here:
1. @Dingbat #physicscrank claims I can't explain the inverse square law.
2. @Dingbat #physicscrank claims I can't show why gravity should obey the ISL.
3. @Dingbat #physicscrank claims I can't show magnetism obeys the ISL.
4. @Dingbat #physicscrank claims color and weak forces not obeying the ISL disproves the ISL.

So far every claim has been dismissed. Now, is this person lying, or a complete #physicscrank? Or both?

This is getting more and more boring. It must be Sunday morning because otherwise I wouldn't be bothering with this #physicscrank.

I already linked it
Bullsxxt. Direct lie. Link it again and prove me wrong. Or tacitly admit you lied.

Right here right now, #physicscrank.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
Direct lie, @Dingbat #physicscrank liar.

You ain't linked jack sxxt. You lie, and you are proven to lie.

Now produce the link or admit you lied and go post somewhere else where they are OK with liars.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
Sorry, @Dingbat #physicscrank liar, no linkie, you are a liar. I'm not searching, I'm not looking, I'm not letting you lie any more. Produce the link or admit you lied or be permanently labeled another #physicscrank liar who doubles down when challenged just like #TrumpLiar.

We just want to know what your character is here so we can ignore you if you're another #physicscrank liar. There's no point in discussing science with a liar; they'll say anything. And they never have a link.
Dingbone
May 21, 2017
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Da Schneib
5 / 5 (1) May 21, 2017
No linkie, you are a liar, @Dingbat #physicscrank liar.

You claim it you prove it @Dingbat #physicscrank liar. Bring the link. No link, you lie. Simple as that.

No linkie, you are a liar, @Dingbat #physicscrank liar.

You claim it you prove it @Dingbat #physicscrank liar. Bring the link. No link, you lie. Simple as that.

ProTip: don't claim you linked it when you didn't. Don't lie. You'll get caught, and it's obvious when you try to change the subject.
Da Schneib
5 / 5 (3) May 21, 2017
The amusing thing about #crank liars is they always eventually make a claim "I linked that" when they didn't. It's almost a signature; they think everyone they're talking to is stupid and won't notice they are lying.

You can just about tag them by this behavior. Personally I find it insulting that anyone would think I was paying this little attention, so I wouldn't notice, and I despise anyone who tries this trick. You should too; they're insulting your intelligence.
Da Schneib
5 / 5 (3) May 21, 2017
I think it's laziness; they already know they've been pwnt and caught lying, and they are inept at finding links on the 'Net, so they figure they'll just claim it and everyone is so stupid they won't notice.

It's the assumption that everyone else is stupid that is the signature. You can usually spot this early on when they start denying experimental evidence.
Dingbone
May 21, 2017
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Da Schneib
4 / 5 (4) May 21, 2017
BTW @Dingbat, don't be thinking I'll forget this thread or the false claims you made. I'll be pointing right back here over and over and over again whenever you lie on some later thread.

You can ask @Lenni or @RealitySchmeck about that. Enjoy.
Da Schneib
4 / 5 (4) May 21, 2017
You are a serial liar @Dingbat #physicscrank liar. You have no link, you have no evidence, you make unsubstantiated claims and dodge when challenged to provide evidence and claim nonexistent links.

There is no reason anyone should accept anything you say as having anything to do with reality and you should be ashamed of yourself.

Shame shame shame.
Dingbone
May 21, 2017
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Mimath224
4.2 / 5 (5) May 21, 2017
@Mimath, after watching @Dingbat claim I couldn't explain the inverse square law and watching me explain it, I'm surprised you're even asking about anything this idiot claims. I really do suggest you not bother with people who make claims, get them disproven, and then try to change the subject. It's really pretty probitive.

Well, I wasn't actually asking ...purely rhetorical hence my multiple '?'. I was just trying to be 'nice' about it. The reason was, that I was following you and Dingbone and I wondered why YOU were entering into such a lengthy 'conversation' this 'observer of monopoles'. I think you have wasted more time on Dingbone than I have, and I suggest that is precisely what Db wants. Have a nice day etc. (genuinely)
Da Schneib
4.2 / 5 (5) May 21, 2017
@Mimath, you're a better man than I. Guess it was late and I wasn't rational.
tomwaders
3.5 / 5 (4) May 21, 2017
Just created this account now to comment I have been a reader on phys.org for last 3-4 months . Enjoy the conversations and comments section , however weird they get sometimes. In this case @Dingbat did NOT link the article for monopoles.
Dingbone
May 21, 2017
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Seeker2
1 / 5 (1) May 21, 2017
@Seeker, you're in space so close to flat that very weak gravity doesn't have any effect, locally. It's orders of magnitude below our ability to measure locally.

So why do they define it for flat space? Why correct clocks for gravity anyway? Who needs general relativity?
Because details matter. And if you ignore GRT your GPS gives a position that's way off.
They sure do. I haven't detected any problem in measuring gravity locally.
Seeker2
1 / 5 (2) May 21, 2017
As a matter of fact earth's gravity is stronger locally than anywhere else in space, including the earth itself. As I understand clocks even run faster in Denver than they do in DC.
Da Schneib
5 / 5 (5) May 21, 2017
@Seeker, it's not at all clear to me what you're asking. If you're asking why a clock in orbit, observed by someone on the ground, runs at a different speed than a clock on the ground with them, it's because spacetime is curved differently on the ground than in orbit. Ignoring, as you say, gamma, which is also present, due to the clock in orbit traveling at orbital velocity.

If you're asking why we need relativity, it's to allow us to make those corrections so we can account for the clock in orbit, among many other such situations, running differently.

As for GPS, it's pretty much all based on clocks, so these little details can result in your GPS receiver telling you the wrong thing if we don't make these corrections.

I have no idea what you're talking about with Earth's gravity. Gravity on Jupiter (which is undeniably in space) is stronger than Earth's, so what you said doesn't seem to make much sense.
Da Schneib
5 / 5 (4) May 21, 2017
@tomwaders, there is both edification and amusement available here. One-stop shopping! ;)

You beat me to the punch on the monopole link thing; I think @Dingbat got a little confused which thread it was posting on. Of course, there were no such posted links on the monopole thread either, AFAIK, so perhaps it was a confusion with the conversations it has with the voices in its head.
RealityCheck
1 / 5 (3) May 21, 2017
@Da Schneib.

Check (and click on) @Dingbone's in-line links; as distinct from separate stand-alone links as used by most posters here. :)
Seeker2
1 / 5 (1) May 21, 2017
@DS
I have no idea what you're talking about with Earth's gravity. Gravity on Jupiter (which is undeniably in space) is stronger than Earth's, so what you said doesn't seem to make much sense.
I'm not talking about Jupiter's gravity. I'm talking about earth's gravity. 1g is the strongest gravity exerted by earth than anywhere else in the U including Jupiter. Earth's gravity is even smaller at the supermassive black hole at the center of our galaxy.
Seeker2
1 / 5 (1) May 21, 2017
@DS
@Seeker, it's not at all clear to me what you're asking.
You told us the cesium transition frequency for flat spacetime. I'm asking what is it at 1g.
tomwaders
3.7 / 5 (3) May 21, 2017
"Check (and click on) @Dingbone's in-line links" Ok. Now I see the link. Oddly there is no visual indication to infer it has a hyperlink to it which usually is differentiated by color, underline etc. And that's a site issue. Or maybe it does not show correctly on Safari.
Whydening Gyre
5 / 5 (4) May 21, 2017
LOL... Check the sentence "But we observed the monopoles" at this page.

Technically, they did not.
They observed "quantum" monopoles decaying into magnetic monopole "analogues"...
From that article;
"Scientists at Amherst College (USA) and Aalto University (Finland) have made the first experimental observations of the {dynamics} of isolated monopoles in quantum matter."

Whydening Gyre
5 / 5 (2) May 21, 2017
"Check (and click on) @Dingbone's in-line links" Ok. Now I see the link. Oddly there is no visual indication to infer it has a hyperlink to it which usually is differentiated by color, underline etc. And that's a site issue. Or maybe it does not show correctly on Safari.

I use Google and it show only a slight color difference. it also underlines, but only when you hover over it.
Whydening Gyre
5 / 5 (3) May 21, 2017
@DS
@Seeker, it's not at all clear to me what you're asking.
You told us the cesium transition frequency for flat spacetime. I'm asking what is it at 1g.

Never did get the "flat space/time" thing...
It's always curving somewhere...
As to your question - 1g is a measurement parameter of (local) space/time. (which also happens to correspond with curvature of space/time - go figure)
The cesium transition frequency should always read the same in whatever locality it is a part of - TO the local observer. The difference appears when it it has spent any time in - a different locality.
TheGhostofOtto1923
3 / 5 (4) May 21, 2017
I strongly recommend you do not demonstrate your ignorance further but instead remain quiet and see if you can learn some real physics
You do know dingbat is zephyr don't you? And you're really trying to reason with him?

Just report him until he's banned again. Hey alizee how many times has it been? Thirty maybe?

This is wg's fault.
Da Schneib
5 / 5 (2) May 21, 2017
@DS
I have no idea what you're talking about with Earth's gravity. Gravity on Jupiter (which is undeniably in space) is stronger than Earth's, so what you said doesn't seem to make much sense.
I'm not talking about Jupiter's gravity. I'm talking about earth's gravity. 1g is the strongest gravity exerted by earth than anywhere else in the U including Jupiter. Earth's gravity is even smaller at the supermassive black hole at the center of our galaxy.
I don't know what "Earth's gravity" means.

The gravity field is omnipresent throughout space. At various points in space it is influenced to various values by matter that is present near those points; but the gravity field itself isn't "exerted" by anything. It's not possible to distinguish "Earth's gravity field" from "the Sun's gravity field" somehow.
[contd]
Da Schneib
5 / 5 (2) May 21, 2017
[contd]
It's a calculational convenience to say that the gravity field on Earth's surface is such-and-such, due to its mass, but in fact, Jupiter, the Sun, and the Moon all influence the value of the curvature of space time on the Earth's surface all the time too, though with much less influence than the Earth's at that point.

In fact, this is true of all fields. There isn't some sort of way to determine where the value of the field "came from." We often use the calculational convenience to say "this much of the field came from this, and that much from over there" but the fact is, the field is what it is.

Does that help clear things up for you?
Da Schneib
5 / 5 (2) May 21, 2017
@DS
@Seeker, it's not at all clear to me what you're asking.
You told us the cesium transition frequency for flat spacetime. I'm asking what is it at 1g.
The same. Measurement of the frequency is done locally by the atomic clock, so gravity is not strong enough to alter it measurably. The real question is where you are when you're watching it. If you are also local to it (it's "in your lab") then that's what you'll see too. If it's on the ground and you're in orbit observing it, then you'll see something different, and vice versa. GRT gives the equations for what you can expect to see if you're not observing it locally, and for what its value will be if someone takes it "out of your lab" and flies around the world with it, or boosts it to orbit and then brings it back, compared to an identical clock that was synchronized with it that remains "in your lab."

Perspective and history are important here.
Da Schneib
5 / 5 (2) May 21, 2017
Let's try this another way: you yourself are under the influence of the gravity field wherever you are. You will always perceive a clock that is under the influence of the same value of the gravity field as you are to keep time to one second per second, or have 9,192,631,770 cycles during what you define as 1 second if it is a cesium atomic clock. You will also perceive some clock in a different gravity field as having some different number of cycles, depending on the difference between your field and the field where that clock is. A clock under the influence of the same gravity field value you are is equivalent to a local clock, as long as it's not moving relative to you.
Da Schneib
3.7 / 5 (3) May 21, 2017
@tomwaders, I missed it too. As you say that's a site issue.

As I posted in that article, the so-called "monopoles" are not actual magnetic monopoles. They are phenomena which, when viewed from a certain angle, have what appears to be the same field configuration as a monopole; but viewed from other angles, do not.

@Dingbat remains a #physicscrank; I can't state whether it's a liar or not, because I can't tell whether it is merely foolish enough not to understand the article, or deliberately falsifying it.
Da Schneib
5 / 5 (2) May 21, 2017
@DS
@Seeker, it's not at all clear to me what you're asking.
You told us the cesium transition frequency for flat spacetime. I'm asking what is it at 1g.

Never did get the "flat space/time" thing...
It's always curving somewhere...
It means the local value of gravity is zero. This happens far outside galaxy clusters, and at particular points within the Solar System at particular times depending on the exact positions of the planets.

As to your question - 1g is a measurement parameter of (local) space/time. (which also happens to correspond with curvature of space/time - go figure)
The cesium transition frequency should always read the same in whatever locality it is a part of - TO the local observer. The difference appears when it it has spent any time in - a different locality.
Or is in such a locality now. You have it precisely, @Whyde.
Da Schneib
5 / 5 (3) May 21, 2017
Circling back around to the original point of the article, I'm still reviewing the paper, but it still looks pretty good to me. I'm not competent to evaluate all the math, but the basic idea looks correct so far.

And I still think this is a peek at the math that will be required for any quantum theory of gravity.
Seeker2
1 / 5 (1) May 21, 2017
@WG
The cesium transition frequency should always read the same in whatever locality it is a part of - TO the local observer. The difference appears when it it has spent any time in - a different locality.
Moving the clock to a different location is pointless. Use similar clocks in say Denver and DC. Track their cumulative time. Track them long enough and you will find they start to diverge. Think there is a problem with the clocks? Could be. So switch them and repeat the measurements. Same effect? Then there's nothing wrong with the clocks.
Da Schneib
5 / 5 (2) May 21, 2017
@Seeker, are Denver and DC both "in the lab?" Given Denver is a mile high, I think not. But I bet our equipment isn't good enough to show the difference.
Seeker2
1 / 5 (1) May 21, 2017
Let's try this another way: you yourself are under the influence of the gravity field wherever you are. You will always perceive a clock that is under the influence of the same value of the gravity field as you are to keep time to one second per second, or have 9,192,631,770 cycles during what you define as 1 second if it is a cesium atomic clock. You will also perceive some clock in a different gravity field as having some different number of cycles, depending on the difference between your field and the field where that clock is. A clock under the influence of the same gravity field value you are is equivalent to a local clock, as long as it's not moving relative to you.
You don't define the second from the cycles on your clock unless you're in free fall. Of course you could know the expected difference from your locality and free fall and define the second from your local observation if you do the correction properly.
Seeker2
1 / 5 (1) May 21, 2017
@Seeker, are Denver and DC both "in the lab?" Given Denver is a mile high, I think not. But I bet our equipment isn't good enough to show the difference.
Yes there is a lab in Denver and I suppose one in DC. Run those clocks long enough and I assure you you will find they diverge. Else pitch GR. But you say there must be something wrong with the clocks? No problem. Switch the clocks and repeat the measurement.
Da Schneib
5 / 5 (2) May 21, 2017
You don't define the second from the cycles on your clock unless you're in free fall.
No, that's incorrect. If your clock is local then you always define seconds from your clock.

Yes there is a lab in Denver and I suppose one in DC.
No, that's not what I said. I said "are they the same lab as you define it." And you just answered, "No." So that's fine, the DC lab is local to DC and the Denver lab is local to Denver.

I assure you you will find they diverge.
Eventually, yes, they must. They are not local to one another.

An important question here is what you choose to define as local.
Seeker2
1 / 5 (1) May 21, 2017
And I still think this is a peek at the math that will be required for any quantum theory of gravity.
Does the expansion of spacetime require a quantum theory? If not then forget about any quantum theory of gravity.
Seeker2
1 / 5 (1) May 21, 2017
You don't define the second from the cycles on your clock unless you're in free fall.
No, that's incorrect. If your clock is local then you always define seconds from your clock.
Define night as day if you want. But it won't do you that much good because that's not how it's done.
Da Schneib
5 / 5 (2) May 21, 2017
I don't understand what you're asking, @Seeker. The expansion of spacetime is an observation; it doesn't require any theory at all. It's a fact.

The theory is a description of how it happens. We have telescopes and can look and see what it does; the theory is the description of what we see in the telescopes.

Why it happens is currently in the realm of conjecture or even speculation.

that's not how it's done
I can't imagine how you think it's done if it's not from local atomic clocks. How about you explain that to me.

I have to tell you I am an amateur astronomer and I keep time in my house that is good to 10^-6 seconds. It's important enough to be worth the effort. And I don't need an atomic clock.
Seeker2
1 / 5 (1) May 21, 2017
@DS
that's not how it's done
I can't imagine how you think it's done if it's not from local atomic clocks. How about you explain that to me.
I did once but I guess you weren't paying attention. You have to know enough about GR to apply the right correction for altitude to your local time.
Da Schneib
5 / 5 (2) May 21, 2017
You have to know enough about GR to apply the right correction for altitude to your local time.
So? Explain it. Then you'll know how it works for orbits.
Seeker2
1 / 5 (1) May 21, 2017
@DS
I don't understand what you're asking, @Seeker. The expansion of spacetime is an observation; it doesn't require any theory at all. It's a fact.
So I think you answered that question. Ergo gravity doesn't require any quantum theory. It just happens as a result of expansion. I know it's counter-intuitive, but that's just the way things work sometimes.
Da Schneib
5 / 5 (2) May 21, 2017
It just happens as a result of expansion.
You mean gravity? No, that's incorrect. Gravity would happen as a result of mass whether expansion was occurring or not.
Seeker2
1 / 5 (1) May 21, 2017
You have to know enough about GR to apply the right correction for altitude to your local time.
So? Explain it. Then you'll know how it works for orbits.
I think clocks in orbit are in free fall.
Da Schneib
5 / 5 (2) May 21, 2017
I think clocks in orbit are in free fall.
That's only approximately true, and doesn't matter to the curvature of the space they're in.
Seeker2
1 / 5 (1) May 21, 2017
It just happens as a result of expansion.
You mean gravity? No, that's incorrect. Gravity would happen as a result of mass whether expansion was occurring or not.
I told you it was counter-intuitive. Gravity happens as a result of quantized mass which doesn't expand while everything else around it is.
Seeker2
1 / 5 (1) May 21, 2017
I think clocks in orbit are in free fall.
That's only approximately true, and doesn't matter to the curvature of the space they're in.
Changes in g-values are compensated by changes in the orbit. Approximate truth is above my pay grade.
Seeker2
1 / 5 (1) May 21, 2017
...I don't need an atomic clock.
So you need resolution, not accuracy. I understand.
Da Schneib
5 / 5 (1) May 22, 2017
@Seeker, just because you're in free fall doesn't mean you're in flat space.

As for timekeeping, no, I need accuracy. Astronomy requires good timekeeping so you can see things like Jupiter's moons disappearing behind it and reappearing on the other side, and so you can point the telescope.
Seeker2
1 / 5 (1) May 22, 2017
@Seeker, just because you're in free fall doesn't mean you're in flat space.
Good point. Where would you fall?
As for timekeeping, no, I need accuracy. Astronomy requires good timekeeping so you can see things like Jupiter's moons disappearing behind it and reappearing on the other side, and so you can point the telescope.
Sounds like about one second accuracy should do.
antialias_physorg
5 / 5 (2) May 22, 2017
Where would you fall?

Along a geodesic. Which can be towards a massive body like Earth - but if your lateral motion is great enough it can be around the Earth as well (notice how rockets always curve when they go up? It's because they need to get *lateral* speed rather than height to get their stuff in orbit - and stay there)

Instead of typing it out this guy gives a pretty good answer
https://physics.s...e-no-for
Seeker2
1 / 5 (1) May 22, 2017
Where would you fall?
Along a geodesic. Which can be towards a massive body like Earth -
There is no flat spacetime in earth's gravitational field. Add a second body, such as the moon, and there is no gravity at the Lagrange points. But normally you wouldn't describe a point as flat.
antialias_physorg
5 / 5 (3) May 22, 2017
Where would you fall? .

Wherever the geodesic ends. Or if your geodesic just curves onto itself you'll just keep going "round and round". Note that the word 'curve' is to be taken with a grain of salt. It only seems to curve if you want to impose a euclidean view on space. From a spacetime point of view stuff (like Earth, or the sun or the ISS) moves in straight lines.

Humans (unfortunately) do tend to think in terms of euclidian space. It's a useful approximation to the circumstances that were relevant during our evolution. But space isn't euclidian. There's a reason why it's called spacetime and not "space and time"
Seeker2
1 / 5 (1) May 22, 2017
Where would you fall? .
Wherever the geodesic ends.
And where would that be, in flat spacetime?
antialias_physorg
5 / 5 (2) May 22, 2017
In flat spacetime (as in curved spacetime) the geodesic is a straight line. That's what the definition of a geodesic is. (Note that the universal ruler for spacetime is light, because the speed of light is the only thing that doesn't change under transformation from one frame of reference to another)

If spacetime were universally flat then what you would call a straight line in euclidian space and what is a geodesic in spacetime would be identical.
Seeker2
1 / 5 (1) May 22, 2017
In flat spacetime (as in curved spacetime) the geodesic is a straight line.
So in flat spacetime you would fall on a straight line. I can believe that provided you got a little nudge to start the fall.
Seeker2
1 / 5 (1) May 22, 2017
cont
In curved spacetime, however, you don't need a nudge. That's why they call it free fall. Curved spacetime, however, is only approximately true, because you could fall straight down. No curve required.
rossim22
1 / 5 (1) May 22, 2017
Maybe a reinvestigation of redshift is necessary before inventing new physics.
Da Schneib
5 / 5 (2) May 22, 2017
@Seeker, curved spacetime doesn't work like curved space would. Remember that to all light, it's not curved. Same for gravity. What physicists call a curve is a straight line as we see it. Laser beams move in straight lines. They're called geodesics.
Da Schneib
5 / 5 (2) May 22, 2017
To get really radical, let's go near a black hole with a tetrahedron of satellites connected by laser beams around us.

To us, as we fall toward the event horizon, the tetrahedron remains a tetrahedron, as long as the satellites are close enough, and "close enough" gets closer and closer the further in we go.

To someone far away watching, the tetrahedron gets more and more distorted, and the laser beams look more and more curved.

It's just as important where you're watching from as where what you're watching is. This is a key concept.
Seeker2
not rated yet May 23, 2017
@Seeker, curved spacetime doesn't work like curved space would.
Neither one works. Maybe warped but not curved. Especially like around a black hole.
Da Schneib
5 / 5 (2) May 23, 2017
That's just semantic games. Call it warped, call it curved, call it bent or folded, it all comes out to the same thing. Otherwise there wouldn't be such things as orbits.
Seeker2
not rated yet May 23, 2017
You wish. Call it symmetry. Call it conservation of energy. Or momentum. Call it Noether's theorem. Words matter in physics.
Seeker2
not rated yet May 23, 2017
cont
Well I guess you could say stretching is curving. But I just don't see it that way.
Seeker2
not rated yet May 23, 2017
cont
For example gravity pulls down on a rope suspended between its two ends. The rope is curved but spacetime is stretched.
Seeker2
not rated yet May 23, 2017
spacetime is stretched.
. That is, gravity pulls down on the rope. Or stretches the rope downward.
Seeker2
not rated yet May 23, 2017
cont
sort of like confusion between cause and effect.
Da Schneib
5 / 5 (1) May 23, 2017
@Seeker, orbits are curved. It's kind of obvious. I don't see much room for confusion.

Just sayin'.
xinhangshen
1 / 5 (1) May 23, 2017
Da Schneib, I can clearly tell you that the corrections of the clocks on the GPS satellites are based on the synchronization (one criterion only), not by GR + SR. It is just the misinterpretation by relativists that the corrections are calculated by GRT + SRT.
Seeker2
not rated yet May 23, 2017
@Seeker, orbits are curved. It's kind of obvious. I don't see much room for confusion.

Just sayin'.
Good thing too. Just don't try selling me that snake oil about objects in orbit traveling in straight lines in curved spacetime, thank you.
Whydening Gyre
not rated yet May 24, 2017
@Seeker, orbits are curved. It's kind of obvious. I don't see much room for confusion.

Just sayin'.
Good thing too. Just don't try selling me that snake oil about objects in orbit traveling in straight lines in curved spacetime, thank you.

Orbits, are a combo of gravity and kinetics. Constantly recalculated (re-added), every single moment of Planck time(or even less). They are travelling a combined 2 straight vectors (possibly 3 or even more) WITHIN space/time. Curvature of space/time is irrelevant (other than that it trickle-down determines subordinate curvatures....) If it ISN'T curved, why would anything inside of it curve?
Seeker2
not rated yet May 24, 2017
@WG
Curvature of space/time is irrelevant (other than that it trickle-down determines subordinate curvatures....) If it ISN'T curved, why would anything inside of it curve?
Because of gravity.
Seeker2
not rated yet May 24, 2017
Note there are 2 effects of the expansion of spacetime on photons. There is expansion as a function of time. This leads to redshift. But expansion as a function of position leads to gravity. That is space is expanding faster over your head than under your feet because matter displaces spacetime under your feet. This gradient will then divert passing photons towards matter - regions of less expansion. So in a way redshift and gravity are the two different effects of the two different modes of spacetime expansion.
Whydening Gyre
not rated yet May 25, 2017
@WG
Curvature of space/time is irrelevant (other than that it trickle-down determines subordinate curvatures....) If it ISN'T curved, why would anything inside of it curve?
Because of gravity.

So.... You're saying gravity determines space/time characteristics?
Seeker2
not rated yet May 25, 2017
So.... You're saying gravity determines space/time characteristics?
NO WAY!
xinhangshen
1 / 5 (1) May 25, 2017
@xinhangshen
I have no idea what your on about...
"Einstein's general relativity theory says that gravity curves space and time, resulting in a tendency for the orbiting clocks to tick slightly faster, by about 45 microseconds per day. The net result is that time on a GPS satellite clock advances faster than a clock on the ground by about 38 microseconds per day."
http://physicscen...will.cfm

For this reason the satellites clocks are designed to run "slow", because of empirical observation.
Ground control stations also monitor and update a satellites time as well as other navigational data, at least once a day.


It seems that you don't have any idea about kinematic time dilation which is observer dependent, very different from the gravitational time dilation, and can't be corrected in the same way. It is this time dilation that does exist in the corrections of the atomic clocks on the GPS satellites. Please review special relativity again.
Whydening Gyre
5 / 5 (1) May 26, 2017


@WG
Curvature of space/time is irrelevant (other than that it trickle-down determines subordinate curvatures....) If it ISN'T curved, why would anything inside of it curve?
Because of gravity.

So.... You're saying gravity determines space/time characteristics?
NO WAY!

Seems like that is what your saying.
Only other option is that Space/Time creates curvature. Which it can only do by being - curved.
Seeker2
not rated yet May 26, 2017
...Space/Time creates curvature. Which it can only do by being - curved.
Bowl sheet. It creates curvature by pulling down. Like my rope example. It's not rocket science. Really.
Whydening Gyre
not rated yet May 26, 2017
...Space/Time creates curvature. Which it can only do by being - curved.
Bowl sheet. It creates curvature by pulling down. Like my rope example. It's not rocket science. Really.

You are saying a vector direction, then...
Seeker2
not rated yet May 26, 2017
You are saying a vector direction, then...
A total force vector having both direction and magnitude.
Whydening Gyre
5 / 5 (1) May 26, 2017
You are saying a vector direction, then...
A total force vector having both direction and magnitude.

I see...
And gravity is generating that force, right? A property of mass...
Question... is everything within our visible U in motion? Straight or curved? (or cork-screwing...)
To me, the cork-screwing appears to be a result of gravity affecting massive bodies from a number of different vectors...
Seeker2
not rated yet May 27, 2017
...gravity is generating that force, right?
I don't think so.
A property of mass...
Like people are a property of the weather.
Question... is everything within our visible U in motion? Straight or curved? (or cork-screwing...)
We wouldn't know if it was because everything is uncertain as far as position and time is concerned.
To me, the cork-screwing appears to be a result of gravity affecting massive bodies from a number of different vectors...
Cound be a way of conserving energy and momentum.
Whydening Gyre
5 / 5 (1) May 27, 2017
...gravity is generating that force, right?
I don't think so.

Kinetic, then?
A property of mass...
Like people are a property of the weather.

In a roundbout way - there are..:-)
Question... is everything within our visible U in motion? Straight or curved? (or cork-screwing...)
We wouldn't know if it was because everything is uncertain as far as position and time is concerned.

I disagree. We know where we ARE. And what our motion(s) are.
To me, the cork-screwing appears to be a result of gravity affecting massive bodies from a number of different vectors...
Could be a way of conserving energy and momentum.

The U does like to take the path of least resistance...:-)
Seeker2
not rated yet May 27, 2017
...gravity is generating that force, right?
I don't think so.
Kinetic, then?
The gravitational force is generated by gradients in the dark energy.
A property of mass...
Like people are a property of the weather.
In a roundbout way - there are..:-)
Ok. let's call it complicit. Quantized matter is complicit in about 25% of gravity. The rest is dark matter.
Question... is everything within our visible U in motion? Straight or curved? (or cork-screwing...)
We wouldn't know if it was because everything is uncertain as far as position and time is concerned.
I disagree. We know where we ARE. And what our motion(s) are.
Maybe but the question was everything not we.
To me, the cork-screwing appears to be a result of gravity affecting massive bodies from a number of different vectors...
Could be a way of conserving energy and momentum.
The U does like to take the path of least resistance...:-)
Sounds right on.

Seeker2
not rated yet May 27, 2017
The U does like to take the path of least resistance...:-)
Sounds right on.
Something called the principle of least action comes to mind. It's been a while though.
Da Schneib
5 / 5 (2) Jun 01, 2017
Physicist Sabine Hossenfelder has weighed in on the paper this article is about, after she corresponded with the authors. She thinks there are some problems with it, but has respect for the math they did. You can read her thoughts on her blog, the pretty well known Backreaction: http://backreacti...lve.html
Seeker2
not rated yet Jun 02, 2017
For what it's worth - on first read it sounds like they're trying to derive exponential expansion from vacuum fluctuations and GR. As we all know I think gravity is a result of exponential expansion. I have to believe GR effectively describes gravity mathematically but trying to use it to derive exponential expansion just confuses cause and effect. Working on it but if I come onto anything about curved spacetime I really will be beating the drums. :-)
Seeker2
not rated yet Jun 02, 2017
Note associating vacuum fluctuations with the cosmological constant and exponential expansion would really be neat but using gravity in making the association would seem to be confusing cause and effect again.
Seeker2
not rated yet Jun 02, 2017
Note associating vacuum fluctuations with the cosmological constant and exponential expansion would really be neat but using gravity in making the association would seem to be confusing cause and effect again.
Seeker2
not rated yet Jun 02, 2017
An interesting possibility would be if you could relate a vacuum fluctuation with the uncertainty principle. Then from the vacuum fluctuation to the expansion of spacetime and this expansion to gravity, giving us a quantum theory of gravity, perhaps? I like, anyways.
Mimath224
5 / 5 (1) Jun 02, 2017
@Da Schneib Glad you pointed that out Sabine Hossenfelder's opinion...don't know about these websites. I'm still reading but got confused along the way and what S.H. says might be the reason;
'They are using classical gravity coupled to the expectation values of the quantum field theory, a mixture known as 'semi-classical gravity' in which gravity is not quantized.'
As a layman I'm uncertain about knowledge of these deep papers (well, deep to me anyway) but I do recall reading somewhere that 'quadratic coupling' is also expected in/with the S-E tensor. I then wondered if this was in the paper...it doesn't seem to be. Of course, that might simply mean that it is but not as I would recognize it or accounted for elsewhere and I haven't the knowledge to see it. Da Schneib, you really are well informed and knowledgeable
Great stuff...I like it.

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