MACHOs are dead. WIMPs are a no-show. Say hello to SIMPs: New candidate for dark matter

December 4, 2017 by Robert Sanders
Conventional WIMP theories predict that dark matter particles rarely interact with one another, and only weakly with normal matter. Hitoshi Murayama of UC Berkeley and Yonit Hochberg of Hebrew University predict that dark matter SIMPs, comprised of a quark and an antiquark, would collide and interact strongly with one another, producing noticeable effects when the dark matter in galaxies collide. Credit: Kavli IPMU graphic

The intensive, worldwide search for dark matter, the missing mass in the universe, has so far failed to find an abundance of dark, massive stars or scads of strange new weakly interacting particles, but a new candidate is slowly gaining followers and observational support.

Called SIMPs - strongly interacting massive particles - they were proposed three years ago by University of California, Berkeley theoretical physicist Hitoshi Murayama, a professor of physics and director of the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU) in Japan, and former UC Berkeley postdoc Yonit Hochberg, now at Hebrew University in Israel.

Murayama says that recent observations of a nearby galactic pile-up could be evidence for the existence of SIMPs, and he anticipates that future particle physics experiments will discover one of them.

Murayama discussed his latest theoretical ideas about SIMPs and how the colliding support the theory in an invited talk Dec. 4 at the 29th Texas Symposium on Relativistic Astrophysics in Cape Town, South Africa.

Astronomers have calculated that dark matter, while invisible, makes up about 85 percent of the mass of the universe. The solidest evidence for its existence is the motion of stars inside galaxies: Without an unseen blob of dark matter, galaxies would fly apart. In some galaxies, the visible stars are so rare that dark matter makes up 99.9 percent of the mass of the galaxy.

Theorists first thought that this invisible matter was just normal matter too dim to see: failed stars called brown dwarfs, burned-out stars or . Yet so-called massive compact halo objects - MACHOs - eluded discovery, and earlier this year a survey of the Andromeda galaxy by the Subaru Telescope basically ruled out any significant undiscovered population of black holes. The researchers searched for black holes left over from the very early universe, so-called primordial black holes, by looking for sudden brightenings produced when they pass in front of background stars and act like a weak lens. They found exactly one - too few to contribute significantly to the mass of the galaxy.

MACHOs are dead, WIMPs are a no-show -- say hello to SIMPs
The fundamental structure of the proposed SIMP (strongly interacting massive particle) is similar to that of a pion (left). Pions are composed of an up quark and a down antiquark, with a gluon (g) holding them together. A SIMP would be composed of a quark and an antiquark held together by a gluon (G). Credit: Kavli IPMU graphic

"That study pretty much eliminated the possibility of MACHOs; I would say it is pretty much gone," Murayama said.

WIMPs—weakly interacting massive particles—have fared no better, despite being the focus of researchers' attention for several decades. They should be relatively large - about 100 times heavier than the proton - and interact so rarely with one another that they are termed "weakly" interacting. They were thought to interact more frequently with normal matter through gravity, helping to attract normal matter into clumps that grow into galaxies and eventually spawn stars.

SIMPs interact with themselves, but not others

SIMPs, like WIMPs and MACHOs, theoretically would have been produced in large quantities early in the history of the universe and since have cooled to the average cosmic temperature. But unlike WIMPs, SIMPs are theorized to interact strongly with themselves via gravity but very weakly with normal matter. One possibility proposed by Murayama is that a SIMP is a new combination of quarks, which are the fundamental components of particles like the proton and neutron, called baryons. Whereas protons and neutrons are composed of three quarks, a SIMP would be more like a pion in containing only two: a quark and an antiquark.

The SIMP would be smaller than a WIMP, with a size or cross section like that of an atomic nucleus, which implies there are more of them than there would be WIMPs. Larger numbers would mean that, despite their weak interaction with normal matter - primarily by scattering off of it, as opposed to merging with or decaying into normal matter - they would still leave a fingerprint on normal matter, Murayama said.

He sees such a fingerprint in four colliding galaxies within the Abell 3827 cluster, where, surprisingly, the dark matter appears to lag behind the . This could be explained, he said, by interactions between the dark matter in each galaxy that slows down the merger of dark matter but not that of normal matter, basically stars.

MACHOs are dead, WIMPs are a no-show—say hello to SIMPs
Conventional WIMP theories predict a highly peaked distribution, or cusp, of dark matter in a small area in the center of every galaxy. SIMP theory predicts a spread of dark matter in the center, which is more typical of dwarf galaxies. Credit: Kavli IPMU graphic based on NASA, STScI images

"One way to understand why the dark matter is lagging behind the luminous matter is that the actually have finite size, they scatter against each other, so when they want to move toward the rest of the system they get pushed back," Murayama said. "This would explain the observation. That is the kind of thing predicted by my theory of dark matter being a bound state of new kind of quarks."

SIMPs also overcome a major failing of WIMP theory: the ability to explain the distribution of dark matter in small galaxies.

"There has been this longstanding puzzle: If you look at dwarf galaxies, which are very small with rather few stars, they are really dominated by dark matter. And if you go through numerical simulations of how dark matter clumps together, they always predict that there is a huge concentration towards the center. A cusp," Murayama said. "But observations seem to suggest that concentration is flatter: a core instead of a cusp. The core/cusp problem has been considered one of the major issues with dark matter that doesn't interact other than by gravity. But if dark matter has a finite size, like a SIMP, the particles can go 'clink' and disperse themselves, and that would actually flatten out the mass profile toward the center. That is another piece of 'evidence' for this kind of theoretical idea."

Ongoing searches for WIMPs and axions

Ground-based experiments to look for SIMPs are being planned, mostly at accelerators like the Large Hadron Collider at CERN in Geneva, where physicists are always looking for unknown particles that fit new predictions. Another experiment at the planned International Linear Collider in Japan could also be used to look for SIMPs.

As Murayama and his colleagues refine the theory of SIMPs and look for ways to find them, the search for WIMPs continues. The Large Underground Xenon (LUX) dark matter experiment in an underground mine in South Dakota has set stringent limits on what a WIMP can look like, and an upgraded experiment called LZ will push those limits further. Daniel McKinsey, a UC Berkeley professor of physics, is one of the co-spokespersons for this experiment, working closely with Lawrence Berkeley National Laboratory, where Murayama is a faculty senior scientist.

This Hubble Space Telescope image of the galaxy cluster Abell 3827 shows the ongoing collision of four bright galaxies and one faint central galaxy, as well as foreground stars in our Milky Way galaxy and galaxies behind the cluster (Arc B and Lensed image A) that are distorted because of normal and dark matter within the cluster. SIMPs could explain why the dark matter, unseen but detectable because of the lensing, lags behind the normal matter in the collision. Credit: University of California - Berkeley

Physicists are also seeking other that are not WIMPs. UC Berkeley faculty are involved in two experiments looking for a hypothetical particle called an axion, which may fit the requirements for . The Cosmic Axion Spin-Precession Experiment (CASPEr), led by Dmitry Budker, a professor emeritus of physics who is now at the University of Mainz in Germany, and theoretician Surjeet Rajendran, a UC Berkeley professor of physics, is planning to look for perturbations in nuclear spin caused by an axion field. Karl van Bibber, a professor of nuclear engineering, plays a key role in the Axion Dark Matter eXperiment - High Frequency (ADMX-HF), which seeks to detect axions inside a microwave cavity within a strong magnetic field as they convert to photons.

"Of course we shouldn't abandon looking for WIMPs," Murayama said, "but the experimental limits are getting really, really important. Once you get to the level of measurement, where we will be in the near future, even neutrinos end up being the background to the experiment, which is unimaginable."

Neutrinos interact so rarely with normal that an estimated 100 trillion fly through our bodies every second without our noticing, something that makes them extremely difficult to detect.

"The community consensus is kind of, we don't know how far we need to go, but at least we need to get down to this level," he added. "But because there are definitely no signs of WIMPs appearing, people are starting to think more broadly these days. Let's stop and think about it again."

Explore further: Video: Dark matter hunt with LUX-ZEPLIN

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Merrit
3 / 5 (8) Dec 04, 2017
Or maybe they should look at their model. Our current model is basically saying it is incorrect or incomplete by proof by contradiction. DM and energy is the contradiction. The hard part is determining the issue, the part of the model assumed to be correct. While the issue manifested itself as a descrempancy between predicted rotation curves and actual rotation curves, by no means does that mean the issue has to do with gravity. The issue could well be deeper than that. For instance, we could be wrong about the distances, mass, time, and or not applied GR correctly. Really what needs to be done is a thorough examination of the model itself for any assumptions that could be off. (Cosmology makes a lot of assumptions )
Hyperfuzzy
2.6 / 5 (5) Dec 04, 2017
Just stop the bull$hit!
mackita
2 / 5 (10) Dec 04, 2017
MACHOs are dead. WIMPs are a no-show. Say hello to SIMPs
This is just the gradualist iterative approach. First of all, the scientists want to save general relativity, because dark matter generates lensing without no apparent matter. So that they're inventing particles which would be heavy but unobservable enough for to explain the above controversy. MACHO's are heavy (up to 0.3 lunar masses), WIMPs are less heavier (up to mass of lead atom), SIMPs even less (up to mass of proton). Axions with extreme low mass (fraction of single eV) were also excluded.

Apparently there is still lotta wiggling space where to go. The physicists could indeed advance with their research faster, but why the hell they should do it, until the money are going? They would be an idiots - and the scientists are smart people in general.
mackita
2.2 / 5 (10) Dec 04, 2017
The core/cusp problem has been considered one of the major issues with dark matter that doesn't interact other than by gravity
Many these problems could be removed if we would consider the dark matter a charged system of normal particles, like plasma. I presume portion of it may be formed by positrons, because their annihilation gamma signal we can really observe not just at the center of galaxy, but also around Earth. But the naked atom nuclei stripped of most electrons would work in the same way - they would repel itself at distance, thus prohibiting their collapsing. Because they have no electrons to excite, they're also not absorbing and less or more dark for visible spectrum.

Why to invent new particles, when we have simplest answers untested yet? I see, it could be part of occupation problem of contemporary physics, which generates jobs for itself.
andyf
5 / 5 (8) Dec 04, 2017
And there I was wondering how long it would take for someone to say 'plasma'

Wooo!
Parsec
3 / 5 (3) Dec 04, 2017
And there I was wondering how long it would take for someone to say 'plasma'

Wooo!


In effect, the proposal that DM particles are SIMP's that strongly interact with each other makes them act far more like a plasma than WIMP's. By postulating strong self interactions, we can get all sorts of fun nonlinear behavior.

One problem I see however is that any candidate particle must be stable in the sense it cannot decay. And we know about all of the stable particles made from all of the quark types we know of. New quark types, particularly new stable quark types, are strongly contraindicated by what we currently know.
mackita
1 / 5 (4) Dec 04, 2017
are SIMP's that strongly interact with each other makes them act far more like a plasma than WIMP'
Unfortunately for plasma universe supporters, the physicists have STRONG nuclear interaction on mind with SIMPs, not electromagnetic one. This interaction applies to very short distances only. But frankly I don't understand, when they're talking about hypothetical SIMPs particles which are held together by gluons, why they're not talking just about protons and atom nuclei, which are the most trivial examples of such a particles... ;-) The looking for shadow under candlestick is very common attitude of contemporary theoretical physics.
mackita
1 / 5 (4) Dec 04, 2017
Once you get to the level of measurement, where we will be in the near future, even neutrinos end up being the background to the experiment, which is unimaginable
The neutrinos may represent way higher fraction of dark matter, than it's assumed by now. Why to look for WIMPs and ignore the neutrinos at the same moment? We already have some indicia for it. For example we know, that some neutrinos catalyze the radioactive decays. And the speed of radioactive decays of some elements depends on distance from Sun in rather observable way - therefore there may exist a density gradient of neutrinos. The average speed of neutrinos which are in thermal equilibrium with CMBR corresponds just the escape velocity from Sun - therefore the Sun would keep a gradient of neutrinos around itself simply by its gravity.
Shabs42
5 / 5 (8) Dec 04, 2017
The physicists could indeed advance with their research faster, but why the hell they should do it, until the money are going? They would be an idiots - and the scientists are smart people in general.


Right, who wants a Nobel Prize when you could drag out your research and receive a much lower salary than you could get by working in the private sector?
cantdrive85
1.8 / 5 (5) Dec 04, 2017
Wimps, Simps, and pions, sounds like a conference of astrophysicists and their "black and dark" acolytes.
howhot3
5 / 5 (5) Dec 04, 2017
SIMP is a new combination of quarks,

I'm just not getting it. At what energy do they exist and what type quarks? This would have to be very very common that it should have been seen in a collider already, unless the quarks are very top end of the energy scale and the pair would need to be extremely stable. That seems to be a far fetchem to me.
mackita
1 / 5 (5) Dec 04, 2017
Right, who wants a Nobel Prize when you could drag out your research and receive a much lower salary than you could get by working in the private sector?
There are two strategies of personal carrier aspiration - we could label them k- and r-strategies in analogy with biological reproductive strategies. You can work on foreign projects, follow order of your superior in private sector and to get lotta money for it, so you can realize yourself in your free time as a hobby. Or you can work on your own projects all the time, of course for lower salary of public sector - but with higher degree of personal freedom.
mackita
1.7 / 5 (6) Dec 04, 2017
I'm just not getting it. At what energy do they exist and what type quarks? This would have to be very very common that it should have been seen in a collider already, unless the quarks are very top end of the energy scale and the pair would need to be extremely stable. That seems to be a far fetched to me.
As I explained above in first post, it's completely fresh ad-hoced model motivated only by preservation of WIMPs searching strategy under the situation when mass spectrum for WIMPs has been nearly completely excluded by observations. There is still some remaining space on the left side of this graph which has been left free with WIMP models, so that the physicists flexibly invented new particles just to fill it, so that their experiments and grants can continue. There is no deeper logic in it - the mainstream physics today simply works in this dumb opportunistic way.
howhot3
5 / 5 (3) Dec 04, 2017
I'm skeptical about this SIMP idea. To sum it up, they are proposing a PION like particle made up of two quarks (a quark and anti-quark) that has influence over on matter that mimics an addition gravity like force. It's not a Pion (U+U-) (D+D-) nor a (C+C-) or (S+S-). It would have to be a (T+T-) or a (B+B-). It also would have to be made in huge abundances of massive scale at the beginning of the Big Bang, and... and my friends... it would have to be super stable over 13.8 billions years to be as "dark" as it is.

Good try but, I still think the "Immersive Gravity" concept is where the actual physics is happening.
NoStrings
1 / 5 (4) Dec 04, 2017
"Of course we shouldn't abandon looking for WIMPs," Murayama said, "but the experimental limits are getting really, really important. Once you get to the level of measurement, where we will be in the near future, even neutrinos end up being the background to the experiment, which is unimaginable."

As long as universities are wasting millions on your research, by all means, don't abandon a gravy line. What are you going to do with your career, having it developed around a crackpot fantasy? Bills to pay, wimpy kids to raise.
howhot3
5 / 5 (6) Dec 04, 2017
Followup to @mackita, It's certainly not a waste of time for science to look at these suggestions. Just as a good detective story is loaded with clues, science is also a detective story. Without pursuing them it can be easy to miss the big one. So looking for a PION like heavy particle in an accelerator isn't a waste of time. It will be documented and noted (a published) if nothing is found. That is the scientific way. Its big science because it's a big question. What is causing "Dark Matter" Sorry I meant Emergent Gravity not "Immersive Gravity"

https://phys.org/...ark.html

fthompson495
1 / 5 (2) Dec 05, 2017
There is evidence of SIMPs every time a double-slit experiment is performed, as it is the dark matter that waves.
yep
1.7 / 5 (10) Dec 05, 2017
And there I was wondering how long it would take for someone to say 'plasma'


A universe composed of 99% plasma makes a lot more sense than the science we have now based in a theological assumption filled with imaginary nonsense.

To not consider the Electrical force as the prime mover over Gravity is laughable, but considering the article above there seems to be a lot of money in science fiction, especially the non-falsifiable kind.

dogbert
1.8 / 5 (5) Dec 05, 2017
We insist on finding dark matter. We have looked for over 70 years for dark matter without finding a single particle of it, but we want dark matter and we will find it or bust!

When you fail to find what your hypotheses predict, it is time to make different hypotheses.

We need to examine our models to see where they fail. The continual hunt for imaginary mass is counterproductive.
mackita
1.6 / 5 (7) Dec 05, 2017
Just as a good detective story is loaded with clues, science is also a detective story.
But we can solve it with good detective like Hercules Poirot or poor detective who admits correct explanation only when all other models get experimentally excluded one after another. I can even admit that some part of science wastes my money in projects ineffectively if only it wouldn't neglect the research of phenomena and findings, which would have a way more immediate utility, like the cold fusion. Unfortunately the current situation is, Big Science drains the money for smaller projects, not to say about these more useful ones. The purpose of Blue Skies research is to enable the applied research, not to prohibit it.
Benni
2.3 / 5 (6) Dec 05, 2017
When you fail to find what your hypotheses predict, it is time to make different hypotheses.


In the 1930's Fritz Zwicky predicted rocket engines would not be able to operate outside the atmosphere because rocket exhaust would have nothing in space "to push against" to create forward thrust. He then came up with the TIRED LIGHT Theory. After Einstein & a few other real scientists made Zwicky look like an absolute dunce for those two failed theories, Zwicky went on a name calling binge labeling his detractors "spherical bastards".

So now Zwicky thinks he's really gonna show up these "spherical bastards" & invent halos of Dark Matter that surround all Spiral galaxies. Again he incorrectly interprets redshift data & predicts counter gravitational forces surrounding spirals keeping the spiral arms from imploding into the central hub. Bellows of laughter from real scientists followed.

This failed asstro-physicist is the icon of all DM Enthusiasts.
Merrit
5 / 5 (7) Dec 05, 2017
@yep problem with that is the electric force requires something to have a charge or the forces cancel out. Gravity, on the other hand does not. That is why at large scales gravity is going to be more powerful.
cantdrive85
2 / 5 (7) Dec 05, 2017
@yep problem with that is the electric force requires something to have a charge or the forces cancel out. Gravity, on the other hand does not. That is why at large scales gravity is going to be more powerful.

The ions and electrons in astrophysical plasmas retain their charges. Nothing "cancels out" in these domains, that is just a maths assumption. It is the electric force which holds galaxies together, not the magical imaginary faerie dust of fanciful pontificating plasma ignoramuses.
mackita
2.3 / 5 (3) Dec 05, 2017
Description from above image:
Conventional WIMP theories predict a highly peaked distribution, or cusp, of dark matter in a small area in the center of every galaxy. SIMP theory predicts a spread of dark matter in the center, which is more typical of dwarf galaxies.
I'd don't understand, why quarks should exist lone, being extremely unstable. And when they interact with gravity only (which is attractive force), how it could prohibit cusped distribution and concentrating dark matter? The SIMPs looks like theory proposed by average PO commenter. If I would propose something like this right here, I'd get ten downvotes at place.
Merrit
5 / 5 (5) Dec 05, 2017
@cantdrive most of the plasma is the stars. The solar wind, for instance, has a much higher charge to mass ratio so I wouldn't be surprised if electric forces play a part there. But, stars are relatively neutral in that we don't feel their charge here on earth. But, the suns gravity does play a big part here on earth. Are you making the assumption other stars in the galaxy do have a significant charge or are you just misunderstanding how the electric force works?
mackita
1 / 5 (3) Dec 05, 2017
Main author of the study - she is quite a chick. But her theory is so strangely nonsensical, that Sokal hoax comes on mind here (1, 2, 3).
Ironically quite recently the [theorists identified stable tetraquark](http://physicswor...raquark) composed of pion pairs which are hold together by Yukawa force (a short-distance analogy of Casimir force, enabled just by elongated character of pion particle).
Da Schneib
5 / 5 (3) Dec 05, 2017
To put a point on @howhot's posts, a quark+antiquark is a meson. The two quarks don't have to be the same species. Pions, for example, can contain two ups, or two downs, or an up and a down.
Merrit
2.5 / 5 (4) Dec 05, 2017
Considering all the limitations cosmology has such as not having spaceships that can go realistic velocities or ways to go ftl to observe and experiment for instance around massive objects such as black holes and neutron stars. We also have only had sophisticated technology to observe the universe for a relatively short period of time. Not to mention all from the same perspective, Earth. This leads to the limitation that GR has only been really tested at relatively low velocities and gravity wells. While we know relativity does a good job of predicting reality, the equations may be a bit off as we approach light speed or enter deep gravity wells. This is just another possibility for DM, not necessarily an issue with gravity at all. Also, the premise that all observes measure the speed of light the same in a vacuum is also an untested aspect of relativity. We don't have the technology to do the thought experiments that would prove it.
Da Schneib
5 / 5 (3) Dec 05, 2017
@Merrit, be careful here. We have tested both SRT and GRT a lot more carefully than you are implying here. Not only that but we can observe matter near BHs and NSs. Also the effects attributed to DM don't occur in the strong gravity limit; they're spread across galaxies and galaxy clusters. For MOND or some other non-GR construct to work GR has to be wrong in the weak limit, not the strong limit, so stating that we might not know what's going on in the strong limit isn't an argument against DM. Pick one: strong limit, weak limit. Don't expect them to be the same, they aren't for any other force.

As far as the speed of light in a vacuum being a constant we've been testing that for over a hundred years and no one, ever, has seen a deviation. High school kids do relativity experiments that show it. I don't give this much credibility.
Merrit
1.5 / 5 (2) Dec 05, 2017
@da Schneib then maybe you can answer a question about relativity for me. Take the classic example where they have a photon bouncing back and fourth in a spaceship so that the people in the spaceship and outside both see light traveling at light speed since the person outside sees the light moving at an angle. Now, instead of having the ship moving perpendicular to the observer, have it moving either towards or away at relativistic velocities. The issue with this scenario is that distance between the observer and object is changing over time. An object leaving at relativistic velocities will appear to be going in slow motion due to the change in distance and likewise a ship approaching will appear to be in fast forward if we were to compare it to watching a video. This is on top of all the relativistic effects we would expect from GR. Now, I don't see how in these cases how all observes would measure the same speed of light.
Da Schneib
5 / 5 (2) Dec 05, 2017
@Merrit this has all been done.

If the ship is moving toward you, the light takes longer to get to the more advanced position of the forward mirror, and shorter to get to the more advanced position of the back mirror. If it's moving away from you, vice versa. It's easy math to figure out how the distances vary, unless it's accelerating, and for that you need tensors and GRT, but we know how to calculate this.

Your problem here is you're trying to apply a relativistic correction to light; it doesn't apply. All observers see the speed of light in a vacuum as the same speed, c which is 299,792,458 m/s. What happens to the objects the light is interacting with is immaterial.
Merrit
1 / 5 (1) Dec 05, 2017
@da Schneib you aren't seeing the issue of the distance changing between the ship an us on earth. Take a different example. A ship travels at light speed for 10 years away from the earth then turns around and comes back. Two years from now we would see where the ship was a year ago because of the time it takes for the light to reach us. After 10 years we see where it was 5 years ago. We are effectively seeing the ship moving at .5c when it is actually going at c. Now at the 20 year mark we would see what appears to be the ship moving instantly from 10 light years out all the way back to earth again. This is the issue of changing distance between the observer and object and I don't see how this reconciles with relativity saying we all see light traveling at light speed when a ship just appeared to move much faster.
Da Schneib
5 / 5 (1) Dec 05, 2017
@Merrit the changing distance is immaterial. The light is not "moving with the ship." It's in free flight between the mirrors. This is a standard point most students of relativity get hung up on early on. The only points of contact between the light and the ship is the mirrors.
Merrit
1 / 5 (1) Dec 05, 2017
@da Schneib so the fact the ship appears to be going faster than light is not an issue?
Da Schneib
5 / 5 (1) Dec 05, 2017
@Merrit how do you figure the ship appears to be going faster than light? I will tell you in advance you're wrong, whether it's a postulate of yours or a result you think you have found. But that's not an insult; and I should be able to figure it out and explain it for you. How relativity changes the laws of motion you're used to isn't intuitive, especially not in terms of your experience with objects that move slowly.
cantdrive85
1 / 5 (4) Dec 05, 2017
@cantdrive most of the plasma is the stars. The solar wind, for instance, has a much higher charge to mass ratio so I wouldn't be surprised if electric forces play a part there. But, stars are relatively neutral in that we don't feel their charge here on Earth.

Yes, there is an assumption that stars will have a significant charge compared to their surrounding environment. And a similar idea is what can explain how galaxies don't fly apart relative to their rotation.
https://medium.co...6488ba0e

https://arxiv.org...409.3096

In other words, DM is not needed, just the correct application of the EM forces and fields involved.
Merrit
1 / 5 (1) Dec 05, 2017
@da Schneib well as a ship approaches at near light speed the light being given off will not take the speed of the ship, although it will be blue shifted. But, the ship is constantly moving closer so that the light given off over time has less and less distance to travel compared to light given off in the past. This is all very similar to breaking the speed of sound but with light rather than sound.

If it was moving perpendicular to you or say orbiting your location, there would be no change in the distance between you and the ship, then you would be able to properly see the effects of relativity that we would expect without further distortion.
Da Schneib
5 / 5 (1) Dec 05, 2017
@Merrit, how does the light being blue shifted change its velocity?

And what does the distance it travels have to do with its velocity?

Remember that the light only has contact with the mirrors, not with any other part of the ship.

Einstein has a classic discussion about all this in his book for non-physicists named "Relativity." It's one of the first discussions in the book. It involves a train rather than a spaceship, but all the same principles hold.
Merrit
1 / 5 (1) Dec 05, 2017
@da Schneib forget the mirrors. The ship just has a flashlight or headbeams turned on at its front.

From the perspective of us on earth, when the ship is 10 Ly out it will take 10 years for the light to reach us. A year later the ship is 9 Ly out and it takes 9 years for that light to reach us. A year later it is 8 Ly out and it takes 8 years for that light to reach us etc. As you can see, all the light will reach earth at the same time, including all the light in between. Like a giant sonic boom but have light rather than sound. Would blind you if you actually saw it.
Da Schneib
5 / 5 (1) Dec 06, 2017
@Merrit, doesn't matter how the light gets wherever. Everyone always measures it moving at the speed of light. The Lorentz transformation does that.

Your example doesn't show how either the light or the ship moves faster than light. Also, the ship can move arbitrarily close to the speed of light, but it can't move *at* the speed of light; it's made of matter and matter can't move at the speed of light.

Although your analysis is correct, it doesn't show anything moving at the speed of light but light, and it doesn't show anything moving faster than the speed of light.
Whydening Gyre
not rated yet Dec 06, 2017
@da Schneib forget the mirrors. The ship just has a flashlight or headbeams turned on at its front.

From the perspective of us on earth, when the ship is 10 Ly out it will take 10 years for the light to reach us. A year later the ship is 9 Ly out and it takes 9 years for that light to reach us. A year later it is 8 Ly out and it takes 8 years for that light to reach us etc. As you can see, all the light will reach earth at the same time, including all the light in between. Like a giant sonic boom but have light rather than sound. Would blind you if you actually saw it.

There would be quantifiable blue shift differences...
Merrit
1 / 5 (1) Dec 06, 2017
@da Schneib your conclusion is what I would expect. Well true, that it can't move exactly the speed of light, bit it could be close so that all the light arrives in the blink of an eye.

Now, this is the peculiar part. While you see ten years of your time pass in the blink of an eye, due to time dilation on their part, time has been passing slower for them. I would imagine these would have to exactly cancel out in order for relatively to hold.

But, now the issue I see is if the ship was moving away at near light speed, then due to the increase in distance it would only appear to be moving away at .5c and relativity would have time passing slower due to time dilation. In this case it would appear things are happening in slow motion. I don't see how this can reconcile with the case when the ship is approaching.
Da Schneib
not rated yet Dec 06, 2017
@Merrit, I'll give you a hint: you didn't specify whether the "one year between flashes" was in the timeframe of the observer watching, or in the timeframe of the ship.
cantdrive85
1 / 5 (2) Dec 06, 2017
The last handful of posts just goes to show the utter nonsense of GR and the standard theory.
mackita
1 / 5 (2) Dec 06, 2017
The theories are just approximations of reality, which may depend on scope. At the water surface the behavior of ripples also depends on scope. At small distance scales their spreading gets modulated by Brownian noise of the underwater, so that it gets probabilistic character. At larger distance they spread in regular circles in background independent way, so that for this range we can adopt another approximate theory, which neglects the background. At even larger distances this model will get broked again, but it doesn't make the approximate theory less relevant - just limited to its scope where it belongs.
Da Schneib
1 / 5 (1) Dec 06, 2017
@mac I don't really care what a #physicscrank has to say about relativity. It's like listening to a #biologycrank deny Darwin.
cantdrive85
1 / 5 (2) Dec 06, 2017
@mac I don't really care what a #physicscrank has to say about relativity. It's like listening to a #biologycrank deny Darwin.

Or listening to someone trying to convince the world he has found a magnetic monopole, like da schnied keeps claiming.
mackita
not rated yet Dec 07, 2017
Maggnus
5 / 5 (3) Dec 08, 2017
The last handful of posts just goes to show the utter nonsense of GR and the standard theory.


Cause it's easy to disparage something you do not understand but has been proven over and over again with both theoretical and observational evidence and instead speak gospel of Giant Magical Lightning Dolts that have never been seen, that have no theoretical backing, and that require a complete shift in the very physics it uses to try to prove itself.

Do you believe in faeries too? Probably not - there is actually more evidence for them then the Great Lightning Generator in the Sky.
mackita
not rated yet Dec 09, 2017
The Flyby anomaly is back and stronger than ever... Is this caused by Mundane Effects or New Physics?
mackita
not rated yet Dec 10, 2017
Mass constraints show that black holes are unlikely to explain dark matter: A new, stronger constraint on the hypothesis that primordial black holes comprise the totality of dark matter.. see also older article: Search for primordial black holes called off by Nature News.
BTW The proposal of cosmic strings, which were once hyped as one of ways which would enable testing the string theory didn't end way better by using data from the first Advanced LIGO observing run.

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