Finding dark matter in the dark

Finding dark matter in the dark
Credit: NASA, ESA and M. Montes (University of New South Wales)

Dark matter is the mysterious material that holds the Universe together, yet no one has seen it; or heard, smelled, tasted or touched it either.

But that may soon change, and a laboratory 1000 metres below the ground in the Stawell gold mine halfway between Melbourne and Adelaide could be the epicentre of this discovery.

Physicists have had a good run recently at detecting the seemingly undetectable. First there was the Higg's Boson, confirmed by experiments at the Large Hadron Collider in 2012, nearly 50 years after it existence was first proposed. Then in 2015 the LIGO detectors found gravitational waves, a century after Einstein predicted them. Both discoveries were rewarded with Nobel Prizes.

If all goes to plan, in the next few years dark will move from the realm of the hypothetical to the observable, opening a new era in experimental physics, and a major step towards a fundamental theory of nature.

Professor Elisabetta Barberio is leading the Australian effort to detect dark matter, as the Director of the Centre for Dark Matter Particle Physics. The University of Melbourne physicist says Australia is uniquely positioned to confirm the existence of dark matter.

How do we know what we are looking for?

Finding dark matter in the dark
Cosmic rays are absorbed by rock so if you go deep enough in the Stawell mine (pictured) you can reduce these to almost zero. Credit: University of Melbourne

It started with some simple calculations based on Newton's Law of Gravity.

"If I look at the solar system, there's the sun and all the planets, and if I know the velocity of a planet and its distance from the sun, I can calculate the mass of the sun," says Professor Barberio.

"We can do the same with our galaxy. We can take the motion of a star, and, knowing the distance of the star from the centre of the galaxy, we can calculate how much material there is in the galaxy.

"When we do this calculation, the amount of material that we see and the amount of material that should be there by our calculations don't match. Our calculations say that there is much more material in the galaxy than what we can see. And this is dark matter."

Physicists think dark matter is made up from an as-yet-unknown fundamental particle that has no electric charge, doesn't produce light, and doesn't interact very much with anything. But they also think that there will be the occasional interaction that we could perhaps detect, given the right equipment and the right location.

"We know that there is a lot of dark matter in the galaxy – between 70 and 80 percent of the material in the galaxy is dark matter," says Professor Barberio, "and so every second our bodies are traversed by billions of these dark matter particles that don't do anything to us. We are transparent to these particles."

Finding dark matter in the dark
Starburst in a Dwarf Irregular Galaxy. Credit: NASA, ESA, Hubble Heritage (STScI/AURA)
"However, we think that very, very rarely, a dark matter particle interacts with the nucleus of an atom in a material that we can see – what we call normal matter."

The problem is that other things also interact with the ; notably and radioactivity.

"The probability that dark matter interacts with my nucleus is one event per 10 kg of material per day," says Professor Barberio. "The probability that radioactivity or cosmic rays interact with my nucleus is 10 billion times per 10 kg of material per day."

In other words, 1 in every 10 billion of these interactions is dark matter, making it impossible to distinguish any signal from the noise.

Going underground

To improve those odds we need to reduce the number of other interactions occurring. The first step is to head underground – way underground. Cosmic rays are absorbed by rock so if you go deep enough you can reduce these to almost zero.

Finding dark matter in the dark
Representation of the SABRE dark matter detector. Credit: University of Melbourne
"By going underground we've already eliminated a few billion interactions," says Professor Barberio.

"And then we also need to eliminate all the residual radioactivity in the material we build our detector from, because even if we take a banana into our lab, it will have so much radioactivity that there will be a few counts, a few interactions, per day, with my nuclei, and it will shade dark matter."

"We choose the right material, or build a material with very low radioactivity, and then we construct our detector underground and we start waiting, and count how many times there is this interaction."

Several underground dark matter detectors exist, and one even claims to see dark matter. The Gran Sasso Laboratory, built inside a mountain in Italy, tracks what they say is the annual modulation of dark matter arriving on Earth.

As the Earth goes around the sun, its velocity with respect to the centre of the galaxy changes. In June the Earth is travelling around the galaxy at about 260 km per second, whereas in December it is more like 200 km per second. Therefore we would expect the Earth to be hit by more dark matter in June than in December. And this is what the Gran Sasso team observes in their data.

"If you are on a bicycle and you go faster or slower you have more or less wind," says Professor Barberio.

Searching for Dark Matter. Credit: Swinburne University
Australia's dark matter detector

Seasonal changes, from summer to winter, could also lead to a cycle in the rate of interactions on the dark matter detectors. And this is where Australia comes in.

To remove this potential error, we need to repeat the experiments in the Southern Hemisphere, where the seasons are flipped. If we see a seasonal pattern, with a peak in summer and a minimum in winter, then the data from Italy needs to be rethought. If we see the same annual pattern, however, with a peak in June and a minimum in December, this could be the evidence that finally confirms the existence of dark matter.

The Stawell gold mine in western Victoria is one of the few places in Australia that can house a dark matter detector.

"You need to find a very deep mine or a very high mountain," says Professor Barberio.

"We don't have very high mountains so we needed to find a mine. There are very few mines in Australia that have the necessary depth and the necessary access. Thankfully, we have great support from the mine owners and the local Stawell community for our laboratory."

Professor Barberio's team hopes to have the Stawell Underground Physics Laboratory will be up and running this year. This will be the first dark matter detector in the southern hemisphere, and, when combined with data from other detectors around the world, could finally confirm the existence of .


Explore further

3 knowns and 3 unknowns about dark matter

Citation: Finding dark matter in the dark (2019, March 7) retrieved 18 June 2019 from https://phys.org/news/2019-03-dark.html
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Mar 07, 2019
Dark matter is a supersolid that fills 'empty' space, strongly interacts with ordinary matter and is displaced by ordinary matter. What is referred to geometrically as curved spacetime physically exists in nature as the state of displacement of the supersolid dark matter. The state of displacement of the supersolid dark matter is gravity.

The supersolid dark matter displaced by a galaxy pushes back, causing the stars in the outer arms of the galaxy to orbit the galactic center at the rate in which they do.

Displaced supersolid dark matter is curved spacetime.

In the Bullet Cluster collision the dark matter has not separated from the ordinary matter. The collision is analogous to two boats that collide, the boats slow down and their bow waves continue to propagate. The water has not separated from the boats, the bow waves have. In the Bullet Cluster collision the galaxy's dark matter displacement waves have separated from the colliding galaxies, causing the light to lense.

Mar 07, 2019
This idea posits a new hypothesis about gravity; it would explain the effects attributed to dark matter and dark energy.
It would also explain the odd behavior of Oumuamua, the interstellar asteroid that recently passed through our solar system. I paste an abstract here along with a link to my article on this.

ABSTRACT

Galactic rotation rates, the distribution of matter in the early universe shown by the scale of anisotropies in the CMB, and cosmological expansion present problems that current theory attempts to resolve by positing dark matter and dark energy. This paper posits that gravitational force is a dampened wave function dependent upon mass and distance. Therefore gravity reverses at regular dampened intervals. This reversal would also be in effect at smaller scales such as our own solar system, implying that current theory may have overlooked evidence of this in the data from various probes that have been launched.

LINK: https://redd.it/ao8vfo


Mar 07, 2019
In search of black holes and dark matter astrophysicists are relying on indirect observations. It would seem that the measurement of the event horizon of a black hole directly would be a direct evidence. However, by the nature of a horizon, any real measurement of the event horizon will be indirect. The Event Horizon Telescope will get picture of the silhouette of the Sgr A* which is due to optical effects of spacetime outside of the event horizon. The result will be determined by the simple quality of the resulting image that does not depend on the properties of the spacetime within the image. So, it will be also indirect and an existence of BH is a hypothesis.
https://www.acade...ilky_Way
https://www.acade...k_Energy

Mar 07, 2019
Then in 2015 the LIGO detectors found gravitational waves, a century after Einstein predicted them. Both discoveries were rewarded with Nobel Prizes.


So much for scientific accuracy. Einstein did not predict Gravitational Waves, it was first suggested by Poincare. Einstein's General Relativity implied their existence but Einstein did not believe it. Others continued to suggest it and in 1916, not 1915, Einstein tried to show that gravitational waves were not possible but his math indicated two possible forms. Errors in his math was corrected by others in 1922. Einstein again tried to disprove Gravitational Waves in the 1930s with a Russian Physicist but just before publication errors were found in Einstein's math and the paper ended up making the opposite conclusion.

Thus to say that Einstein predicted Gravitational Waves is factually and Historically false, why do amateurs keep repeating this meme? It is wrong: look it up!!!

Mar 07, 2019
"When we do this calculation, the amount of material that we see and the amount of material that should be there by our calculations don't match. Our calculations say that there is much more material in the galaxy than what we can see. And this is dark matter."

The reason the calculations don't add up is because the inherent gravity fields that EM Waves exert as they travel through interstellar space is incalculable.

Most people do not think of an EM Wave as also being a carrier of gravity, it is transformed mass & when mass transforms to energy & mass that is lost during transformation results in a proportional loss of gravity to the system losing mass, and is carried away by the EM Wave.

Every EM Wave photon tugs away at whatever is closest to it. Calculate all the EM Wave photons presently in existence in the Universe & add up all that inherent gravity, it would be sizeable. I've never yet seen calculations for estimating what the total of of that gravity would be.

Mar 07, 2019
The reason the calculations don't add up is because the inherent gravity fields that EM Waves exert as they travel through interstellar space is incalculable.

Most people do not think of an EM Wave as also being a carrier of gravity, it is transformed mass & when mass transforms to energy & mass that is lost during transformation results in a proportional loss of gravity to the system losing mass, and is carried away by the EM Wave.

Every EM Wave photon tugs away at whatever is closest to it. Calculate all the EM Wave photons presently in existence in the Universe & add up all that inherent gravity, it would be sizeable. I've never yet seen calculations for estimating what the total of of that gravity would be.
Yeah, but...
aren't photon's massless, therefore the reason they can travel at C?
(Its an interesting supposition, tho)

Mar 07, 2019
Every EM Wave photon tugs away at whatever is closest to it. Calculate all the EM Wave photons presently in existence in the Universe & add up all that inherent gravity, it would be sizeable. I've never yet seen calculations for estimating what the total of of that gravity would be.


Yeah, but...
aren't photon's massless, therefore the reason they can travel at C?
(Its an interesting supposition, tho)


EM Wave photons being transformed mass have a mass equivalence of inherent gravity.

Gravity lost to mass during MASS TRANSFORMATION to energy doesn't just sort of disappear never to show up again anywhere in the Universe, it is carried off in the EM Wave.

Mar 07, 2019
Gravity lost to mass during MASS TRANSFORMATION to energy
I don't even know what that means, much less where you claim someone said it.

You're lying again, @Benni.

Mar 08, 2019
Every EM Wave photon tugs away at whatever is closest to it. Calculate all the EM Wave photons presently in existence in the Universe & add up all that inherent gravity, it would be sizeable. I've never yet seen calculations for estimating what the total of of that gravity would be.


Yeah, but...
aren't photon's massless, therefore the reason they can travel at C?
(Its an interesting supposition, tho)


EM Wave photons being transformed mass have a mass equivalence of inherent gravity.

Gravity lost to mass during MASS TRANSFORMATION to energy doesn't just sort of disappear never to show up again anywhere in the Universe, it is carried off in the EM Wave.

Kinda like burning a pile of wood...?

Mar 08, 2019
Every EM Wave photon tugs away at whatever is closest to it. Calculate all the EM Wave photons presently in existence in the Universe & add up all that inherent gravity, it would be sizeable. I've never yet seen calculations for estimating what the total of of that gravity would be.


Yeah, but...
aren't photon's massless, therefore the reason they can travel at C?
(Its an interesting supposition, tho)


EM Wave photons being transformed mass have a mass equivalence of inherent gravity.

Gravity lost to mass during MASS TRANSFORMATION to energy doesn't just sort of disappear never to show up again anywhere in the Universe, it is carried off in the EM Wave.

Kinda like burning a pile of wood...?
......yeah, kinda like the smoke carrying away mass that was once in the wood pile.

Mar 08, 2019
"a laboratory 1000 metres below the ground in the Stawell gold mine halfway between Melbourne and Adelaide"

-Or you could go ask this guy

"Dr. Randell Mills holds a Doctor of Medicine degree from Harvard University and a BA degree in Chemistry from Franklin and Marshall College. He began his research on the unified field theory while studying electrical engineering at MIT. He has published widely and filed patents in the areas of hydrogen energy technology; magnetic resonance imaging; Millsian computational chemical design technology based on The Grand Unified Theory of Classical Physics (GUT-CP), a revolutionary approach to solving atomic and molecular structures..."

-His lab is at street level.

Mar 08, 2019
"a laboratory 1000 metres below the ground in the Stawell gold mine halfway between Melbourne and Adelaide"

-Or you could go ask this guy

"Dr. Randell Mills holds a Doctor of Medicine degree from Harvard University and a BA degree in Chemistry from Franklin and Marshall College. He began his research on the unified field theory while studying electrical engineering at MIT. He has published widely and filed patents in the areas of hydrogen energy technology; magnetic resonance imaging; Millsian computational chemical design technology based on The Grand Unified Theory of Classical Physics (GUT-CP), a revolutionary approach to solving atomic and molecular structures..."

-His lab is at street level.


And he's a crank.

Mar 08, 2019
Doctor of Medicine?

That one I didn't know. How the hell does that qualify him to do research on unified field theory? What's next, he's going to announce his new theory of how to see your taint without a mirror? Maybe a new theory of economics?

Mar 08, 2019
What part of "friction heats stuff up, and hot stuff emits light" does anyone suppose @Benni doesn't get?

Mar 08, 2019
....new theory of how to see your taint without a mirror?...

WHOA!
Da Schitts, the "meat" loving, knob gobbler, brays.
Hey Da Schitts, there is such a thing as, too much information, you know.

Mar 08, 2019
How do you even wipe your ass, never mind eat without stabbing yourself in the face with the fork?

Never mind. Too much information.

I am irresistibly reminded of the moron who stuck the ice cream cone on its forehead.

Mar 08, 2019
Kinetic Energy is invisible not dark

Energy that is dark, was thought to be dark, is not dark
energy is invisible, in momentum, in kinetic energy, is invisible
kinetic energy is not dark
because
we cannot see kinetic energy
because
kinetic energy is like glass, it is transparent
kinetic energy does not increase inertial mass
as kinetic energy doubles inertial mass stays the same
all the mass in this vacuum is in motion
electrons and protons are also in motion
the majority of mass has been converted into kinetic energy
through that enigmatic formula E = M.C²

Mar 08, 2019
I have no idea what "kinetic energy is dark" means.

We can measure it.

Sounds a lot like "time doesn't exist" to me.

Mar 08, 2019
As we discuss energy that is not dark

What we have to contend with
is
a Trollian under his bridge
TrollianDaSchneib, undergoing his ablutions
the councils in these Shires
for some time now
it has been
the rule
all animals
have to accompanied by adults
to carryeth the doggy bags
as this includes Trollians, when accompanied by their owners
so
that Trollians such as TrollianDaSchneib
do not mess up these thatched country Shire lanes
so
that the lucky few, who own these million $$$$ thatched cottages who have bridges over babbling brooks
the owner of TrollianDaSchneib is beholden by the Shire councils to attend to their Trollians
and where necessary clean their Trollians and dispose responsibly in doggy bags in the doggy bins provided

Obviously these Shire Trollians are well kept, clean and well fed
Not so the scruffy ragamuffin street fouling TrollianDaSchneib variety!

Mar 08, 2019
But you don't seem to have linked any sources or papers about kinetic energy.

I mean, just sayin'.

Is all that mangled syntax supposed to cover that up?

Mar 08, 2019
Kinetic Energy is invisible not dark
TrollianDaSchneib > I have no idea what "kinetic energy is dark" means

The reason, TrollianDaSchneib you have no idea what "kinetic energy is dark" means
is
because, TrollianDaSchneib it was said - Kinetic Energy is invisible not dark

Your Trollian eyes are not human eyes, TrollianDaSchneib
Trollian eyes along with eye finrot
suffer all sorts of biological problems
that effects the eyes
as
only Trollians can see words in sentences that are not actually there
these are sure and certain signs of your Trollan ragamuffin street urchin Trollian pedigree
These shire trollians are sleek, groomed, clean, well fed and if there is any finrot outbreak
These sleek trollians are taken to the veterinary for their finrot inoculations
So they do not suffer reading problems in their English lessons
You obviously have not had your finrot inoculation TrollianDaSchneib
Your eye sight is being affected

Mar 08, 2019
But you said "kinetic energy is dark."

I mean, just sayin'.

You changing your story now?

Mar 08, 2019
Kinetic Energy is invisible not dark

TrollianDaSchneib
Da Schneib > But you said "kinetic energy is dark."

I mean, just sayin'.

You changing your story now?

It was yourself, TrollianDaSchneib
that said kinetic energy is dark
and no one else

Mar 08, 2019
Only Trollians can see words in sentences that are not actually their

If a Trollian, TrollianCastroGiovanni repeats what TrollianDaSchneib said
The rule is
It was not TrollianCastroGiovanni that said it
It was TrollianDaSchneib what said it
That is the ruleth

Mar 08, 2019
Only Trollians can see words in sentences that are not actually their


Their what? Or did you mean 'there'?

Mar 08, 2019
Kinetic Energy is invisible not dark

Obviously, TrollianCastroGiovanni
Only Trollians can see words in sentences that are not actually their

Their what? Or did you mean 'there'?

You need to, TrollianCastroGiovanni
give
TrollianDaSchneib the benefit of your Trollian English lessons
as
TrollianDaSchneib also needs to eat his carrots
and
A change of surroundings works wonders
For a fresh out look
Well, for a short while at least
Until the mirages start all over again
In "kinetic energy is dark."

Kinetic Energy is invisible not dark

Mar 09, 2019
That one I didn't know. How the hell does that qualify him to do research on unified field theory? What's next, he's going to announce his new theory of how to see your taint without a mirror? Maybe a new theory of economics?
Well, as his hydrino/dark matter conversion is apparently a chemical process (involving electrons no?), his BA chem is more applicable.

BTW WTF is a taint?

Mar 09, 2019
Their what? Or did you mean 'there'?
You can tell how small someone is when they spellcheck.

Mar 09, 2019
That one I didn't know. How the hell does that qualify him to do research on unified field theory? What's next, he's going to announce his new theory of how to see your taint without a mirror? Maybe a new theory of economics?
Well, as his hydrino/dark matter conversion is apparently a chemical process (involving electrons no?), his BA chem is more applicable.

BTW WTF is a taint?


There are no hydrinos. They do not, and cannot, exist. It is a scam.

Mar 09, 2019
I have no idea what "kinetic energy is dark" means.

We can measure it.

2+2/2

Mar 09, 2019
Equals what, @Benni?

You've just said "two plus two over two."

That's equivalent to saying "My horse is a."

Mar 09, 2019
Castro- a Portuguese and Spanish-Galician surname coming from Latin castrum, a fortification.

giovanni- Italian forrn of John 'God is gracious''God has shown favor.'


Mar 09, 2019
When a Trollian goes trollianing
Benni> Castro- a Portuguese and Spanish-Galician surname coming from Latin castrum, a fortification.

giovanni- Italian forrn of John 'God is gracious''God has shown favor.'

Benni, concerning St Jones
if you have not already noticed
it is barely 7 days hence
and our site trollian, TrollianCastroGiovanni
has all ready taken it on himself in trolling innocent commentators
and
Issuing forth abusive trollians that in time will become trollians most foul

Mar 09, 2019
When a Trollian goes trollianing
Benni> Castro- a Portuguese and Spanish-Galician surname coming from Latin castrum, a fortification.

giovanni- Italian forrn of John 'God is gracious''God has shown favor.'

Benni, concerning St Jones
if you have not already noticed
it is barely 7 days hence
and our site trollian, TrollianCastroGiovanni
has all ready taken it on himself in trolling innocent commentators
and
Issuing forth abusive trollians that in time will become trollians most foul


St Jonesy.........Ah yes, these gifts we have been given from ABOVE. Or are these giovanni jonesies just those from another planet trying to fool us into thinking their flying saucers are "chariots of the gods"? Incarnate jonesies hiding behind a name.

Mar 11, 2019
This article is good as a shout out for SABRE but it is not a good presentation as it omits technical detail and it is pretty bad on the dark matter context. The initial observations of dark matter are nearly a century as well (Kapteyn and Oort suspected it, Zwicky discovered it) and today we can observe it by many independent means.

The article seems to discuss putative weakly interacting massive particles (WIMPs) for dark matter, but those that was expected to be found at "natural" energies beyond the standard particle energy range has recently nearly been eliminated due to the ACME experiment on electron sphericity. And it seems Barberio also wants to make a shout out for the Italian Gran Sasso experiment, which signal is now believed by most physicists to have been caused by seasonal radioactivity derived helium leaks into their detectors.

Mar 11, 2019
@torbjorn, I am currently leaning toward "WILPs" Weakly interacting light particles. The neutrino sector attracts my attention.

Mar 11, 2019
Hi Da Schneib. Been reading up on Baryon Asymmetry, that big glitch in the Big Bang. I got into this after reading some guy post what he defined as "absolute fact" about events that must have occurred in the earliest moments of the Big Bang based on the background radiation.

It got me wondering about the Big Bang from the get-go - how do cosmologists get around Baryon Asymmetry since it throws a big wrench into the whole theory? And a big wrench in any big "theory" changes "absolute facts" into absolute speculation. At least most scientists would draw this conclusion.

I know that some people are looking for antimatter galaxies, hoping to discover that it was annihilation that was asymmetric.

My main issue is how can all these cosmologists sweep Baryon Asymmetry under the rug and just go on speculating about the origin of matter etc. as if nothing was out of the ordinary? Any ideas other than defining the type and size of cosmic brooms and their value in scientific research?

Mar 11, 2019
you don't seem to have linked any sources or papers


The whole thread was wasted on cranks who, of course, cannot link to peer reviewed research or stay on topic (the article) but endlessly spout their gibberish. The often massive down voting should clue them in that most readers can recognize a crank within a few words (or on this site by their handles) and junk it. What is claimed without evidence can be dismissed without evidence.

But of course something is massively wrong in their behavior, so they may not be able to recognize that.

Maybe I should source my own comment to show how easy it should be. Ref to ACME through here: https://www.forbe...y-round/ .

Mar 11, 2019
@torbjorn, I am currently leaning toward "WILPs" Weakly interacting light particles. The neutrino sector attracts my attention.


The already known neutrinos cannot be it, but there is a possibility of a "sterile" kind. So sure, possibly.

It got me wondering about the Big Bang from the get-go - how do cosmologists get around Baryon Asymmetry
.

So they do not, they have identified a likely pathway *how* it can happen, but it is still an open question [ https://en.wikipe...ogenesis ]. This is in no way a do-or-die problem for the accepted cosmology (or it would not be accepted), it is more of a separate problem since expansion, inflation, et cetera fits.

And in fact there are clues. While the standard particle sector does not have sufficient CP violation the neutrino sector has so far (at still high uncertainty) observations of precisely the necessary amount. Within 5-10 years the coming neutrino experiments should tell us that at least.

Mar 11, 2019
Thanks for your comments, @torbjorn.

But they do not get to the core of that major flaw in that biggest theory. Many people use some observations as diamond hard facts - e.g., from the background radiation. Major flaw(s) in the Big Bang theory might suggest there are flaws in the interpretation of those observable results as well.

Agreed that some things fit the theory as you noted. Many theories have this going for them, but do not always cement the case or conditions.

That is the problem with cosmology and all things so far away. You can only look at phenomena and make conjectures. Empirical evidence is soooo minimal. All of you have my deepest sympathies in this regard.

But no one can yet explain that major flaw........pathways are usually theories themselves.

Does anyone really think there are antimatter galaxies, and how would you prove them to be so?

Mar 11, 2019
The pathways you refer to in that link are listed below:

"..... it is puzzling that the universe does not have equal amounts of matter and antimatter. Indeed, there is no experimental evidence that there are any significant concentrations of antimatter in the observable universe.

There are two main interpretations for this disparity: either the universe began with a small preference for matter (total baryonic number of the universe different from zero), or the universe was originally perfectly symmetric, but somehow a set of phenomena contributed to a small imbalance in favor of matter over time. The second point of view is preferred, although there is no clear experimental evidence indicating either of them to be the correct one. "

cont.

Mar 11, 2019
cont.

Or even if EITHER of them are correct. They look a bit like hand-waving to me. As remarked
in a 2012 research paper, "The origin of matter remains one of the great mysteries in physics."

The point I am making is that all or most of these postulates, particularly grand scale stuff, are actually based on the Big Bang theory as fact in every respect. Hard to accept a theoretical pathway for some divergence from this grand theory.

Are there any more such Big Divergences from the Big Bang theory? Don't be shy, now!


Mar 11, 2019
.

Does anyone really think there are antimatter galaxies, and how would you prove them to be so?


Given that galaxy mergers are relatively common, then what would we see when an antimatter galaxy collided with a normal galaxy? It'd be pretty obvious I would think. And spectacular. And long lived.

Mar 11, 2019
Quite true @Castrogiovanni, but one always reads about how the distance between stars are so vast that two galaxies could merge without any stars colliding. If any annihilation takes place, one would guess it would be on a small scale and/or over very long periods.

I would agree that if it occurred on a large scale, it would likely be spectacular. Since there are so many galaxies and an equal need for antimatter galaxies, one should think at least one merger is occurring right now. But you might need to live a long time to see anything happen.


Mar 11, 2019
@Da Schneib
@torbjorn_b_g_larsson.

From @Da Schneib to @torbjorn:
I am currently leaning toward "WILPs" Weakly interacting light particles. The neutrino sector attracts my attention.
From @torbjorn to @Da Schneib.
The already known neutrinos cannot be it, but there is a possibility of a "sterile" kind. So sure, possibly.
Very interesting, guys. :)

FYI, I already pointed out that cumulative Neutrino mass over trillions of years might be one component/factor in the observed dark matter mass/effects. See my post in:

https://phys.org/...ton.html

Unfortunately, some of your 'friends' DOWNVOTED ME for pointing out what both of you agree is reasonable suggestion/possibility!

ps: Maybe your 'friends' who downvoted me (when I pointed out that reasonable suggestion/possibility) were more concerned with their OWN subjective personal animosity against the 'messenger' than the objective 'message', hey guys? :)

Mar 11, 2019
Wow, @dfj, you went on a real tear! I'll try to crank some answers out but it's gonna take a little while.

@torbjorn has given you a pretty good answer, but I'll amplify it a bit. But first let me respond to his recent post to me.

First, there's some things called the "Sakharov criteria" that must be met for there to be a matter-antimatter imbalance, also called the "Sakharov conditions." They're in the Wikipedia article @torbjorn linked for you on baryogenesis. Look them over while I answer @torbjorn.

Mar 11, 2019
@torbjorn, yes, sterile neutrinos are what I was thinking of. Axions also remain a possibility. The longer we go and keep not finding WIMPs, the better other hypotheses start looking. The gravity wave detections, particularly GW 20170817 which allowed direct comparison of the speeds of light and gravity, have really torn up the field approach, just about killing MOND off because of it predicting a difference. There remain some other field approaches, but I'm not sure about whether they too predict such a difference, so they may not be affected quite so much.

Did I miss any possibilities you know of?

Mar 11, 2019
@dfj, OK, first, baryon asymmetry is under investigation, but because we can actually see the residual radiation from the Big Bang, it's pretty hard to deny it, and also because we can see all the galaxies receding from each other very early in the universe, as they do today. Baryon asymmetry is insufficient grounds to challenge the Big Bang.

So let's start with CPT symmetry and what CPT means, because this is key to understanding antimatter.

CPT stands for Charge, Parity, and Time. In antimatter, all three of these are reversed from normal matter.

Charge is easy; primarily it means electric charge, but it also means color charge (like quarks have). So a blue down quark's antiquark is antiblue, and also has an electric charge of +1/3 instead of the -1/3 of the down quark. The weak charge reversal is too complex to go into here, and unnecessary as well; suffice it to say it also is reverse in antimatter.

[contd]

Mar 11, 2019
[contd]
Parity is a bit harder to explain; some particles have spatial asymmetry, also called handedness or chirality. So, for example, if you use a magnetic field to align neutrons (yes, you can do that- their quark composition, ddu, guarantees that they will always have an electric charge imbalance which can be affected by a magnetic field) and then watch what direction the proton and electron come out when the neutrons decay, you will find that there is a preference for a particular direction. Neutrons, then, are chiral. In an antineutron, this directional preference is reversed. It's worth noting that most if not all of the chirality displayed by particles is in their weak force interactions.

Finally, time. Time, like the more familiar 3 dimensions of space, is a dimension. So although we often talk colloquially about "time passing," in fact, it does not. Instead, matter moves through time. And antimatter moves in the opposite direction in time from matter.
[contd]

Mar 11, 2019
I see this in that wiki link from @torbjorn:

"In the out-of-equilibrium decay scenario, the last condition states that the rate of a reaction which generates baryon-asymmetry must be less than the rate of expansion of the universe. In this situation the particles and their corresponding antiparticles do not achieve thermal equilibrium due to rapid expansion decreasing the occurrence of pair-annihilation. "

Have read other articles suggesting any observable antimatter would likely be in the distant universe, when it was presumably more prevalent (from "cosmic inflation"). My readings suggest most of it should have been destroyed in the initial stages of the Big Bang (pre star-light) - i.e. inflation might not have spared so many baryons. Some antimatter is apparently produced in cosmic events near and far (e.g. relativistic jets).

NASA is trying to determine if such galaxies exist by looking for X-ray and gamma-ray signatures of annihilation events in colliding superclusters.

Mar 11, 2019
[contd]
Now, how are these (CPT) linked?

The answer is, by a symmetry called the Lorentz invariance, which is part of SRT, plus some pretty complex quantum physics called the Hermitian Hamiltonian. And if weak charge reversal was a bit much, Hermitian Hamiltonians are your good buddy calling you up and asking if you want some carrots, you say "yes," and the next thing you know you hear a dump truck backing up into your driveway. Beep beep beep.

Lorentz invariance, it is important to note, is SRT; that is, it doesn't involve gravity.

So the upshot is, CPT symmetry is a basic "built in" symmetry of the universe, and it's connected with the four dimensions. How do we know this for sure? The answer turns out to be the laws of spin and statistics, which act on the spins of particles. Because of these laws, two particles of matter cannot occupy the same space at the same time; whereas two particles of energy not only can but prefer to.
[contd]

Mar 11, 2019
Firstly I am not second guessing the Big Bang, or the radiation. Hubble's Law is very compelling for a cosmic scale Bang. My biggest problem is in using anomalies within the background radiation to arrive at "facts" as opposed to suggestions.

I also understand the CPT and those aspects of annihilation.

Will return to your opening statement that "baryon asymmetry is under investigation". You are writing something and posting it now so I will wait for more.

Mar 11, 2019
[contd]
Everyone is familiar with the adage that two objects cannot occupy the same space at the same time; but this effect on energy particles is less familiar. It is called "coherence," and can be observed in laser beams, where all the photons occupy very nearly the same energy state. So this isn't just some theoretical thing; we can actually observe it.

And this proves CPT symmetry experimentally.

OK, now we've covered antimatter: it's matter, CPT reversed.

Now, if two of C, P, and T can be reversed, then the universe can exist (and can come to exist) with different amounts of matter and antimatter.

So, can this happen, and can we detect it?

Yes.

CP violation was detected in the 1960s in neutral kaon decays; "kaon" is the modern terminology, but originally these were "K mesons." It turns out that kaons with no electric charge can decay by two different interactions; theoretically they should be equal, but they are not.
[contd]

Mar 11, 2019
[contd]
And this CP asymmetry is also seen in the B and D mesons.

So now we have CP asymmetry in the quark sector; do we also see it in the lepton sector?

The answer is "yes," and it's confirmed experimentally in weak interactions in the leptons.

So now we have CP violations, but no CPT violations.

And you will note that this is the second of the Sakharov criteria.

Furthermore, the first criterion has also been confirmed; U(1) non-perturbative anomalies in the SM show C-symmetry violation.

The third criterion is easily confirmed; we see it from the simple fact of the recession of galaxies from one another in the early universe.

As @torbjorn says, quark sector CP violations are insufficient; but when added to lepton sector CP violations. it's looking like it's enough.

The current task is to identify and quantify these violations of CP symmetry and make sure they are sufficient to account for baryogenesis and the lack of antimatter.

Mar 11, 2019
OK, that answers your baryon asymmetry argument against LCDM cosmology. I'll take on the rest in a bit.

Mar 11, 2019
The intergalactic medium (IGM) is sufficient to show there are no antimatter galaxies. They simply cannot exist without interactions with the IGM that send gamma rays from the matter-antimatter annihilation that would have to happen either if the IGM were antimatter and the galaxies were annihilating with it, or if antimatter galaxies annihilated with the matter IGM. We could not possibly miss these annihilation events in gamma ray telescopes currently deployed in Earth orbit. Their spectra are well defined and would appear as spectral lines in gamma spectroscopy. They do not.

And that's leaving aside @Castro's point about colliding galaxies; we'd see the same gamma spectral lines from them too, even if stars don't collide; that's because galaxies are as much dust and gas as they are stars. It is inevitable that the gas and dust would collide and form these gamma spectral lines, and they do not.

Mar 11, 2019
To be sure I am not suggesting such galaxies, only that they were used as a possible explanation for the asymmetry theory. Your posts demonstrate quite well that baryon asymmetry need not be locked into a Big Bang Glitch.

And, I am not questioning the fundamentals physics behind this, but rather the "perception" of events which gave rise to the current state. I am extremely skeptical of some of the "facts" that people derive from their equations, which are usually based on a severely limited data set.

Cont.

Mar 11, 2019
While you have given a great overview, and changed my notions on the mechanism(s) of baryon asymmetry, in the end it does not address the primary issue I brought up regarding the background radiation on which so much of Big Bang "theories" are based.

Not the event itself. but what happened during and "shortly" after. It seems like an impossibility to project, from what it looks like now, back 13.8 billion years when you have no idea regarding the amount of annihilation and other sources of radiation DURING the Big Bang. Its like mixing up a bunch of species of road kill and trying to sort them all out after it has been shredded and minced for fish food.

Indeed, all of what you have described makes it seem even more unlikely that all of the details of the early stages of the Big Bang can be defined by its ancient radiation. It seems to me that speculation will have to suffice as unequivocal empirical evidence will be forever lacking.

Mar 11, 2019
@dfj, you've been consistently asking good questions that deserve detailed answers. I don't regret a moment it's taken me to answer them.

I think you should consider the totality of the evidence and the scope of it; this is a combination of theory and experiment and observation that it is very difficult to deny.

With very nearly known mechanisms that can explain baryon asymmetry currently under research and looking really good, I'm not sure I understand what your objection is. You certainly know that asserting uncertainty is not sufficient. Ask your question directly.

Mar 12, 2019
Apart from Hubble's law, the background radiation (BR) is highly referenced to indicate a Big Bang. Correct if I am wrong, but the BR is the only thing one can actually look at, and attempt to pry "answers" from the initial moments of this Bang.

But since the amount and type of radiation from this event is so variable (IR, UV-VIS, X-rays, gamma, etc.), it is difficult to understand how one can demonstrate various aspects of the Bang as it progressed. For instance, someone noted that the BR tells us only 'so much hydrogen could be present in the observable universe'. Stated it as a matter of fact, and that the BR "data" at 300,000 years "post bang" proves it. This is a good one actually since you are on top of this stuff. It seems to me impossible to sort out such information from the complex BR.

Do you expect to find such details in the BR, after "sorting" it all out?

And if antimatter is going back in time, wouldn't it disappear as soon as it forms?

Mar 12, 2019
The CMB is microwave. The reason the CMB tells the hydrogen content of the universe is because it shows what the concentration was after it became cool enough for protons and electrons to combine into atoms. This is referred to as "recombination."

Free charged particles interact with most any photons they encounter; atoms, like hydrogen in this example, only absorb and emit photons with certain energies. As a result of this, before recombination, the universe was opaque, and after it it's transparent. From the wavelengths the neutral hydrogen absorbs, it is possible to obtain its concentration, thus telling us how much hydrogen there was just after recombination, using the light from the CMB. That's how we know the hydrogen content of the universe at early times.

By now, of course, the expansion of the universe since early times has stretched the wavelengths.
[contd]

Mar 12, 2019
[contd]
But the spectra of hydrogen atoms are still there; hard to detect, but present. The other thing to keep in mind is that because of redshifting, these microwaves stopped interacting with hydrogen still in early times. So the amount of hydrogen is "imprinted" on the CMB, and can't be changed by hydrogen in later times.

Now for your question on antimatter time reversal.

This is a very hard problem in physics; this is because the formalism, the Hermetian Hamiltonian, of quantum field theory automatically assumes time going forward and has no mechanism for calculating interactions in backward time.

You should not assume that this means that causality for antimatter is reversed; in particular, it does not mean that particles show the opposite of the 2LOT.

Some of what I've said here is handwaving; the fact is, although we know that CPT symmetry is never broken, we still don't know exactly what it means to say antiparticles "move backward in time."
[contd]

Mar 12, 2019
[contd]
It is of some interest that the Fluctuation Theorem (FT) indicates that the 2LOT applies less and less below a certain size limit; it can be violated for short times and small expanses, and the shorter the time and the smaller the volume, the more likely it is to be 50/50 with anti-entropic action as well as entropic. The laws of quantum mechanics do not necessarily conform to the laws of classical mechanics, and this appears to be one of the places this is true. So don't expect antimatter to be reversing entropy except on an individual particle basis. It won't.

As we continue research in this area, we can expect to get more information; but right now, you will find that it's complex and there is no consensus on exactly what it means at the classical or macroscopic scale.

Mar 12, 2019
It is of some interest that the Fluctuation Theorem (FT) indicates that the 2LOT applies less and less below a certain size limit; it can be violated for short times and small expanses, and the shorter the time and the smaller the volume, the more likely it is to be 50/50 with anti-entropic action as well as entropic. The laws of quantum mechanics do not necessarily conform to the laws of classical mechanics, and this appears to be one of the places this is true. So don't expect antimatter to be reversing entropy except on an individual particle basis. It won't.
............100% Pop-Cosmology psycho-babble. If you tried verbally repeating what you just wrote as quoted, you'd be lost for words before you got to the first comma.

Mar 12, 2019
That ain't cosmology, @Benni. You're lying again.

Mar 12, 2019
(My link to this web site is getting flaky. Hope that I don't get annihilated!)

The CMB is what I was referring to as the BR. I understand it is all microwave now, but as you say, it is all shifted due to expansion. Perhaps I read some bogus information. It referenced this as once being composed of many forms of radiation up to gamma.

Maybe I assumed the original wavelengths could be sorted out just like a highly red-shifted galaxy, but not that this could provide accurate details of sequential events, to say nothing of amounts of various "particles". That was the basis for my skeptical position on deriving absolutes from it. It looks like such a mess.

cont.

Mar 12, 2019
cont.

I am certainly aware of absorption-emission having done quite a bit of spectroscopy. But did not study most of this cosmic stuff until recently, so it all seems rather opaque to me! And despite your professional attempts to clarify things, I will need to do a lot more reading to buy into this stuff. The devil is always in the details.

And I don't expect antimatter to be reversing entropy, period. Just like it does not have anti-gravity, and anti- other things.

Finally, I am delighted to read that "there is no consensus on exactly what it means." That in itself says a lot!

Are you a professor of physics?

Mar 12, 2019
Remember that because of redshift, later times cannot change the spectra from earlier times, because the earlier time spectra can no longer interact with later time matter.

Mar 12, 2019
Are you a professor of physics?


Da Schneibo is a retired computer programmer. His retirement career mostly involves being an embedded Physorg Moderator which is why you see his presence in this chatroom so much, he lives here to keep from dying of boredom & gives most of the rest of us giggle fits because he is so corny with his ideas.

He's a big fan of 19th Century Cosmology Black Hole TUGMath, concocted in that century by the same individuals who concocted Aether Theory. He does not believe black holes have a singularity, a resulting consequence of his acceptance of 19th Century Black Hole TUGMath theory.


Mar 12, 2019
What is the predicted time limit for absorption by hydrogen, helium and/or lithium?

Mar 12, 2019
I don't know; it can be calculated. It's almost certainly less than a billion years, if I were to estimate. That one you'll have to ask someone who's interested enough to run the numbers.

Bear in mind that these are specific frequencies determined by the geometry of electron orbitals. They're extremely precise; they're the basis for atomic clocks.

Mar 12, 2019
Are you a professor of physics?


Da Schneibo is a retired computer programmer. His retirement career mostly involves being an embedded Physorg Moderator which is why you see his presence in this chatroom so much, he lives here to keep from dying of boredom & gives most of the rest of us giggle fits because he is so corny with his ideas.

He's a big fan of 19th Century Cosmology Black Hole TUGMath, concocted in that century by the same individuals who concocted Aether Theory. He does not believe black holes have a singularity, a resulting consequence of his acceptance of 19th Century Black Hole TUGMath theory.



Go away you cretin. They are talking science here. This stuff is well beyond fools like you.

Mar 12, 2019
Yes, "specific frequencies determined by the geometry of electron orbitals" is standard physical chemistry. I am surprised that it would be a billion years. I would expect it to be much shorter.

More interested in how the complex CMB has been "de-convoluted" to reveal some of its secrets. What wiki link might you suggest for this?


Mar 12, 2019
I think it was much shorter too, but since I don't care that much, I didn't run the numbers; I made an estimate and padded it plenty. If I get interested enough I might take the trouble, but it's a complex calculation and I just don't care enough.

There isn't any need to "de-convolve" the CMB; it's been done. You're not going to find a Wikipedia link; if you're lucky you'll contact an astrophysicist who cares enough to draw out the calculations for you, but they're generally too busy.

Mar 12, 2019
Nurse...NURSE!!
Da Schitts is talking to his sock puppets again.

Mar 12, 2019
these are specific frequencies determined by the geometry of electron orbitals.
......and schniebo changes his mind again.Last week electrons were not orbitals, they were just quantum blobs that just sort of wander around doing nothing special.

Mar 12, 2019
Will have to investigate by other means. This seems to be the most important aspect of understanding what happened way back when. If there is an error in these calculation, or even one erroneous assumption, it could throw things off a tad.

Have seen such errors so many times that I simply assume they are there until demonstrated otherwise, and this is the biggest "place" for such things to occur. As you said, there is no consensus. Such comments always get my mind working OT. Now I have to chase this down.

I suspect we will meet again on another thread. Thanks for all your input.

Cheers!

Mar 12, 2019
@Da Schreib
@dfjohnsonphd.

I note obsolete BB-related assertions/claims creeping into your discussion:

1) @Da Schneib's continuing belief that the observed CMB is:
residual radiation from the Big Bang
has already been falsified by me; pls see my relevant posts (starting on Jan 30, 2019) re ON-GOING sources/processes for the CMB, in thread:
https://phys.org/...html#jCp

2) I also have long pointed out that all BB-dependent nucleosynthesis/elemental 'source/abundance estimates' are misleading; as universal process recycles material all the time, sending out 'deconstructed' matter/energy (protons, electrons etc) into deep space between galaxies/clusters, so producing an ONGOING EQUILIBRIUM of 'elemental abundances' that cannot be attributed to 'primordial' status as claimed by BB proponents; pls see my posts re deconstruction/recycling etc in thread:https://phys.org/...ies.html

Cheers. :)

Mar 12, 2019
ps:
@Da Schneib and @dfjohnsonphd.

3) @dfjohnsonphd, I also noted the following from @Da Schneib to you:
Remember that because of redshift, later times cannot change the spectra from earlier times, because the earlier time spectra can no longer interact with later time matter.
Which is obviously illogical assertion/claim; since IF that were so, we would never have been able to detect these NOW with our material telescopes/instruments.

Beware of obsolete BB-biased 'memes' which have long since been busted. Cheers. :)

Mar 13, 2019
Last week electrons were not orbitals,
They aren't this week either. You're lying again, @Benni. Orbitals are 3D regions in space that electrons are found in around atoms. They aren't orbits. And electrons aren't orbitals; orbitals are 3D regions in space. Electrons are particles.

they were just quantum blobs that just sort of wander around doing nothing special.
Lying again, @Benni. Show where I said any of this. If you can't it's obvious you're lying again, just like you always do.

Mar 13, 2019
Me again, Da Schneib.

Looking up CMB on wiki, I see that from spectral radiance, photon peak energy can be calculated two different ways, by wavelength or by frequency. There appears to be about a significant variance when using the two different methods. What does this mean? I would have thought only one answer for this.

Hope you are still reading this.


Mar 13, 2019
Yes, I am.

Frequency and wavelength are complementary; specifically, they vary inversely. Can you please tell me what in the Wikipedia article you are claiming these two are making different claims about? That can't be right.

Mar 13, 2019
The specific data I am referring to is below (a direct cut from Wiki's CMB:

"Precise measurements of the CMB are critical to cosmology, since any proposed model of the universe must explain this radiation......The spectral radiance dEν/dν peaks at 160.23 GHz, in the microwave range of frequencies, corresponding to a photon energy of about 6.626 × 10−4 eV. Alternatively, if spectral radiance is defined as dEλ/dλ, then the peak wavelength is 1.063 mm (282 GHz, 1.168 x 10−3 eV photons)."

end quote

Mar 13, 2019
As we know, and you noted, frequency and wavelength are complementary.

I was expecting only one answer to this issue, but then thought again based on what these "answers" are all about........

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