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Old 5th November 2017, 12:02 PM   #1
Ron_Tomkins
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Michio Kaku: We shouldn't even exist cuz no antimatter

Ok, so I just watched a short interview where Michio Kaku says that according to new findings, there's no reason the Universe should exist because we find that there's an immense abundance of matter, and yet, no antimatter to go with it.

Here's the interview
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I AGREE


Now, aside from the interviewer being extremely cringe-worthy in her stupid way to conduct the interview (By playing the ol' "ohh I don't understand anything you're saying cuz I'm so dumb hahaha but keep talking cuz this is fascinating"), what bothers me the most is that she didn't ask a crucial question which I think, any layman such as myself, would begin by asking:

How do you know there is no antimatter out there to balance out the matter we have?

I mean, after all, the Universe is like.... really big, right? We probably haven't even looked at a quarter of the amount of Universe there is. So why are we immediately assuming that there's no antimatter out there? There could totally be any infinite amounts of antimatter somewhere in the vastness of the cosmos. And yet, Kaku seems to talk about the issue as if he had already looked into every corner of the universe.

So that's my question regarding this issue. If any science-savys out there can begin to answer that, I would appreciate it.
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Old 5th November 2017, 01:06 PM   #2
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New, hyper-accurate measurements have shown that (apart from the symmetry), there is no discernible difference between matter particles and their anti-matter counterparts.
Most theories about the creation of the universe suppose an imbalance between the two types caused a surplus of matter over antimatter - but that would require that something makes them behave in a-symmetrical ways.
To the very, VERY best of data we can currently obtain we cannot find any difference that would suggests such a break of symmetry.
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Old 5th November 2017, 01:28 PM   #3
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When matter and anti-matter come into contact photons are released in large abundance, and scientists know what this should look like. If there were an area of the Universe that was mostly anti-matter there would be some places where it bordered matter dominated space, even at really low densities.

So unless there are really really low density voids between all matter dominated and anti-matter dominated portions of the Universe, scientists should be able to see signals from matter-antimatter annihilation when looking at the sky. But they don't, so while the amount of matter in the Universe should theoretically equal the amount of anti-matter, instead the data shows that the amount of anti-matter in the Universe might as well be zero compared to the amount of matter.

Of course this is why I hate "news" like this. It isn't that the Universe shouldn't exist, it is just that our models that tell us there should be equal amounts of matter and anti-matter in the Universe are wrong in some way we don't understand yet.
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Old 5th November 2017, 01:28 PM   #4
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Actually I believe that it is possible to convert energy into matter without created antimatter. As a result there is matter, but only very tiny amounts of antimatter in the universe. The later is destroyed very soon after it is created.

Cannot watch the video as it is not available in my country. I would not take the video very seriously as it is not even a science channel.
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Old 5th November 2017, 01:36 PM   #5
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This is Neil deGrasse Tyson tier science. What he means is a banal scientific situation where the current model doesn't match observations. But of course he has to sex it up for the "I *********** love science" audience.
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Old 5th November 2017, 04:20 PM   #6
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Originally Posted by theprestige View Post
This is Neil deGrasse Tyson tier science. What he means is a banal scientific situation where the current model doesn't match observations. But of course he has to sex it up for the "I *********** love science" audience.

Seems to me the universe does exist. If there is no anti-matter, then anti-M is not a necessity. Time to come up with a new model that does match observation.

It's called "science".

"I *********** love science".
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Old 5th November 2017, 04:46 PM   #7
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Crazy question: Is there any possibility of a mechanism that, at the time of the Big Bang, sent most of what we consider antimatter in a different "direction" that is not within the universe we know. Perhaps a different direction in time, or into dimensions we can't interact with? Probably doesn't make any sense, but I'd just like someone to explain why, because this stuff is way above me.
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Old 5th November 2017, 05:32 PM   #8
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Originally Posted by Ron_Tomkins View Post
How do you know there is no antimatter out there to balance out the matter we have?
Basically because of the principle that we are not on a special place in the universe. This is the Copernican principle. The observable universe is assumed to be representative of the universe as a whole unless there is evidence otherwise. We see that the observable universe does not contain equal amounts of matter and antimatter and thus there is no reason to think that the entire universe does.
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Old 5th November 2017, 05:47 PM   #9
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Psst

opens trenchcoat

Want to buy some antimatter?
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Old 5th November 2017, 06:13 PM   #10
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Originally Posted by The Great Zaganza View Post
New, hyper-accurate measurements have shown that (apart from the symmetry), there is no discernible difference between matter particles and their anti-matter counterparts.
Most theories about the creation of the universe suppose an imbalance between the two types caused a surplus of matter over antimatter - but that would require that something makes them behave in a-symmetrical ways.
To the very, VERY best of data we can currently obtain we cannot find any difference that would suggests such a break of symmetry.
CP violations have been found. There are known differences in the decay of matter and anti-matter particles.

There are three conditions necessary for the abundance of matter over anti-matter (or vice versa):

https://en.wikipedia.org/wiki/Baryog...rov_conditions
Quote:
In 1967, Andrei Sakharov proposed a set of three necessary conditions that a baryon-generating interaction must satisfy to produce matter and antimatter at different rates. These conditions were inspired by the recent discoveries of the cosmic background radiation and CP-violation in the neutral kaon system. The three necessary "Sakharov conditions" are:

Baryon number B violation.
C-symmetry and CP-symmetry violation.
Interactions out of thermal equilibrium.
ETA I think the issue raised in the video is that we need an asymmetry between protons and anti-protons such that they could have been created at different rates, and that asymmetry hasn't been found. It's one thing to have symmetry violations in some particular anti-matter particles, that's a sort of proof of principle, but the actual question of the imbalance of matter vs. antimatter has to do with protons (obviously the same issue for electrons). But considering that we haven't even been able to put anything except a lower bound on the decay rate of protons, that's not that surprising. The conditions in the early universe were just very different from what they are now, so it's hard to do experiments that give insight into those conditions.
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Old 6th November 2017, 06:19 AM   #11
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Originally Posted by rjh01 View Post
Actually I believe that it is possible to convert energy into matter without created antimatter. As a result there is matter, but only very tiny amounts of antimatter in the universe. The later is destroyed very soon after it is created.
Not without breaking conservation laws, which as far as scientists can tell, are absolute. For instance, electrical charge must be conserved. If you start off with 0 charge, and you want to produce an electron with a charge of -1, you have to produce a positron with a charge of +1 to keep the total charge at 0.
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Old 6th November 2017, 07:17 AM   #12
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Originally Posted by Fizil View Post
Not without breaking conservation laws, which as far as scientists can tell, are absolute. For instance, electrical charge must be conserved. If you start off with 0 charge, and you want to produce an electron with a charge of -1, you have to produce a positron with a charge of +1 to keep the total charge at 0.
Just to make a point: if you had a series of decays that resulted in a proton and an electron being produced you'd still have charge conservation.

Charge conjugation symmetry isn't an actual symmetry of nature. https://en.wikipedia.org/wiki/CP_violation

That said CP violations are pretty rare. But as I said, if the Sakharov conditions are met, then you can have an imbalance in matter/anti-matter. There's nothing we know that explicitly contradicts any of the Sakharov conditions.
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Old 6th November 2017, 08:29 AM   #13
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does any of it really anti-matter?
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Old 6th November 2017, 08:50 AM   #14
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Originally Posted by Reality Check View Post
We see that the observable universe does not contain equal amounts of matter and antimatter and thus there is no reason to think that the entire universe does.
But it seems to me that there is also no reason to think that the entire universe doesn't, since we can't observe it. How can we assume anything about a great portion of the universe we can't even see?
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Old 6th November 2017, 09:01 AM   #15
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Originally Posted by Ron_Tomkins View Post
But it seems to me that there is also no reason to think that the entire universe doesn't, since we can't observe it. How can we assume anything about a great portion of the universe we can't even see?
I actually don't think anyone has much to say about the anti-matter content of areas very far outside of the observable universe.

On the other hand if you are talking about regions not particularly far outside of the observable universe it would be weird if things suddenly started getting different there. There's nothing special about our particular region so why would it be that a region centered on us is all matter but one centered on a galaxy 5 billion lightyears from us has anti-matter in it?

Anyway, the way we know that there are no anti-matter galaxies out there is that there is enough interaction between galaxies and enough stuff between galaxies that we'd see gamma rays being given off when matter dominated regions interacted with anti-matter dominated regions.

It also doesn't really solve the problem: If matter and anti-matter are created in the same proportion how do you manage to separate them out into different galaxies?
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Old 6th November 2017, 09:15 AM   #16
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Originally Posted by Ron_Tomkins View Post
But it seems to me that there is also no reason to think that the entire universe doesn't, since we can't observe it. How can we assume anything about a great portion of the universe we can't even see?
Within the observable universe, there doesn't appear to be any significant portion of antimatter. Even the interstellar medium isn't empty. If there were a large boundary of antimatter, we would expect to see the signature of its interaction with matter. That signature has not been detected.

Certainly there could be regions of antimatter beyond the horizon of the visible universe, but then we don't really have any explanation for how there's a fundamental difference on such large scales.

Yes, there could be large amounts of antimatter somewhere we can't see it, but there's nowhere it could be and still be a good fit for existing models.
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Old 6th November 2017, 09:15 AM   #17
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Originally Posted by Roboramma View Post
Just to make a point: if you had a series of decays that resulted in a proton and an electron being produced you'd still have charge conservation.

Charge conjugation symmetry isn't an actual symmetry of nature. https://en.wikipedia.org/wiki/CP_violation

That said CP violations are pretty rare. But as I said, if the Sakharov conditions are met, then you can have an imbalance in matter/anti-matter. There's nothing we know that explicitly contradicts any of the Sakharov conditions.
But wouldn't a reaction producing electron + proton violate conservation of lepton number and baryon number unless the original system contained a net 1 lepton, and a net 3 quarks?

I believe CP violation is different from the conservation laws I am talking about. As far as I know, in experimental examples of CP violation, you have a composite hadron consisting of a certain flavour of quark, and a certain flavour of anti-quark. These can transform by basically switching "anti-ness": so for instance if you had particle consisting of Up/Anti-Bottom, it can change to Anti-Up/Bottom, and vice versa. CP violation comes from the fact that these processes are more likely to occur in one direction than the other. No conservation law is violated here, the CP violation comes from the fact that we observe that certain reactions are more likely to occur than others, while if CP symmetry weren't broken we should expect them to happen equally often.

CP violation is probably the explanation for the predominance of matter over anti-matter in the universe. The current experimentally verified examples of CP violation can't account for it though. My understanding is that the hope is that experiments hoping to show CP violation in leptons is the main hope for making up the difference needed to account for the predominance of matter that we see.

Or everything I just said could be wrong. I am merely a physics enthusiast, not a qualified physicist myself. I would be interested to see a worked out example of how you might generate an electron and proton from say an arbitrarily high energy photon if anyone has that level of physics chops. Presumably lepton number could be conserved through the production of an anti-neutrino, but I must admit I'm baffled at how you can get a proton out without generating an additional 3-quark hadron consisting of anti-quarks to conserve baryon number.
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Old 6th November 2017, 09:24 AM   #18
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Originally Posted by shemp View Post
Crazy question: Is there any possibility of a mechanism that, at the time of the Big Bang, sent most of what we consider antimatter in a different "direction" that is not within the universe we know. Perhaps a different direction in time, or into dimensions we can't interact with? Probably doesn't make any sense, but I'd just like someone to explain why, because this stuff is way above me.
Given the BBT, the universe was very small during certain time, now when the universe became cool enough for the matter and anti-matter to fall out it was much larger.
I think the issue is that unless all the matter is on the other side of the observable universe, we would see the area where the two types interact.
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Old 6th November 2017, 09:30 AM   #19
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Well, violation of conservation of baryon number is one of the Sakharov conditions, so yeah, you are right there. And all experiments have been consistent with baryon number being conserved, but that doesn't mean it's actually conserved.

I'm no expert either, I just happened to have watched this lecture last week:
https://www.youtube.com/watch?v=gdFldkitkJA

Which goes into all this stuff pretty well. My understanding is that the specifics aren't known but there's nothing about baryogenesis that contradicts what is known.
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Old 6th November 2017, 10:35 AM   #20
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Originally Posted by Roboramma View Post
Well, violation of conservation of baryon number is one of the Sakharov conditions, so yeah, you are right there. And all experiments have been consistent with baryon number being conserved, but that doesn't mean it's actually conserved.

I'm no expert either, I just happened to have watched this lecture last week:
https://www.youtube.com/watch?v=gdFldkitkJA

Which goes into all this stuff pretty well. My understanding is that the specifics aren't known but there's nothing about baryogenesis that contradicts what is known.
Thanks for the link. I love Susskind's Stanford lectures, but hadn't gotten around to his Cosmology lectures yet.
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Old 6th November 2017, 11:03 AM   #21
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Mr. Kaku is wrong. Proof of an alternate universe was documented in the late 60's.

Captain James T. Kirk: [narrating] Captain's log, stardate unknown. We are trapped in a savage parallel universe from which we must escape within four hours, or I will face a death sentence at Mr. Spock's hands.
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Old 6th November 2017, 12:49 PM   #22
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Originally Posted by Ron_Tomkins View Post
But it seems to me that there is also no reason to think that the entire universe doesn't, since we can't observe it. How can we assume anything about a great portion of the universe we can't even see?
What we cannot observe is speculation not science which is based on observation. We could speculate that the non-observable universe is made of pink candy floss () and have almost as good a chance of being right as speculating that it is made large amounts of antimatter.

As I wrote, a reasonable assumption called the Copernican principle is that the universe is not special where we are.
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Old 7th November 2017, 08:39 AM   #23
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In my own thinking, without some disparity between matter/antimatter, living in a universe with matter instead of nothing is like living in a positively charged universe. It would tell you that something is very wrong.
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Old 7th November 2017, 09:50 AM   #24
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So, in short: Even though we cannot see all of the Universe, we should expect to see some sort of "visual cue" within the observable Universe, that indicates that somewhere out there, there are some matter-antimatter collisions occurring out there. Right?

In other words, it isn't possible at all that such collisions are occurring within some parameter where we just cannot have any sort of visual access, and so, we can't tell for certain whether these collisions are actually happening, correct?
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Old 7th November 2017, 10:06 AM   #25
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Even if there were anti-matter out there somewhere where we haven't looked to balance out the matter that exists it wouldn't solve the problem. It would just raise another issue: why is the anti-matter separated from the matter in a big clump like that?

There's no known force that would make that happen. Conservation laws, as far as I know, are all local. It's not just that charge is conserved, it's conserved locally.

So you've got an ultra dense, ultra hot, sea of photons. After some collisions proton-anti-proton pairs are produced. But somehow all the anti-protons migrate off into one region and the protons into another? That would be weird.
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Old 7th November 2017, 01:37 PM   #26
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Originally Posted by Roboramma View Post
Even if there were anti-matter out there somewhere where we haven't looked to balance out the matter that exists it wouldn't solve the problem. It would just raise another issue: why is the anti-matter separated from the matter in a big clump like that?

There's no known force that would make that happen. Conservation laws, as far as I know, are all local. It's not just that charge is conserved, it's conserved locally.

So you've got an ultra dense, ultra hot, sea of photons. After some collisions proton-anti-proton pairs are produced. But somehow all the anti-protons migrate off into one region and the protons into another? That would be weird.
Ah, well, that is interesting as well. See? Another thing that should have been addressed at the interview but wasn't, cause the idiot host is too stupid to know how to ask the right questions.
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Old 7th November 2017, 02:04 PM   #27
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Originally Posted by Ron_Tomkins View Post
So, in short: Even though we cannot see all of the Universe, we should expect to see some sort of "visual cue" within the observable Universe, that indicates that somewhere out there, there are some matter-antimatter collisions occurring out there. Right?
In short: the wrong way around.
These hypothetical "visual cues" would be observations and so have to be part of the observable universe. We have observed that there is no large scale (e.g. gas, planets, stars, galaxies) matter-antimatter collisions in the observable universe. That is the "visual cue" that the entire universe has no antimatter.
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Old 7th November 2017, 02:26 PM   #28
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My theory is that the entire universe is antimatter except for the Milky Way, and that when the Andromeda Galaxy arrives we're gonna have a bad time.
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Old 7th November 2017, 02:27 PM   #29
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Another example of fine-tuning:

"Somewhere hidden in the physics of protons there must be a slight asymmetry that resulted in protons outnumbering antiprotons by one in a billion.

But why does our universe possess a perfect symmetry with respect to charge but a slight asymmetry with respect to matter and antimatter? Nobody knows! If the situation was reversed and our universe was born with zero protons, but with a net excess of charge, the immense repulsive action of the electromagnetic force would prevent matter present from collapsing into anything resembling stars and galaxies.

No matter which way we turn, the properties of our universe have finely tuned values that allow us to be here. Deviate ever so slightly from them and the universe would be sterile – or it may never have existed at all. What explanation can there be for this fine-tuning?
"

To some, the picture of the multiverse is comforting, naturally explaining the puzzle of our own fine-tuning. But at present, we have no idea whether this immense sea of universes exists, and they may always be beyond the reach of experiment and observation; if this is the case, is the multiverse more philosophical musing than robust science?
https://cosmosmagazine.com/physics/a...uning-and-life
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Old 7th November 2017, 03:56 PM   #30
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Victor Stenger had some nice comments on fine tuning
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Old 7th November 2017, 05:20 PM   #31
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Originally Posted by Reality Check View Post
As I wrote, a reasonable assumption called the Copernican principle is that the universe is not special where we are.
There's even a movie about that principle, which suckered Dr Kaku into making an appearance. He has a bit of history of being less than careful about what he says and to whom.
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Old 8th November 2017, 07:07 PM   #32
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Originally Posted by Fizil View Post
Thanks for the link. I love Susskind's Stanford lectures, but hadn't gotten around to his Cosmology lectures yet.
Yeah I'm a huge fan of his. The Cosmology series is great.
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Old 8th November 2017, 10:50 PM   #33
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The other thing that bothers me is the whole "The Universe shouldn't exist" phrase. First of all, that gives all the religious people and the woos the feeling that they are right, because science is basically "admitting" that there has to be "something else" outside of the realm of science, to explain why we are here, etc etc.

Second, the phrase doesn't accomplish anything. It's like when something bad/amazing happens to you and you say "This shouldn't be happening right now". Well.... it is. So what are you gonna do about it? Being in denial about the fact that it's happening, doesn't advance any future actions to figure out the solution (I'm not saying this is literally the case with the scientists who made this recent discovery. This is more about how to present the problem to the public)

The conclusion shouldn't be "According to this new finding, the Universe shouldn't exist", but rather something like "According to this new finding, our calculations of how the Universe came to be, are missing one piece of the puzzle" or something in that line. And that opens a whole set of questions. Chiefly, where the "missing piece" or "error in calculation" is happening. It could mean, for instance, that the theory of Big Bang is wrong, or has a fatal mistake of calculation. Who knows? Either way, this shouldn't be anything new, since science is constantly correcting and updating itself.


On a side note, and this is probably a stupid question but, what about Dark Matter? Could this immense amount of "stuff we don't even know what is, and which conforms a great percentage of the Cosmos" be an immediate suspect regarding the whole "Where's the missing antimatter" question?
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Old 8th November 2017, 11:23 PM   #34
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Originally Posted by Ron_Tomkins View Post
The other thing that bothers me is the whole "The Universe shouldn't exist" phrase. First of all, that gives all the religious people and the woos the feeling that they are right, because science is basically "admitting" that there has to be "something else" outside of the realm of science, to explain why we are here, etc etc.
I agree. I think that the charitable reading is that he's saying that experimental results (the new measurement from CERN, I guess) are inconsistent with theories of baryogenesis. Of course, that's not even true, it's just getting harder to see where the CP violation that could have led to baryogensis happened.

Here's the thing though, while this isn't a very elegant solution, we are always left with the possibly that the universe just started out with more matter than anti-matter. If the Sakharov conditions aren't met, that just means that when you produce new matter you necessarily produce new anti-matter. That doesn't mean that the total matter - the total anti-matter must sum to zero. It just means that sum can't change. But if it started at some non-zero value, then you'd still have that same non-zero value today.

It's not very elegant because it's just another number we have to throw into the theory, and physicists would certainly rather find a theory that can explain the discrepancy, but it's always possible that the universe just happens to be this way.

Quote:
On a side note, and this is probably a stupid question but, what about Dark Matter? Could this immense amount of "stuff we don't even know what is, and which conforms a great percentage of the Cosmos" be an immediate suspect regarding the whole "Where's the missing antimatter" question?
No. There is specifically a discrepancy in the number of electrons vs. positrons, the number of protons vs. anti-protons. The dark matter is not made of either positrons or anti-protons or both. If it were it wouldn't be dark (anti-protons have electric charge and thus interact with electromagnetism, ie. light).

Anti-matter behaves basically exactly like matter. If collections of matter form into stars and galaxies collections of anti-matter would also form into stars and galaxies. CP violations aside, they will exhibit all the same dynamics.

Which might make you ask again how we know that some other galaxy isn't made of anti-matter? The main reason is that galaxies interact. Sometimes they collide, and there is material between the galaxies. If there were a galaxy of anti-matter it's edges would be interacting with that intergalactic stuff (hydrogen, dust, etc.). When anti-matter and matter interact they annihilate and give off gamma rays (very high energy light). We'd see that. We don't, so no anti-matter galaxies.
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Old 9th November 2017, 06:55 AM   #35
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As Roborama says.... This is pretty much what DeGrass Tyson was saying in a lecture I listened to recently.
That the initial precipitation of matter from the raw energy of the Singularity had a slight preponderance of matter, and that after all the antimatter-matter annihilation was done, we see what’s left.
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Old 9th November 2017, 08:28 AM   #36
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Originally Posted by Bikewer View Post
As Roborama says.... This is pretty much what DeGrass Tyson was saying in a lecture I listened to recently.
That the initial precipitation of matter from the raw energy of the Singularity had a slight preponderance of matter, and that after all the antimatter-matter annihilation was done, we see what’s left.
Well, as I said that's certainly a possibility.

In the lecture by Susskind that I linked above what he says, at least as far as I understand it, is different. And I think it's the basic idea that they were testing in the experiment that Michio Kaku is talking about in the OP video.

So, what's the idea? You start off with a sea of photons which produce proton/anti-proton pairs through collisions (this is an extremely high energy environment where this can happen). So at this point you have the same amount of matter as anti-matter. But there is an assymetry in the decay rate of protons and anti-protons. So more anti-protons decay than protons. Meanwhile for some, very short, period of time the annihilation of proton/anti-proton pairs is balanced by their production from photon collisions. But then as the universe expands it cools and the average collision no longer has enough energy to produce proton/anti-proton pairs. So it starts to be dominated by annihilation instead. After some time all of the remaining anti-protons have annhilated with protons. But there are fewer of them than protons now because more of them decayed. So you are left with some protons.

How many protons are left? That depends on the decay rate of anti-protons. But from observation it's about 1/108.

Now, you might say "wait a minute, the time scales involved are extremely short and we know that anti-protons are stable for much longer time periods". That's true, but they are stable in the low temperate environment of the modern universe, and the idea is that both protons and anti-protons would have a much higher decay rate in the high energy environment of the very early universe.

Of course we don't even know if protons decay at all, so this is all theoretical. The idea of the experiment mentioned by Kaku seems to be that the asymmetry between protons and anti-protons that leads to different decay rates should also present itself in some other properties. So they were looking for differences in... I forget, the magnetic moment? Something like that.
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Old 9th November 2017, 08:53 AM   #37
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Originally Posted by Roboramma View Post
I agree. I think that the charitable reading is that he's saying that experimental results (the new measurement from CERN, I guess) are inconsistent with theories of baryogenesis. Of course, that's not even true, it's just getting harder to see where the CP violation that could have led to baryogensis happened.

Here's the thing though, while this isn't a very elegant solution, we are always left with the possibly that the universe just started out with more matter than anti-matter. If the Sakharov conditions aren't met, that just means that when you produce new matter you necessarily produce new anti-matter. That doesn't mean that the total matter - the total anti-matter must sum to zero. It just means that sum can't change. But if it started at some non-zero value, then you'd still have that same non-zero value today.

It's not very elegant because it's just another number we have to throw into the theory, and physicists would certainly rather find a theory that can explain the discrepancy, but it's always possible that the universe just happens to be this way.



No. There is specifically a discrepancy in the number of electrons vs. positrons, the number of protons vs. anti-protons. The dark matter is not made of either positrons or anti-protons or both. If it were it wouldn't be dark (anti-protons have electric charge and thus interact with electromagnetism, ie. light).

Anti-matter behaves basically exactly like matter. If collections of matter form into stars and galaxies collections of anti-matter would also form into stars and galaxies. CP violations aside, they will exhibit all the same dynamics.

Which might make you ask again how we know that some other galaxy isn't made of anti-matter? The main reason is that galaxies interact. Sometimes they collide, and there is material between the galaxies. If there were a galaxy of anti-matter it's edges would be interacting with that intergalactic stuff (hydrogen, dust, etc.). When anti-matter and matter interact they annihilate and give off gamma rays (very high energy light). We'd see that. We don't, so no anti-matter galaxies.
I feel proud to have understood (or at least I think I understood) most of that. Thanks
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Old 10th November 2017, 02:52 PM   #38
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Originally Posted by Roboramma View Post

Anti-matter behaves basically exactly like matter. If collections of matter form into stars and galaxies collections of anti-matter would also form into stars and galaxies. CP violations aside, they will exhibit all the same dynamics.
We don't actually know this though, do we? I know humans have produced antihydrogen and it seems to exhibit the same behavior as hydrogen, but I don't think anyone has any clue about more complex arrangements of antimatter or what large scale clumping might mean. I think at this point, your statement would be an assumption based on limited knowledge. Well grounded knowledge, but limited. Correct me if I'm wrong.
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Old 10th November 2017, 10:17 PM   #39
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Originally Posted by Crawtator View Post
We don't actually know this though, do we? I know humans have produced antihydrogen and it seems to exhibit the same behavior as hydrogen, but I don't think anyone has any clue about more complex arrangements of antimatter or what large scale clumping might mean. I think at this point, your statement would be an assumption based on limited knowledge. Well grounded knowledge, but limited. Correct me if I'm wrong.
Well, we know the mass, charge, etc. of each anti-particle. Everything relevant to forming stars, planets, and galaxies is the same. And while there are violations to CP symmetry, CPT really is a symmetry of nature. T is time reversal symmetry, so what that means is that if you take an anti-matter system and switch it with an identical matter system and reverse left for right and run it backwards in time, you will get the same results.

That doesn’t leave much room for large scale differences in dynamics.
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Old 11th November 2017, 04:45 AM   #40
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Not that I know much about it but have a question, is it known what stage or epoch particle-anti particle annihilation could occur? As in would it (or not) occur in the quark epoch, would it occur at the very moment of the big bang, is there any time it wouldn't have occurred but then a condition reached in the universe that did allow it?
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