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RE: Dark stars as a cosmic window on a mirror world
Stupid question: Is there a second copy of us in the mirror world based on other physical laws???
Stupid question: Is there a second copy of us in the mirror world based on other physical laws???
Ahaha! The question is not stupid at all. And I don't know the answer with 100% certainty..
The answer is however probably no, as the mirror world chemical elements are not occurring in the same proportion as in the visible world. For instance, the mirror world has much more helium than what is going on in our visible world. See here (if you have the strength to read it ;) ). Therefore, we may expect things to be entirely different.
Also note that gravity is the same in both worlds.
As usual, the questions (and answers) are illuminating.
Lol!
"Illuminating" is definitely the appropriate word when talking about photons and dark photons! I don't know whether this was on purpose, but this made my day (who started very badly with a lot of train issues).
I'm not so clever as to make such a witty comment:) But I do have a question about photons. This may reveal (will reveal) my ignorance, but I keep going back to the same place in your piece with the same question:
Why do usual and dark photons mix? I understand how conversion may take place once they have met, but how and why do these elements from mirror worlds mix in the first place?
Thank you in advance and apologizing for asking what may have an obvious answer...
The short answer is: symmetries! I am however sure you are looking for something longer. So here it is. I will try to make it reasonably understandable. Let’s hope it works, because it is not trivial at all, at least for non particle physicists (so that you can already conclude that your question is by far not an easy one).
In the context of particle physics, we first start by postulating a few symmetries that will dictate how the fundamental interactions work. In the case of the model under consideration in this post, we thus have 6 symmetries in total: one for electromagnetism, one for the weak and one for the strong interactions, plus the three mirror counterparts.
The symmetries related to the two electromagnetisms are special: there are such that photon self-interactions must be forbidden (to match data). And of course, the same holds for the mirror counterpart by virtue of the definition of the mirror world.
From there, we can build the theory: anything that is allowed by the symmetries has to be there (and is actually predicted). The symmetries related to the dark/visible electromagnetisms allow the two photons to mix when they propagate. This can be seen as a dark photon turning into a visible one when it propagates, or vice versa. Another way to see this is as follows: mirror matter interacts with the dark photon only. However, since the dark photon can turn into a visible photon, mirror matter somehow also interact with the visible photon (though mixing, the interaction being somehow not direct). And again, the same holds for visible matter and the dark photon.
However, electromagnetism is known for more than a century. And very well known. Therefore, if visible photons could turn into dark photons, we should have already noticed something weird in data. And we haven’t. As a result, the mixing between the two photons is constrained to be of at most one part in a billion. It is thus damned small, so that any related phenomenon will be super rare, and thus hard to detect experimentally.
I hope this satisfies your curiosity! In any case, feel free to come back to me for more information or further clarifications.
That was a wonderful answer! I do believe I understand:
In theoretical particle physics, you follow the laws, and the laws allow this...predict this. However,
I had to read it a couple of times...not because the answer was dense but because, I had to :) But I believe I've got it. A very tiny, but satisfying moment of enlightenment :))
Thank you, @lemouth!
Concerning the mixing, it cannot be zero. A zero means simply there must be a symmetry behind it. But data is the queen after all. So if data tells it's small, it's small.
One further question (without any real answer) which this could lead to is the following: How come it is so small? This is indeed very unnatural: we like parameters of order of 0.1-1.
The quick answer is that there must be some mechanism behind the entire setup that makes the mixing tiny. And this is where it starts to be tricky (and funny too)... Designing such a mechanism.
This reminds me of the simpson chapter where Homer enters a world of mirrors where his 3D version is found :p. It would be interesting to see a version of each of us in another dimension.
hahaha I don't know if this has anything to do with what you just said in your content...:P
This has actually nothing to do with my content. But this was fun to read (I haven't seen this Simpson episode, but I can definitely visualise it :D )
Once again these topics are really strange and interesting at the same time.
For instance, the fact that we know about the other world and also measure some "signals" from there, but how can we get there to see what's really going on?
Or is this impossible?
You say that the chemical situation is different from our "level". How could life be organized there?
Or is life impossible in other dimensions thus we were never able to travel there?
Are these dimensions, therefore, more abstract rooms, we can't get into with our state of mind?
I know it's a pretty sci-fi-like comment by me.
Thanks for stimulating my mind in this way.
Best Chapper
Actually, we must say "we could know" instead of "we know". We have a way to probe the mirror world, but so far there is no sign of it in data. Consequently, this will constraint the theory. Inversely, if we have a signal of something, you can be sure there will be in no time hundreds of theoretical interpretation of it. Then we need time, more data and more global analyses (investigating many channels and signatures) to see which one of these theories could hold and which one is just wrong.
The un-famous 750 GeV excess of the LHC is a good example of this: 400 theory papers explaining an excess who disappeared after a year [fun fact, I only wrote one and I was claiming that either our knowledge of the strong interaction is wrong, or the excess is fake; I was right!] :)
I am glad to read this! Have a nice week-end!
One personal question: Do you think that the scenarios drawn in various sci-fi movies and literature (beaming, living in various worlds, intelligence of the universe...) could be reality???
I do not think so personally, as these movies are generally flawed completely from the physics standpoint.
However, note that this has nothing to do with we is called "mirror world" here (except the name).