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Message 46 of 46 (826386)
12-29-2017 4:28 PM
Reply to: Message 43 by Phat
12-20-2017 9:39 AM
Re: The Cosmic Toothpaste Tube
Sorry for the delay, busy with the family at Christmas.
|Explain to me in a nutshell the prevailing theories on the concept of multiverses.|
So in a nutshell, there's really only two. They're not competing in any way, both could be true, as they deal with separate issues.
In Quantum Mechanics we have the Many-Worlds interpretation. In brief, unlike most theories of physics, the maths of quantum mechanics doesn't come with a clear mental picture of what is going on. So there are several "narratives" people use to picture the maths mentally. Many-Worlds is one such.
It basically says the universe has several parallel timelines. In one timeline an atom decayed, in another it didn't. Two separate histories. Now in science fiction this is usually presented as "every possibility" occurs, but that isn't true, only a small range of histories are possible and most don't differ all that much. I can say more about this, but it becomes a bit technical, keeping in mind having a nutshell answer.
Genuinely different universes with totally different laws. Maybe a world with ten dimensions and nine forces, rather than four dimensions and four forces like ours. Worlds where gravity works differently so that things spin when they fall. Places where relativity isn't true. Totally different worlds. Some theories of particle physics suggest this. In most models of this conjecture there are a lot of such different universes.
Again, both could be true. Our universe might have several timelines and there could be separate universes as well.
|Are they realistically plausible?|
The first type (multiple timelines) has no evidence against it yet, despite some attempts to falsify it. However all the evidence can still be explained by orthodox versions of Quantum Mechanics, so the jury is out. In other words, it makes predictions we can verify and those predictions hold up, but other ways of looking at Quantum Mechanics also make those predictions, so hard to know.
The second type has no strong evidence in its favour, but we're not advanced enough to perform the necessary experiments. It's the kind of thing that may need to wait until we colonise space.
|Could we hypothetically exist in multiple dimensions?|
I'm taking this to mean "does the universe we live in possibly have more than four dimensions?" So far the evidence is strongly against this, we seem to exist in a four dimensional reality. Predictions of theories with more than four dimensions have been shown to be wrong.
|How does a mathematician connect the hypothetical to reality?|
For the different universes or multiple dimensions theories the connection takes one of two forms.
They predict something about particles, e.g. an extra species or maybe a change in how they collide with each other. For example if we live in four dimensions photons flying toward each other bounce off each other 0.00012% of the time, but if there is a hidden fifth dimension they bounce off each other 0.00027% of the time.
Or they predict something about the heat signature of the big bang, e.g. if there are other universes out there, the should have affected the big bang and the cold patches in the big bangs after glow should be 0.0045% cooler than they would be otherwise.
For the multiple timeline theories, going into the way you connect it to reality would go outside the nutshell scope, it's a technical enough topic.
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| ||Message 43 by Phat, posted 12-20-2017 9:39 AM|| ||Phat has acknowledged this reply|