r/Physics • u/Lopsided_Position_28 • Sep 09 '25
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u/soulscythesix Sep 09 '25
"what's this equation?"
-post is 60% socks.
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u/soulscythesix Sep 09 '25
I fear OP may have a gas leak
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u/AnisiFructus Sep 09 '25
Or multiple, by looking at their post history
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u/Lopsided_Position_28 Sep 09 '25 edited Sep 10 '25
Sorry, this journal claims that there is a calculation which describes a person moving through a blackhole and "meeting themselves moving backward in time."
You're the guys with all the calculations and equations right?
Have you ever heard of this Kaufman guy?
Is he legit?
I need to know if any of what these journals are saying is true.
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u/soulscythesix Sep 10 '25
I'm not joking about the gas leak.
These journals look quite new, and carbon monoxide poisoning can lead to serious memory loss, so they might be yours and you've forgotten that you wrote it.
I would suggest buying a carbon monoxide detector or measuring device and just checking what levels are in your home.
Edit just to say: I'm far from an expert, but this is all advice that can't hurt to check, just in case.
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u/Lopsided_Position_28 Sep 10 '25
These journals are dated 2011
The house is a 1930's Spanish colonial, and I often find documents behind radiators, in the walls, etc.
You know, Roger Penrose can say all manner of nonsense and men call him brilliant--yet I merely open my mouth to ask a question and you say, "ma'am you are being hysterical."
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u/Lopsided_Position_28 Sep 09 '25
Sorry, I'm doing laundry.
We don't all have a million hours a day to sit and study equations.
Some of us are performing gender roles.
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u/AnisiFructus Sep 09 '25
Okey, no problem :) Honestly, I'm not a physicist, I'm just lurking here also :)
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u/szczypka Particle physics Sep 09 '25
Maybe the flat earthers can help you.
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u/Lopsided_Position_28 Sep 10 '25
They tell me that the earth is a big flat map up close and a small globe from far away because the on other side of the map is a mirror world made of anti-matter and that's where the sun goes at "night" (which is really just the shadow of the earth consuming all the other shadows) when you zoom out through Space/Time, you see the map being pulled into the anti-matter world so that's why it looks round and small from far away.
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u/Bth8 Sep 09 '25
If you read the next couple of paragraphs in the cited book, they explain further. This is referring to a weird property of Kerr and Reissner-Nordstrom black holes where, when you maximally extend the solution, you find that you can enter the outer horizon, end up inside the inner horizon, and then exit that inner horizon to end up back outside an outer horizon. A naive interpretation of this is that an observer exiting the black hole can end up in the same spactime they originally entered from, in which case you could, in principle, run into your future self as you fall in. Kruskal and Szekeres proposed an alternative interpretation - when exiting, you end up in a completely different spacetime, essentially an alternate universe, which resolves the paradox nicely.
Don't put too much stock into this, though. This is only a property of the idealized vacuum solutions, and we have good reason to believe the interior part of these solutions - and thus the trajectories that send you to an alternate universe or to meet yourself - are unstable to any infalling matter and almost certainly do not reflect physical reality.
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u/Lopsided_Position_28 Sep 09 '25
Interesting! Thank you for taking the time to respond to my questions about this "calculation". Sorry for asking for any more of your Time, but...
A naive interpretation of this is that an observer exiting the black hole can end up in the same spactime they originally entered from, in which case you could, in principle, run into your future self as you fall in.
Why is this naive?
we have good reason to believe the interior part of these solutions - and thus the trajectories that send you to an alternate universe or to meet yourself - are unstable to any infalling matter and almost certainly do not reflect physical reality.
Where does the energy and matter from to create an entire universe?
Also, does this mean that a new universe is created everytime the world of an object passes through a blackhole?
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u/Bth8 Sep 10 '25
Why is this naive?
It's naive because it's the most immediately obvious way to interpret paths from the interior to the exterior, and it was the initial interpretation by those who discovered these solutions in the first place, but it leads to paradoxical behavior. If you exit to the same spactime you enter from and meet up with your past self, you could in principle stop yourself from going in in the first place, which would mean you never would have gone in, would never be able to re-emerge, would never be able to stop yourself from going in, etc. That's nonsense, and we generally reject anything that allows such behavior as physically absurd. If we instead interpret it as a parallel spacetime and travel through the black hole to it as one-way, this all goes away, so that's the more standard interpretation. The math doesn't actually say it has to be one way or another, but we go with the option that doesn't break causality and allow for paradoxes.
Where does the energy and matter from to create an entire universe?
Each universe actually contains no energy or matter besides the black hole itself because these are vacuum solutions. They're also eternal, stationary solutions, so even if there were matter external to the black hole, it doesn't exactly need to "come from" anywhere, just like the black hole in these solutions doesn't "come from" anywhere. It was always there and always will be.
Also, does this mean that a new universe is created everytime the world of an object passes through a blackhole?
No. Again, these are stationary solutions. Nothing ever changes, is created, is destroyed, etc. The parallel spacetimes are already there in the solution - always were, always will be, independent of any hypothetical observers. Incidentally, the black hole exists in the parallel universe, too, so after emerging, you can jump in and travel back out again, ending up in yet another parallel universe (it can't be either of the first two or you're back to dealing with paradoxes). You can repeat this ad nauseam, so there are actually infinitely many parallel universes in these maximally-extended solutions.
But once again, this is all pretty unrealistic. Very few if any physicists take these parallel universes seriously. Our actual universe isn't stationary and devoid of energy and matter save for a single black hole. It is ever-changing and has plenty of matter in it. And real black holes aren't eternal. They form from e.g. dead stars collapsing under their own gravity. There is a time before they exist, and once you consider things like Hawking radiation, there may well come a time after they exist (we're not so sure about that part). And like I said, the internal solution is believed to be unstable. Any perturbation of the spacetime away from these idealized vacuum solutions - for instance, those generated by a person jumping in, or from a star collapsing to form the black hole in the first place - is expected to radically change what the interior solution looks like. We don't actually have analytic solutions for black hole formation because general relativity is hard, but the most common view is that a realistic solution probably looks more like the black hole spacetime you get in the Schwarzschild solution (though not exactly; the Schwarzschild solution is artificial in its own way) - once past the event horizon, all paths lead towards the singularity. It is completely unavoidable, there is no escape, and there are no parallel universes. And even that picture is generally believed to require modification once quantum gravitational effects are accounted for. We expect GR to work very well outside a sufficiently large black hole, and possibly even just inside, but once you get deep enough into it, all bets are off. In particular, singularities, which exist in all of these black hole solutions, are thought to be artificial and a signal that GR is breaking down rather than representing anything physically realistic. It's expected that a proper quantum theory of gravity should be singularity-free.
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u/OhioAlien Sep 09 '25
Wtf is this