Physicist May Have Solved The Grandfather of All Time-Travel Paradoxes : science

[–] [email protected] 32 points 2 months ago (2 children)

This the paradox where you go back in time and fuck your grandfather, right?

[–] [email protected] 39 points 2 months ago* (last edited 2 months ago) (1 children)

No, it's the one where you fuck your grandmother because the man you thought was your grandfather was an in-the-closet homosexual. Then you produce your father, who then produces you. But you've got to travel 1,000 years into the future and hook up with a hot but socially awkward cyclops mutant before you can do any of that.

[–] [email protected] 23 points 2 months ago

I did do the nasty in the past-y.

[–] [email protected] 19 points 2 months ago* (last edited 2 months ago) (3 children)

By reasoning, and through use of quantum statistical mechanics, Gavassino shows the time tourist's own entropy can't continue to grow as they 'go back', with quantum fuzziness effectively canceling expected disorder to create a parallel entropic timeline that begins and ends at the same points.

closed time loop diagram

Entropic arrow of time (gray arrows) flipping between entry and exit points of a closed timelike circuit. (Gavassino, Classical and Quantum Gravity, 2024)

What would that look like for the contents of the temporally looped spaceship? Processes that we might expect to be linked to entropy would necessarily change, potentially reversing.

Circling back to a spry young grandfather courting your grandmother the first time, the time loop could make his untimely death reversible; your memory of why you ever wanted to murder him in the first place may be erasable. In other words, all bets are off in a closed loop where quantum physics smoothes out any intrusive entropy

[–] [email protected] 6 points 2 months ago

I don't remember murdering my grandfather. Trust me, if you'd known him, it would have been on your bucket list too.

[–] [email protected] 5 points 2 months ago (1 children)

Is there a translation for Community College grads?

[–] [email protected] 4 points 2 months ago

Translation: following time travel, everything resets to exactly as it was before time travel.

Not exactly groundbreaking, considering this is assumed by the premise of a closed timeline curve.

[–] [email protected] 4 points 2 months ago

A quick skim of what you copied makes me think of Steins;Gate lol

[–] [email protected] 15 points 2 months ago (1 children)

This is bullshit.

[+] [email protected] -8 points 2 months ago (2 children)

Says the random person on the internet in response to the quantum physics professor who says otherwise.

[–] [email protected] 6 points 2 months ago (1 children)

I take it you did not read the article.

[–] [email protected] 0 points 2 months ago (1 children)

I did, actually. So, what makes it “bullshit?”

[–] [email protected] 4 points 2 months ago

Dude.

First off, it's purely a hypothetical model. You can plop in negative time to equations and have them make sense, this doesn't mean that negative time is possible.

However disregarding that. The abstract of the study:

We study the internal dynamics of a hypothetical spaceship traveling on a close timelike curve in an axially symmetric Universe. We choose the curve so that the generator of evolution in proper time is the angular momentum. Using Wigner's theorem, we prove that the energy levels internal to the spaceship must undergo spontaneous discretization. The level separation turns out to be finely tuned so that, after completing a roundtrip of the curve, all systems are back to their initial state. This implies, for example, that the memories of an observer inside the spaceship are necessarily erased by the end of the journey. More in general, if there is an increase in entropy, a Poincaré cycle will eventually reverse it by the end of the loop, forcing entropy to decrease back to its initial value. We show that such decrease in entropy is in agreement with the eigenstate thermalization hypothesis. The non-existence of time-travel paradoxes follows as a rigorous corollary of our analysis.

So the study the article is based on concludes that time-travel paradoxes are impossible. Thus you can not kill your own grandfather because it'd create a paradox. What they're saying is that you could be in a CTC (closed time-like curve) where in which time goes back and forth from your grandparents to you and back again, but the time going back would reduced entropy ie reverse things.

So you couldn't "go back" because that'd mean your entropy ie your arrow of time, was still pointing forwards and not backwards.

This isn't a case of some random Lemming against a professor saying otherwise. It's Lemmings telling you you've bought into pop-science sensationalism.

The article does actually communicate what I explained there, but really almost hides it with the language, so I'm not surprised your either didn't read it, missed it, or didn't internalise it:

Circling back to a spry young grandfather courting your grandmother the first time, the time loop could make his untimely death reversible; your memory of why you ever wanted to murder him in the first place may be erasable. In other words, all bets are off in a closed loop where quantum physics smoothes out any intrusive entropy.

Ie nothing here is breaking the Novikov self-consistency principle

[–] [email protected] 2 points 2 months ago (1 children)

You violate causality, you better bring more than some popsci bullshit to the table.

[–] [email protected] 2 points 2 months ago (1 children)

And you’re the arbiter of what constitutes “popsci bullshit” rather than the quantum physics professor? Such hubris.

[+] [email protected] -3 points 2 months ago* (last edited 2 months ago) (1 children)

[removed by mod]

[–] [email protected] 4 points 2 months ago (1 children)

In my experience, people with rational reasons for rejecting claims can articulate said reasons, rather than simply calling them bullshit and telling other people to fuck off. I’m not convinced of the article’s claims, but I’m also not convinced you know what you’re talking about either. The difference is that the article admits its claims are speculative and hypothetical, while you’re just slinging insults.

[–] [email protected] -2 points 2 months ago* (last edited 2 months ago) (1 children)

Rejecting causality IS the rational reason. It is you who is irrational. When one scientist brings forth a claim that breaks ALL of physics, with ZERO empirical evidence support such an astounding theory, it is not the ones who doubt that are likely to be wrong.

[–] [email protected] 0 points 2 months ago (1 children)

It read to me like they provided a reason for denying causality though: that the associative breakdown in entropic state suggests causality can be violated. I don’t have the expertise to evaluate that claim, but if you do, why don’t you just explain to me why it’s wrong? Or is that demanding too much of a random person on the internet?

[–] [email protected] -3 points 2 months ago (1 children)

Uh, because the entire field of physics is completely fucked if causality is violable? I'm really done with you.

[–] [email protected] 3 points 2 months ago

That’s good, because I’m pretty sick of you too. What an arrogant POS.

[–] [email protected] 8 points 2 months ago

[–] [email protected] 7 points 2 months ago (3 children)

I thought there was an understanding of infinite timelines already. You can never change your past. As soon as you do, it is no longer "your" past. It is now another you's past. That's why time travel is useless unless it's not you changing your past.

[–] [email protected] 6 points 2 months ago

That hasn’t been proven yet. All of this shit is still theoretical. AFAIK, time travel into the past isn’t possible in our current understanding of physics.

[–] [email protected] 4 points 2 months ago

Or it’s a recording and we can view it but not interact.

[–] [email protected] 2 points 2 months ago

Depends on whether you subscribe to the many worlds interpretation or not.

If not then you can still time travel as long as it follows the Novikov self-consistency principle

[–] [email protected] 6 points 2 months ago* (last edited 2 months ago) (1 children)

Smoke a joint of Purple Haze and it'll do the same thing.

[–] [email protected] 5 points 2 months ago

Thanks for the reminder, I got some green, yay!