The Strange Case of Quantum Time Loops And Testing Backward Time Travel

An exploration of The Strange Case of Quantum Time Loops And Testing Backward Time Travel.
My Patreon Page:
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My Event Horizon Channel:
/ eventhorizonshow
Papers:
"Nonclassical Advantage in Metrology Established via Quantum Simulations of Hypothetical Closed Timelike Curves", D. Arvidsson et al, 2023
journals.aps.o...
Music:
Intermission in D by Miguel Johnson
migueljohnson....
Dark Fog by Kevin MacLeod is licensed under a Creative Commons Attribution 4.0 license. creativecommon...
Cylinder Eight by Chris Zabriskie is licensed under a Creative Commons Attribution 4.0 license. creativecommon...
Source: chriszabriskie...
Cylinder Five by Chris Zabriskie is licensed under a Creative Commons Attribution 4.0 license. creativecommon...
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Darkest Child by Kevin MacLeod is licensed under a Creative Commons Attribution 4.0 license. creativecommon...

[@the_algo_rhythm]

I actually watched this tomorrow.

[@username27626]

talk about outing yourself for being late to the party 🫵😂

[@Kawaiijihad]

.worromot siht dechtaw yllautca I

[@Oldwhiteguy]

I rewatched it a week ago

[@tomski1111]

I watched this yesterday

[@perks6292]

I knew you were going to say this yesterday

[@gewitterhund3164]

"We dont serve particles that move faster than light" A tachyon comes into a bar.

[@the_algo_rhythm]

"You did tomorrow!", the tachyon replies.

[@Epoch11]

Took me a second but that's pretty good

[@holycow666]

"Wanna hear a joke?"

[@Matt.Willoughby]

Tachyons are only hypothetical

[@gewitterhund3164]

@@Matt.Willoughby You must be the star on every party

[@dylanfoster7037]

I love how John has a seemingly endless supply of video topics to make that are always as interesting as the last. Keep on killing it my guy.

[@jamesofallthings3684]

Well he does make videos about the universe.

[@Error_5383]

And it just keeps getting weirder. I don't understand why people have to turn to religion for spirituality. Quantum science IS magic. If you can't find spirituality in string theory, you're not really paying attention.

[@BriarLeaf00]

He's the best in the KZbin game, no doubt about it. He's a genuinely curious mind.

[@SchmelvinMoyville]

Keep on killing it my guy 🤓🤓🤓🤓🤓🤓🤓

[@Bellphorion]

It's not endless, I've watched it all 😢

[@omnijack]

“A message came through as soon as the machine was activated, before the scientists could send their first question. The response itself was worryingly brief, containing only four words: TURN THE MACHINE OFF.”

[@StevenBara]

Or: "Fly, you fools!"

[@amciuam157]

This quote sounds familiar but I can't make it out. Book?

[@StevenBara]

@@amciuam157 Lord of the Rings. The quote is from Gandalf when he fights the Balrog most prominently. But I believe he says it at least once more in the books.

[@friedrichjunzt]

That would be really spooky -- and what would we do? Turn it off and call it a day?

[@benjiunofficial]

"UNDER NO CIRCUMSTANCES GO TO P4C-970"

[@BaronVonQuiply]

I travel backwards in time whenever I want. To be clear, time is still going forward, I'm just facing the other way.

[@jameswilkes451]

Technically if you could look into the 4th dimension this could be true...

[@LuisAldamiz]

Time is facing down in fact... you should lay on your back, I guess.

[@harrywilliams9290]

Option 1: The entangled particle updates its state to the other particle FTL. Option 2: The entangled particle updates its state to the other particle backwards in time. I say: What's the difference? Great show, John!

[@timgreenglass]

or its all part of a simulation. there is no spooky action at a distance because there is no distance.

[@FlashRayLaser]

Reminds me of a neat thing about antimatter. We generally choose to model antimatter as matter with opposite charge, but it turns out you get the same mathematical values if you instead think of it as regularly charged matter that's simply traveling backward in time at an opposite temporal rate from standard matter. I say if the concepts are mathematically identical, they are identical, and both are just ways of interpreting it.

[@THX..1138]

🤔....Option 3: Very low mass particles like those that can be entangled don't experience time like more massive matter and thus from their perspective were never separated at all.

[@AlexanderShamov]

​@@FlashRayLaser This raises questions about irreversible physical processes. How would the entropic arrow of time work for antimatter? How would quantum measurement work? A single particle may not care about such things, but if a macroscopic amount of antimatter really went back in time in any meaningful sense, it would experience a very weird reality.

[@robrick9361]

I'm Jacob Godier watching this on the Titanic. I just wanted to comment before we go down how proud I am of my great great grandson John. Good job son.

[@Maxtyur]

Ha ha ha ha ha ha ha ha ha ha ha ha ha ha ....CRINGE.

[@bobbyjamesramsey4860]

Yeah, Jon rules!

[@jacobjohnson2603]

shut it down fellas @Maxtyur says it's cringe!!!!!!!

[@Astra2]

I can't believe it took me until 2032 to find your channel!

[@tfunkman]

Welcome! Glad to have you with us! Check out John's spooky videos. He does his version of the Simpsons Treehouse of Horrors during October 😁

[@PROFESSOR_BUTTER]

Funny i have finished all video this channel provede in 1044

[@ArthurHuizar]

Goodnight y'all

[@danielscottjzx100]

Good morning from Australia

[@stuartspence3613]

Morning in Australia ... now there's a twist, it's morning in England too. Honest

[@sethreynolds3704]

You already slept tho

[@lampshade34]

Good night brother

[@syko2164]

Happy 2020... what could go wrong.

[@inthesky3833]

saving this one for my late night watch, title already has me excited

[@AlexWalkerSmith]

PSA: Einstein's "spooky action at a distance" wasn't about quantum entanglement. He was talking about the supposed "collapse of the wave function". He thought that because the actual collapse is not observable, it can't be real. Quantum entanglement doesn't mean doing something to one quantum particle affects another particle. Instead, think of it like how if you break a cookie in half, you only need to look at the jagged edge of one half to know what the other half's jagged edge looks like. The properties are correlated, and no matter how far you separate the two halves of the cookie, there will always be that correlation. But if you do something to one half of the cookie, nothing happens to the other half. There is no "action" in a correlation.

[@Dipj01]

"He thought that because the actual collapse is not observable, it can't be real." Can you tell me why he thought that? All this is very interesting...

[@AlexWalkerSmith]

@@Dipj01 Put simply, Einstein thought wavefunction collapse can't be real because it would be spooky 😜 I'm not a quantum physicist, but as I understand it, Einstein didn't like the idea that a wavefunction can exist in a superposition (existing in all possible positions simultaneously) then instantaneously become in a specific particle-like position due to an outside interaction (like being measured). It's that instant collapse Einstein said would be "spooky", because it wouldn't obey the universal speed limit ("C"). Therefore, he thought, it can't be what actually happens.

[@ll7868]

If we set up a way to communicate with the future the first message could be "Be excellent to each other and party on, dudes!" followed by a kickass guitar solo.

[@brianSalem541]

the website FutureMe makes that possible

[@TheOldTeddy]

You have surpassed previous posts I must relisten to, this one will take several listens. From in the past I praise you :)

[@ClellBiggs]

This is a good one. Made my head spin for a few seconds.

[@mattparker9726]

LOVE THIS ONE!

[@EdwinDominguez]

Thanks Jhon. These video reminds me of one of my favorite Xfiles episodes "Clydebruckman Final Repose" when he says "What happen if i help you, and then, you help the mother of the time machine inventor? , he would go back in time and The US never invade Granada" its something like the future changing the past

[@JohnMichaelGodier]

Oh yeah, that's a classic and one of my favorites also.

[@EdwinDominguez]

@@JohnMichaelGodier John so very glad for your answer, keep the good work! as always!!

[@the_algo_rhythm]

Oh, man. I totally got that confused with Jose Chungs' From Outer Space. Clyde is the one who sees everyone's death, right?

[@nickbusker725]

Amazing episode!!!!

[@MCsCreations]

Fascinating stuff! Thanks, John!!! 😃 Stay safe there with your family! 🖖😊

[@mattparker9726]

John, this was so good I had to listen to it 3x IN A ROW. Never done that before on any video on KZbin, ever. Your content is some of the densest, and thought provoking on KZbin. An instant click from me!

[@Dx-fv9ww]

Another awesome video JMG 💙

[@stevoplex]

Help! I'm stuck! Everyone is zipping past me at the normal speed of time, while I'm stuck in the Nervous Breakdown Lane, going nowhere. And it's a Studebaker, not a DeLorean. And I kinda feel like a character trapped in a Franz Kafka story.

[@Ki_Adi_Mundi]

Disengage.

[@NicholsonNeisler-fz3gi]

Go for a walk

[@jlee1014]

Excellent explanation! Needs to be added to the mindblown playlist. Thanks again!

[@andrewpark6260]

These vids are like time travel...I put them on and next thing I know it's morning.

[@rayrous8229]

A world with a changing history. Sounds like madness.

[@syko2164]

Sounds like modern era.

[@DrBusiness9]

Sounds like all of time…

[@boobah5643]

That's one of the big problems, isn't it? If you can go backwards in time with a time machine, then time will change... until you reach a point where history is changed such that the time machine isn't invented. This implies that even if time travel is _technically_ possible, it still can't be done and stay done.

[@Voshchronos]

@@syko2164 im 14 and this is so deep

[@DollarGeneral_Is_a_Plague]

I got up and walked in a circle twice during this video. It was intense. But I just couldn't walk backwards

[@BlackShardStudio]

Retrocausality (or time-independent causality) is my preferred explanation of entanglement. I don't believe time's arrow is truly fundamental; a newly created particle only acquires this "forward" temporal direction through interactions between particles. Think of it like placing a leaf on a stream: the molecules of the leaf initially have no preferred direction. They only acquire momentum in the same direction as the stream due to the net motion of water molecules around them. This is why entanglement appears to act instantly; information about particle interactions travel in every temporal direction until the particle gets caught up in the current. This is also why quantum effects disappear and entropy appears as a result of measurement.

[@aalhard]

10:48 I had another argument about this, but then you told me tomorrow so yesterday I changed my mind🤯

[@skister82]

Someone should conduct a time experiment at my in-laws house because i swear time slows down to a complete stop whenever im there. Maybe it has something to do with that huge life sucking object that nothing can escape from? Anyway enough about my mother in-law.... I do wonder why as individuals we can perceive time differently, for example when were enjoying ourselves time moves so fast but when were bored or dont want to be somewhere time seems to slow down. An old work colleague once told me to keep busy all day because it brings hometime quicker. John thanks for the great content as always, you're one of the best to ever do it.

[@RobertGrosse]

Thank you so much for ideas herein that I hadn't yet heard - such as retroactive causality - love it :) love your programs really get a person thinking. Will be watching this one several times to take it all in.

[@takster050974]

That was an amazingly interesting video. Thanks jmg.

[@robbabcock_]

Mind bending stuff, JMG!

[@guillaumemaurice3503]

Thank you for the video the topic was very interesting & fascinating.

[@because-strudels]

What a fascinating video. This is a topic discussed widely, but seldom as interestingly as this.

[@TheSepetto]

My brain fried from this video. This needs an animation my man.

[@michaeltape8282]

That was freaking fascinating. Thanks, man!

[@joeblog2672]

Nice job here. Good synopsis of some more modern and conventional time theory. This retrocausal bit reminds me of hearing about a famous dinner party Stephen Hawking had put together back around 2009. He arranged a very hush hush party at his house on a particular day hoping for guests to arrive that night. However, he didn't send out any invitations until a day later! Regrettably nobody showed up on the night of the party! They certainly would have been interesting guests!

[@tiagotiagot]

You can't send messages with entanglement because you can't measure or alter the state of the particle without breaking the entanglement, so even without time-travel; you will just share new random knowledge about the particle but not actually "write" anything in the particle in a way that the entanglement survives.

[@hakrj12]

What about this: I have 16 tubes each one containing one entangled particle. You, on the other side of the universe, have 16 tubes each containing its pair. I want to tell you "Hi" so I break the entanglement in a specific order to represent the binary equivalent. Ex. Entangled = 0 Not Entangled = 1 Your machine then sees which particles are still bonded and displays 01001000 01101001 (Hi)

[@Dipj01]

@@hakrj12 wow, that's actually interesting. I wonder if any real physicist would like to give an opinion on this

[@wildfoodietours]

Just before bedtime, perfect timing once again.

[@CyberscapeCity]

Create a gauge theory of time to quantize time using the Weyl Group as the gauge group. You can incorporate the effects of Closed Timelike Curves by using winding numbers that sum over looping paths either forwards or backwards around the Closed Timelike Curve. If time is quantum, you can have indeterminate causal structures and potentially entanglement within temporal fields. Also check out the two state vector formalism / transactional interpretation.

[@jamespahl3832]

HOLY SHIT THE END OF THIS STARTED BLOWING MY MIND LOVE YOU JMG

[@joshuafindley791]

Back to back!! Such a great day!

[@holdenbell1630]

From what I understand, many people, including some physicists misunderstand how quantum entanglement works. It actually does not violate the speed of light. It requires the receiver particle to be placed prior and then you know it's rotation is the same or opposite from the entangled receiver particle. It's like this. You give Jimmy and Mary a letter each. One has an up arrow, the other had a down arrow. You randomly give each of them their letter. They go on their separate ways, Jimmy to New York City, and Mary to Paris. Jimmy opens his letter to find it is an upwards arrow, meaning Mary's is down. No speed of light violations were caused here because they had to travel at non-relativisitc speeds to get to their new positions.

[@holdenbell1630]

It's like saying, when you move a laser pointer across the Moon by flicking your wrist quickly is causing the dot of light to move faster than the speed of light.

[@Dipj01]

I think this exact thing too. But I'm not a physicist and since many physicists don't mention this, I think maybe I'm missing something.

[@egggge4752]

In classical quantum mechanics the particle has no up or down until observed. What you are describing is super determinism. Its the idea that how the wave function collapses is somehow pre-determined. Physicist hate this idea since you cant prove or disprove it since every observation would be determined you couldnt control it with a non-determined observation. But this is 100% how it works. Everything else is stupid af.

[@giannismargaris9553]

@@egggge4752 i am not 100% sure but i think certain experiments were caried out, even recently, just to see wether the entagled particles were already predermined. I think the answer was a legit no, meaning that quantum entaglement legit carries information from one particle to another.

[@atypical1000]

This just seams to end up with exactly the same problem as regular quantum entanglement communication, ie you can't watch an entangled particle to see if it changes because that is a measurement. So as soon as you watch it, you collapse it's wavefunction and you will never know whether it was you or your communication partner, either separated by distance or time, who collapsed it first and since the collapse to a specific state is random, how can it carry meaning? You can't wait for a particle's state to collapse or choose the state it collapses to.

[@ifsowhynot]

Quantum entanglement communication is unfeasible for me, but only because it requires a communication partner

[@shiddy.]

really good one

[@remygallardo7364]

I actually just went and saw the Back to the Future musical a week ago and it was fantastic! It stuck remarkably well to the source material, though what changed was totally valid. Their practical effects work to get the car scenes to function was on point.

[@manachromeYT]

Just in time

[@PlanetXtreme]

Wow. Excellent video and great thought experiments. Also related, at a recent family gathering I compared the stainless steel of the Delorean to the cybertruck. Still love that Delorean tho.

[@cabanford]

Considering watching this yesterday

[@binbots]

General relativity and quantum mechanics will never be combined until we realize that each individual observer is observing them both at different moments in time. Because causality has a speed limit (c) every point in space where one observes it from will be the closest to the present moment. When one looks out into the universe they see the past which is made of particles (GR). When one tries to measure the position of a particle they are observing smaller distances and getting closer to the present moment (QM). The wave property of particles appears when we start trying to predict the future of that particle. A particle that has not had an interaction exists in a future state. It is a probability wave because the future is probabilistic. Wave function collapse is what we perceive as the present moment and is what divides the past from the future. GR is making measurements in the observed past and therefore, predictable. It can predict the future but only from information collected from the past. QM is attempting to make measurements of the unobserved future and therefore, unpredictable. Only once a particle interacts with the present moment does it become predictable. This is an observational interpretation of the mathematics we currently use based on the limited perspective we have with the experiments we choose to observe the universe with.

[@mattparker9726]

3:25 I think there are two aspects of timelines at play in a possible backward time travel scenario. I'll call them a "fixed" time line, and a "variable" timeline. The first only comes into play with the time traveler if the grandparents issue comes up, VIZ: the universe is structured in such a way that is impossible to do. This applies to all causality events related to the vanishing of the individual doing the time traveling. Then there are the decisions and events that DON'T affect the individual (the case of Andrew Carlssin seems to bear this out) they are unaffected by the first "fixed" timeline, and thus, create an alternate universe with that specific variable being changed.

[@benjaminallen3595]

john Mikey godchild!! thanks for the upload :)

[@marshallodom1388]

If you have two wormholes go in one come out and go in the other, but while traveling move the end of the first one you went in in a circle close to the speed of light. When you come out the second one you'll see yourself going into the first one.

[@disideratum]

Retrocausality! Wheee!! 💫🤓💫

[@howtoappearincompletely9739]

Curling is a surprisingly interesting sport to watch.

[@timgreenglass]

one can get swept away.

[@ddmarty]

I love your channel, for one because your videos get me to think about things I had no idea about. About the grandfather paradox if we go back in time. I've heard that we just go on different timelines if we change something in the past. Like, if we convinced our grandparents not to marry, it would set them on a different timeline. Much like observing something changes it. Also, with all due respect, I think we're finding out from JWST we don't know a whole lot about the universe, much less black holes.

[@timothycronenweth2293]

Retrocausality. I loved your scenario and the experiment. I would not be surprised if there is some way to test this in the future. Or should I say past...

[@An-Islander]

What kind of time travel is it when you wake up in the middle of the night and are having trouble going back to sleep so you open YT to play something soothing only to see JMG!s latest video dropped 46 seconds ago?

[@valinorean4816]

Thanks, but I'm in a rush now, I'm gonna watch this yesterday

[@DanielGenis5000]

Delightful, paradoxically!

[@PoppabearsCave]

Thank you teacher!

[@weevil_bob]

5:25 6:00 I thought about this after watching vertitasium's video about black holes and they talk about what it'd be like going into and through a singularity. They mention a universe on the other side with negative gravity but then I thought wouldn't that virtually be the universe running backwards.

[@Voshchronos]

Made me think about the Arrival movie, which plays with this concept of sending information to the past.

[@hectorolivas7122]

woah man

[@efdangotu]

We cant travel back in time, but information from the past travels into the future at a relative rates. We can peer into the past as a crystal, or a mirror. We can predict the future by measuring the crystal as it forms in real time.

[@jimmyzhao2673]

My brain hurts.

[@yurkdawg]

I've always thought of the "twin paradox" to be a "paradox" not because of the age difference, but because if speed is just relative, what is the difference between the first twin travelling near the speed of light, and the second twin, who while staying home, appears to be travelling near the speed of light relative to the one on the ship? There are answers to resolve this paradox, usually involving acceleration and or that the first twin has to stop then travel back to the first before comparing ages. But the "paradox" is that if you truly buy that "everything is relative" then technically each twin is moving compared to the other thus one shoul not age while the other does not. (Lol or "does age?" Heh you know what I mean...(lol I hope ;)) The scenario in your video is more interesting though

[@AlexanderShamov]

It's really simple mathematically and there's nothing paradoxical about it. In usual Euclidean geometry a straight line between two endpoints is the shortest path between them. The twin paradox is the exact analog of this fact for spacetime geometry. The key insight here is that the "metric" on spacetime measures what's called proper time - the amount of time that passes for the observer moving along the given path. Now, instead of the shortest path between two points we should be looking for the worldline with the _longest_ proper time between two spacetime events. And that, again, is the straight line, i.e. the trajectory of an inertial observer. Hence the twin paradox: the twin who stays inertial esperiences longer proper time (i.e. ages more) than the one who goes on the journey.

[@michaellowe3665]

So if you take 2 entangled particles and parked one, while the other circles a cyclotron for an hour at near the speed of light, does the still one lock down its state exactly when the other is measured or before?

[@FrankJohnson-r3e]

Yeah yeah yeah well I'm going to watch it yesterday 🙄 Ride the tachyon wave, baby! 😎

[@davidschaftenaar6530]

Retro-causality sounds like a misnomer. In order to cause anything you need to interact with it. That means 'sending' some form of information, which isn't allowed at rates faster than the speed of light; It sounds more like you're measuring a predetermined outcome. A hidden variable. You're not shaping the past, but only coming to know it.

[@michaelbruns449]

Our bizarre holographic reality may actually exist within a super massive black hole and earths biosphere is its singularity.

[@goodluckfox]

Yes! 51 seconds since posting I’m the first to watch! :) Love your videos I listen to them on my way to wooooooooooork. :)

[@failogy]

Thank you for your video. But please consider mix sound less bass, it will be easier to listen.

[@zach11241]

Even though I watched this before I watched this, I still don’t really grasp it. I’ll have to watch it again yesterday.

[@immortalsofar5314]

So the three theories on quantum entanglement are: 1. It's spooky (A. Einstein) 2. Information moving FTL. 3. Information going backwards in time. Might I add: 4. The information is set at the time of the entanglement and we have a fundamental misunderstanding of quantum uncertainty? I mean that's very vague and unhelpful but, of the four, it seems the most likely so using that as a negative data point might open up whole new vistas of research.

[@hilltop4847]

Damn this one was 🔥🔥🔥

[@ctrsmithy]

I think time travel could be possible but any changes wouldn't effect the timeline you came from but will start a alternate and separate timeline from that point onwards.

[@joelyons3713]

Super interesting!

[@MrWizardGG]

I really enjoy thinking about the infrastructure of the universe

[@b.griffin317]

There was a low-budget indy film many years ago (I forget the title) about a team who create a time machine that is able to send them back in time only as far as the machine itself existed. They stored it in a rental storage unit but then some shadowy group or agency was hounding them about it and they descended into paranoia. Reminds me of this. Was supposed to be based on real, if speculative, science as one of the film makers who was also one of the actors was a STEM major or something.

[@monolalia]

Primer?

[@benjiunofficial]

Sounds like Primer. Great movie. Underlying theme was that if you instigate a paradox, it's not the universe that breaks, it's you.

[@nigelrhodes4330]

If you think of space as a 4D hyper-spheroid where time loops back on itself at a smaller scale than the other dimensions and where the forward motion of time is emergent at the scale we live. This is basically the premise of closed time-like loops, this can also help to explain the non-locality of the universe hinted at by entanglement.

[@LuisAldamiz]

I'm all for retrocausality but only for photons (and other massless particles). Massive particles should behave differently because they can't travel at c.

[@mattparker9726]

8:30 and because of this, not only do I think we can have FTL communications, but also teleportation and FTL spaceflight. But lets go with the communication angle. If you "know" the particle's position, that would be a 1. if it is unobserved, that is a 0. Thus, FTL binary code is achieved. (at least that's how it works in my mind.) If that's not the case, this is why I'd like to speak to you and Avi together, you because your ideas are awesome, and Avi, because he can do the math. Moving on to FTL spaceflight, I know you and Avi would both say it's impossible to go faster than light because mass increases and therefore you must have infinite energy, etc. etc. OK, well picture this scenario, in a magical universe, you HAVE infinite energy, and you are accelerating towards C, along a fixed line, being observed by another person at rest. What can I see? Redshifted or blueshifted light depending on my position, sure, but what happens at exactly the moment when you go into superluminal flight? Will you become invisible to the observer? Will you freeze into a static image? Is there some sort of shockwave, in much the same way, as a jet going supersonic? (this is something I think SETI should try and find, as a techno signature) If so, what does THAT look like, and can we model or test any of this? And regarding teleportation, if a single molecule can seemingly teleport, isn't that simply a matter of energy input to make multiple particles do the same thing?

[@hakrj12]

What about this: I have 16 tubes each one containing one entangled particle. You, on the other side of the universe, have 16 tubes each containing its pair. I want to tell you "Hi" so I break the entanglement in a specific order to represent the binary equivalent. Ex. Entangled = 0 Not Entangled = 1 Your machine then sees which particles are still bonded and displays 01001000 01101001 (Hi)

[@jasonallsopp68]

Right off to work

[@LaboriousCretin]

Thank you for sharing. FTL in a circle is not exactly backwards in time. Even forward it's just a backwards evolving light source. Though I do like thinking about Godel universe or closed time like curves or tipler cylinders. Manyworlds and ocums razor. To much when it can be explained easier. Many possible states. Why have they not looked at tunable metamaterial for a slit? Not to get into if traveling back in time. Leads to universe splits and such to keep congruence of a time line. The quantum backwards in time is a short time and more of a math trick than actually going back. But it also gets to a old theory. What if a photon or electron could time travel and make the universe. A good brain puzzle for kids. Things like cherenkov radiation and such helping them solve why not.

[@ramunaspovilanskas9944]

Great!

[@knightswarm1]

Mind blown!

[@aaronjennings8385]

The Einstein-Rosen Bridge, also known as an ER bridge or wormhole, is a theoretical concept in physics that proposes a connection between two distant points in spacetime. The ER bridge is a result of the collaboration between Albert Einstein and Nathan Rosen in the 1930s. They hypothesized that these bridges could connect two black holes, effectively creating a tunnel through spacetime. The concept of ER bridges has been linked to quantum entanglement through the ER=EPR conjecture. This conjecture, proposed by physicists Juan Maldacena and Leonard Susskind, suggests that entangled particles are connected by a wormhole, effectively creating a bridge between them. This bridge is not a classical, physical connection but rather a quantum mechanical one, where the entangled particles are linked through their shared quantum state. In essence, the ER bridge as entanglement implies that when two particles are entangled, they are connected by a quantum wormhole. This wormhole allows for instantaneous communication between the particles, even if they are separated by vast distances. The entanglement creates a shared quantum state that transcends spacetime, effectively linking the particles in a way that defies classical notions of distance and communication. This concept has significant implications for our understanding of quantum mechanics and general relativity. It suggests that spacetime itself could emerge from quantum entanglement and that the mysteries of entanglement could be resolved by understanding the geometry of wormholes. The ER=EPR conjecture has sparked significant interest and research, as it potentially bridges the gap between quantum mechanics and general relativity.

[@RealBelisariusCawl]

The biggest issue I see with any form of time travel is that, when free will is introduced, it would be incredibly easy to induce a paradox state. Example: Say, in the Twin Paradox, your younger twin decides after seeing you, that he/she does not want to continue the journey. Why? Because why not see what happens, obviously. Well… what happens? The most logical explanation given the evidence presented by the double-slit experiment is that at the very moment when the paradox is introduced, the fabric of reality itself would alter and you would not have any recollection of meeting yourself, only that you have decided to not continue. Photons LITERALLY will retroactively change their states after passing through the slits when observed. Reality, as far as I can tell, is able to read and write information without respect to time or the conventional laws of physics. My personal running hypothesis is that any attempts to “break the game” as it were and for lack of a better phrase (my reticence comes from the fact that I don’t want to get into Simulation Theory right now and I fear that turn of phrase will inevitably become the focus) will be corrected in some manner imperceptible to us. Schrödinger’s cat *has* a determined state - let’s say alive - but if we muck with the variables too much then it’ll go from being alive to being and HAVING ALWAYS BEEN dead. As if reality itself holds a grudge against us for our observations. This mysterious universe is more strange and wonderful than I think any of us really could ever know.

[@conradsieber7883]

Just don't think problematic paradox is the reason time travel to the past is prohibited. There are probably good reasons it can't happen but the "universe" caring about problematic paradox doesn't sound like one of them to me. Why should the universe care if some time traveler erases his own existence?

[@theoldman5896]

Thank you. "Muh paradoxes" is such a silly idea. I'd even argue there is "bo such thing" as a paradox in any way shape of form (as far as physics is concerned)

[@MadSpectre47]

Can we get a "Here Are Ten Spooky Messages You Don't Want to Receive From the Future" video?

[@JerehmiaBoaz]

Can we really observe the curvature of spacetime by gravitational lensing instead of just the curvature of space? Can we really measure that light traveling through curved spacetime undergoes gravitational time dilation when it's already at maximum time dilation because it's traveling at the speed of light? IOW can a stopped clock run even slower and how would you measure that?

[@squirlmy]

As soon as someone (or some group) invents backward time travel, other people from the future are going to go back and try to take over time travel for themselves, possibly taking away credit for the invention for themselves. The movie "Primer" explains this well, for such a low budget film. In other words, if you invent time travel, you are doomed to defend that invention for eternity.

[@jonathancohen7788]

Good call. “Primer” is one the more fascinating films of the past two decades.

[@bounceday]

Their machine only goes back to when they started it though

[@LuisAldamiz]

Problems were/will be so big that people from the future actually used time travel to destroy time travel itself at the origin. Not sure how the paradox was solved but it worked/will work.

[@jota6262]

Two (related) features of the Universe that are a bit odd- matter cannot travel faster than the speed of light and cannot go back in time. There may be other rules of the game but those are at the top. So somebody or something at the beginning decided those time travel scenarios we enjoy in science fiction will forever remain there.

[@jakemiketta3868]

Time travel to the past will be real soon 🔜.

[@TheBIGchaPOWski]

I will be asleep 5 minutes after this comment. Thank you.

[@ilirlluka6789]

The reason why I have never believed that backwards time travel is possible is not the issue related to paradoxes, for me personally the solution to the paradoxes that might arise is your own frame of reference. You go to your past but the past to which you travelled to has now become your future and thus even if you kill your younger self or your grandfather it would not have a retroactive effect upon you. However, in my mind, the issue with backwards time travel has always been related with the question "does the past exist anymore?". The past would have to be "recorded" (pardon the modernist digital era semantics, cannot think of a better word than "recorded") or "stored" somewhere in order for you to "access" it. Does not matter if one means "travel" to the past or "reverse" time, locally or otherwise, although "reversing" entropy for the whole universe seems like an even greater impossibility that just you "travelling" to the past. Sure, if we are talking about parallell universes then yes, you could "access" that past timeline, but if we are not talking about a multiverse (which I do not think it exists as it opens a whole new can of worms of paradoxes) or new branches of universes being constantly created, but just this single universe, then time travel seems impossible. I am aware these concepts cannot be presented In detail in a KZbin comment but I hope you get what I mean. [Disclaimer] I am not a physicist, neither a physics philosopher, these are just my personal thoughts based on "intuition" let's call it, I do not pretend to know anything more than anyone else on this subject.

[@PseudoGuido]

Time, Dr. Freeman? Is it really that time again? It feels as if you only just arrived.

[@digitalplayland]

Uroboros. The universe is a sphere. The curvature is moving FTL, self-sustaining itself. Immortality. So cool.

[@whatisbestinlife8112]

There's the idea in the film Primer that, basically, everybody experiences their own timeline. And that whatever "new" timeline that is generated by traveling backward in time and altering any events is experienced by them now. Any paradox only exists in their perceptions of their own timeline. Which does fit into the nature of our existence that we all truly only have our own frame of reference to experience our lives. We cannot experience what other's do, directly. They can relate their experiences to us in various ways (what artists, writers, etc do, essentially) but we cannot firsthand experience what others do. Time travel paradoxes then simply only exist in the time traveler's head. Why we think there is one big common timeline is simply a result of there not (yet) being anyway to travel back in time (we know of) that could then potentially alter past events. So we all experience what we only think is one big common timeline but is in fact a specific one for each of us that simply happens to all be exactly the same because no past-event alterations have (yet) taken place to the individual timelines. And thus the only real "danger" of time-traveling (not accounting for the extreme ethical considerations of altering others' lives so fundamentally) results from the potential of ending up with multiples of the same person stuck in a that person's timeline because one who was supposed to travel back in time in the future does not then actually do so for whatever reason when that timeline eventually reaches that point, and thus the two overlapping copies continue on together in the world. There is no danger of the more fantastical (though fun for film storytelling reasons as in Back to the Future) "A paradox that causes collapse of the space-time continuum so we must save the universe, Marty!". Or the more mundane "your parents ended up not having kids now you fade from existence". The big potential problem is duplicates. The now overlapping copies being a logistical, practical problem for them to have to sort out. Not some "reality destroying paradox". More along the lines of they only have one identity, family, house, etc but two of them and who gets it all? Again, this is all based upon the idea that we all experience timelines specific to ourselves that just so happen to be exactly the same because no one has yet figured out a method of going back in time to alter events. Unless the Mandela Effect is actually a legit thing and we are sensing such anomalies... ;)

[@ThexBorg]

If gravity affects the tick of time, then civilisations, and other interstellar bodies existing in gravity wells, and or travelling through the universe at super high speeds, experience time at different rates. A civilisation living in high gravity star system like a supergiant star, would live in a high gravity well which would affect their experience of time different to humanity.

[@howaboutataste]

Fun fact: retrocausality used to work. It reached a saturation point at which most antimatter was annihilated and dark energy and dark matter were created.