The Paradoxes of Time Travel

Ah way back when Sean was still in the 4:3 timeline.

i think it’s great we still have videos like this around from before we could time travel

Work: “can you be here in 20 min?” Me: “That’s outside my light cone”

I watched this at 2am while drunk hoping it would lull me into sleep but it was so interesting I stayed awake for the entire lecture. There's something about the way Sean Carroll talks that really resonates with me.

i wish i could go back in time and give this man a glass of water

I made a travel back in time in the year 2010 and was able to see a conference of S. Carrol...

When first started watching this, I was tempted to stop because I felt it was going to be above my head. Ironically, this man took a magnificent approach of explaining these laws of physics, in a way that I actually understand everything.

I wish Youtube would remember the timestamp that i fell asleep at so i can finish the lecture 😭😂

I think Sean is keeping something back. He has obviously travelled through time. Here in 2023 he looks at least 10 years younger than he did last week.

Thanks for uploading this talk so we can all (re)watch it.

The main problem understanding time travel is that we don't really understand what any kind of travel is, at a fundamental level. We know how to travel through space, if we want to, I can get up and walk over there, but we don't really know what that means at a fundamental level. So, the reason we don't know the answer is that we don't really understand the question sufficiently well. For instance, there are two quite different notions of "going back in time". According to one of them, I, as I am now, could somehow be transported back into the Middle Ages and find myself living in that time, complete with my memories of the future. According to the other notion, you could somehow "wind time back", so it is the Middle Ages again, but you won't be present there. You won't exist until you are born much later. The difference between these two notions corresponds to two very different ways of understanding time. One is that time is something that you travel through, albeit with no choice. The other is that somehow you are in time, but it passes. It makes all the moves, so to speak, you don't move within it.

Here’s one reason, in physics. one could not visit their past self: Conservation of mass- In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so the quantity can neither be added nor be removed.

Proof that he will present anywhere. Kudos.

I love the confidence here not to admit that there may be things he doesn't know. It's like some tribal leader 5000 years ago saying we will never get to the moon because boats only move on water. 😅

One thing I find interesting, is that if you could travel back in time and would find yourself there, what would the both of you be made of? If you could duplicate matter like that, you could basically create infinite amounts of it, which would mean that there would be a huge exploit in our universe. Either, matter/ energy is constantly flowing through our universe and no particle is actually the same from one moment to the next, or then something would happen to either one of the versions to make it disappear, because you couldn't have the same matter in two places at once. Also, the only way I can even begin to imagine time travel to the past is by removing oneself from the confines of whatever here is, and going outside space time, and placing themselves back into space time in a different location. Here again, you would be creating matter out of nothing, thus duplicating yourself, thus possibly creating a paradox of who is the real slim shady and actually owns the atoms one is made of.

I can't get enough of Professor Carrolls lectures. He speaks so well and is a fantastic teacher. Love his use of real world associations. Some serious & some humorous.

At the start of "Principia Mathematica" Newton says "For the purpose of this demonstration I must assume that space and time are fixed and immutable" so it must have occurred to him that they might not be.

Time only flows one way, like a river. If you want the river to flow in a different direction you need to change the shape of everything surrounding the river

Because there is no actual time, if we ever were to travel though what we perceive as time, it would actually be traveling to previous conditions. Both the "Past" and "Future" are information so if you did manage to seemingly travel to the past what you would be doing is accessing the information set of our physical reality in a particular position in the universal information set. Like skipping to chapters on a DVD to your favorite scene. As for not being able to travel faster than the speed of light, there are short cuts that allow you to get from point A to point B faster anyway, if not instantly, and that is utilizing columnar standing waves aka "Wormholes". These waves are like a tesla tunnel that can get you from earth to a distant star system 444.2 light years away without the bother of having to travel from here to there. The amazing thing about standing columnar waves is they can reach through incredible distances without distortion or interference from the physical world in between the two ends. It has been said that mathematics and geometry were not invented, they were discovered. This is a clue to how apparent time travel would be possible and how you would go about doing it and once our quantum AI computers reach singularity we can just sit down and ask it how to do it. In the meantime why not just put to bed all of your preconceived notions about the great pyramids and reexamine them with all of the above in mind.

In the depths of paradox, where timelines entwine, The mysteries of time travel, a complex design. A journey through epochs, past and future's embrace, Yet the paradoxes of time, we must carefully trace. The past is a realm where we yearn to explore, To rewrite the chapters, to even the score. But change the past's thread, a paradox unfurls, Affecting the future, in unpredictable whirls. The butterfly's wing, a small act in the past, Can lead to a tempest, a change unsurpassed. The ripple effect, in time's endless sea, A paradox that challenges what's meant to be. And what of the future, that enigma so grand, Can we alter its course, with a time traveler's hand? A paradox arises, a loop to contend, For how can we change what's yet to ascend? The grandfather's paradox, a conundrum profound, If you travel to kill, does logic astound? If you end your own lineage, your existence denied, A paradox that leaves the mind mystified. The twins of relativity, time's constant refrain, One travels through space, the other remains. A paradox unfolds, as time slows and bends, In the depths of the cosmos, where reality rends. In the heart of these paradoxes, we find the key, To the essence of time, its enigma and decree. For as we journey through its intricate weave, The paradoxes of time, they ask us to believe. In the dance of past, present, and future's embrace, The paradoxes of time travel, a celestial chase. A reminder that time, in its essence and prime, Is a riddle we unravel, through the corridors of time.