We Will Never Invent Time Travel

[Deleted]

You all have false concepts of what time is. The measurement of passing reality created by us humans that puts a number next to an event cannot be back-tracked upon.

[Deleted]

Please explain how colliding photons at near-light speed proves that multiverses and "multidimensional" universes exist? :|

I think he's just mixing the search for evidence that we live in an 11-dimensional universe with the theory of the multiverse.

Btw, we don't need that any of the parallel universes have a slower moving time to travel to their present that would correspond to our past. We just need that they would have started "later" in a secondary time axis of the underlaying structure of the multiverse. Just because our universe has only 1 temporal dimension, it doesn't mean that the multiverse is limited to that.

And it's true that real time travel will never be possible but, think about this. You start in the Universe A, year 2012, and travel to universe B, with a later big bang, so it's at year 1929, where you kill Hitler. Now you want to go back to the year 2012 with Hitler dead... it's easy! you just have to go to a Universe C that is currently in the year 2012 (big bang same as your universe), but which was modified from an alternate, but identical, version of you from a Universe D with an earlier big bang than A who did exactly the same thing as you did!
Zing! you achieved to live in the universe (actually, one of the infinitely different infinite universes) that enjoys the consequences of you having killed Hitler in 1929.

---------- Post added 2012-11-01 at 09:53 AM ----------

You all have false concepts of what time is. The measurement of passing reality created by us humans that puts a number next to an event cannot be back-tracked upon.

Oh sorry, so you are more correct than the standard model and the general relativity put together! :O awesome!

[Collected]

If we ever do invent time travel, then surely at some point in that potentially infinite time that time travel was present, then someone will have used time travel to travel back to before this date, thus we would already know that we invent time travel, as we would already have time travel. Am I right?

The other theory is that today is 01/11/2012 without time travel. If in 2050, someone invented time travel, and travelled back to 01/11/2012.. then another version of this day would be created where time travel messed with it.

So 01/11/2012 without time travel ever being invented.
And 01/11/2012 where in 2050, time travel was invented, and someone came back to this day.

Two versions of the same day based on different events in the future.

[Deleted]

You all have false concepts of what time is. The measurement of passing reality created by us humans that puts a number next to an event cannot be back-tracked upon.

Whaaaa? The only thing you said was :* Time cannot be revisited* in a really really fancy way.
Care to elaborate on exactly what is the true concept of time?

[rt7]

I think he's just mixing the search for evidence that we live in an 11-dimensional universe with the theory of the multiverse.

Btw, we don't need that any of the parallel universes have a slower moving time to travel to their present that would correspond to our past. We just need that they would have started "later" in a secondary time axis of the underlaying structure of the multiverse. Just because our universe has only 1 temporal dimension, it doesn't mean that the multiverse is limited to that.

And it's true that real time travel will never be possible but, think about this. You start in the Universe A, year 2012, and travel to universe B, with a later big bang, so it's at year 1929, where you kill Hitler. Now you want to go back to the year 2012 with Hitler dead... it's easy! you just have to go to a Universe C that is currently in the year 2012 (big bang same as your universe), but which was modified from an alternate, but identical, version of you from a Universe D with an earlier big bang than A who did exactly the same thing as you did!
Zing! you achieved to live in the universe (actually, one of the infinitely different infinite universes) that enjoys the consequences of you having killed Hitler in 1929.

---------- Post added 2012-11-01 at 09:53 AM ----------



Oh sorry, so you are more correct than the standard model and the general relativity put together! :O awesome!

no one on this thread has even given a single mathematical equation to back up their claims, it's just a load of theorycrafting by nerds



everyone is suddenly an expert on the internets

[MasterHamster]

Oh sorry, so you are more correct than the standard model and the general relativity put together! :O awesome!

The closest we'll ever get is time dilation

Whaaaa? The only thing you said was :* Time cannot be revisited* in a really really fancy way.
Care to elaborate on exactly what is the true concept of time?

Little more than "X seconds ago, Godzilla was over there, now it's here."

[Deleted]

no one on this thread has even given a single mathematical equation to back up their claims, it's just a load of theorycrafting by nerds

Multiverse isn't a theory with equations and mathematicy stuff. It's a hypothesis to explain the information loss that happens at the collapse of the wavefunction. Just take it as something fun to have fun with. So yes, it's a load of theorycrafting by nerds, so what?

Why so serious?

---------- Post added 2012-11-01 at 10:21 AM ----------

The closest we'll ever get is time dilation

Not really.
-General Relativity: in the normal, only-slightly-curved spacetime, you can move in any direction you want, but you can only move forward in time. But if you get close to a black hole and travel past the event horizon, then the situation inverts: You can move forward and backwards in time, but spatially you can only move closer to the black hole. So general relativity allows for travel backwards in time. You just can't do it for long, nor tell anyone else about it (any signal you send will not get past the event horizon).

-Standard Model of Particle Physics: particles are indistinguishable from their antiparticles if we reverse the time arrow of the antiparticle. So, antiparticles are just particles travelling backwards in time. According to this interpretation, particle-antiparticle pair creation and annihilation are "simply" a single particle performing a causal temporal loop (like travelling to the past to impregnate your younger grandma and be your own grandfather).

[MasterHamster]

Multiverse isn't a theory with equations and mathematicy stuff. It's a hypothesis to explain the information loss that happens at the collapse of the wavefunction. Just take it as something fun to have fun with. So yes, it's a load of theorycrafting by nerds, so what?

Why so serious?

I enjoy science fiction just like everyone else, but whenever I stumble into threads like these, it's filled with frankly ridiculous ideas. And a very clear misunderstanding of what "time" is. It's not some universal database, it's just how we measure events as they occur.

"Time travel" forward is possible in theory, by accelerating to incredible speeds, causing time for the travelers to slow down slightly compared to the time experienced by bystanders. Traveling backwards in time is a whooooole other issue. It's like assuming that there's some kind of accessible database storing all occurred states of mass. It's simply ludicrous.

[raddry]

As someone already said, if time travel into the past was possible, then we would already know about it since there would be time travelers right? When speaking of time travel why do you assume that the instant we live in is the latest? And since we don't have time travelers, it can mean one of these 4 things:

1: It's not possible
2: Multiverse: Each time one does it he goes into another 'timeline' and we live in one that hasn't happened
3: It's possible but we killed ourselves before advancing to such a technology
4: It is possible and we did it but it's actually regulated so we don't see any sightings of time travelers

[Deleted]

I enjoy science fiction just like everyone else, but whenever I stumble into threads like these, it's filled with frankly ridiculous ideas. And a very clear misunderstanding of what "time" is. It's not some database, it's just how we measure events as they occur.

"Time travel" forward is possible in theory, by accelerating to incredible speeds, causing time for the travelers to slow down slightly compared to the time experienced by bystanders. Traveling backwards in time is a whooooole other issue. It's like assuming that there's some kind of accessible database storing all occurred states of mass. It's simply ludicrous.

Time is a dimension. It can bend, curve and distort just like space. It has a "microscopic" (more like plank's-scale) structure according to the Standard Model. There should be spacetime "particles", if you will. So no, it's not just "how we measure" the progress of the entropy in the universe, it's not a man-made concept to tag onto causality. It has a physical existence just like photons, black holes and gay republicans.

Travelling backwards in time is possible. As i pointed out in my previous post (you might have missed it, it was an edit), both General Relativity and the Standard Model conceive (not at all abnormal) situations where travelling backwards in time could be happening routinely.
Maybe it's just not possible for us.

[Lora]

99% of you are just parroting something you read in a science mag

most of you are still in school or barely out of it

basically stop watching so many sci-fi movies

This is a highly compelling argument. Everything already is and there really is no "inventing". Time travel exists already, we just are not aware of it. Time is not a line but actually from a non-linear, non-subjective viewpoint - it's more like a big ball of wibbly-wobbly, timey-wimey; stuff.

[semaphore]

The theory of general relativity does suggest a scientific basis for the possibility of backwards time travel in certain unusual scenarios, although arguments from semiclassical gravity suggest that when quantum effects are incorporated into general relativity, these loopholes may be closed.

Well, as much as I commend you for your efforts, General Relativity by itself does not forbid closed timelike loops (the bad things, travel to the past etc). There are solutions which allow for it, some simple ones that are incompatible with observations of our universe (a former costudent wrote a thesis about one), and more complicated ones that are somewhat less incompatibe (wormholes etc). But GR is obviously incomplete, and multiple universe sounds too much like a cop-out to me, which of course is horribly subjective

Yeah, you're right; I'm aware that there are some hacks in relativity that could potentially suggest allow time travel. But the reason I say "not really" is because those are all rather farfetched. Adding on what iadamson says, there doesn't seem to be any way to actually build a time machine on such basis without violating energy conditions. So relativity doesn't really allow time travel. Personally, I think Hawking's conjecture may very well turn out to be correct.

[Deleted]

Travelling back in time may still be possible if the Multiverse hypothesis is correct.

Exactly what I was going to answer. The multiverse theory removes all the drawbacks and inconsistencies of traveling back in time.

It just means multiple timelines exist right next to eachother. And traveling back in time doesn't mean that we will notice it here.

---------- Post added 2012-11-01 at 02:07 PM ----------

The other theory is that today is 01/11/2012 without time travel. If in 2050, someone invented time travel, and travelled back to 01/11/2012.. then another version of this day would be created where time travel messed with it.

So 01/11/2012 without time travel ever being invented.
And 01/11/2012 where in 2050, time travel was invented, and someone came back to this day.

Two versions of the same day based on different events in the future.

And both can exist at the same time, we just aren't aware of the other versions since we aren't part of it.
So no, we can't rule out backwards time travel on something so simple. The multiple dimensions / multiverse theories remove the inconsistencies.

[Deleted]

Yeah, you're right; I'm aware that there are some hacks in relativity that could potentially suggest allow time travel. But the reason I say "not really" is because those are all rather farfetched. Adding on what iadamson says, there doesn't seem to be any way to actually build a time machine on such basis without violating energy conditions. So relativity doesn't really allow time travel. Personally, I think Hawking's conjecture may very well turn out to be correct.

They are not really farfetched. If they "curvature" of the spacetime is steep enough that not even light could escape from it (a black hole), within that metric you can actually travel back in time. The price you have to pay is that you cannot ever get out. Some people call it cosmic censorship: strange and amazing things happen beyond the event horizon, but we cannot see them (light cannot escape from it). The only way we can is if we agree to pay the (very expensive) toll.

What Hawking's conjecture, btw? that information "lost" in the black hole is retrieved through Hawking's radiation?

[semaphore]

They are not really farfetched. If they "curvature" of the spacetime is steep enough that not even light could escape from it (a black hole), within that metric you can actually travel back in time. The price you have to pay is that you cannot ever get out. Some people call it cosmic censorship: strange and amazing things happen beyond the event horizon, but we cannot see them (light cannot escape from it). The only way we can is if we agree to pay the (very expensive) toll.

The thing is, we have no evidence of closed timelike curves existing in reality, or that it can even exist. For instance, once you bring quantum theory into play, it appears that energy tends towards infinity near a Cauchy horizon, i.e. where the Kerr metric says closed timelike curves can supposedly be found. Which means that General Relativity breaks down at a Cauchy horizon, and therefore any prediction by General Relativity there - inclduing a closed timelike curve - would most likely be wrong.

What Hawking's conjecture, btw? that information "lost" in the black hole is retrieved through Hawking's radiation?

I was refering to the chronology protection conjecture. It's absolutely an open question right now, I just meant that I personally think it's right.

[Waaldo]

The only possible way you could know that we will never invent time travel is if you invent time travel, go to the future, and see that we never invented time travel. What if time travel can only go back far enough from when the machine was first activated?

Don't get me wrong, I don't believe time travel will ever be possible because time isn't an object that can be traveled through. But I won't say it will never exist because there is no possible way that anyone will ever know until it is invented.

---------- Post added 2012-11-01 at 10:38 AM ----------

This is a highly compelling argument. Everything already is and there really is no "inventing". Time travel exists already, we just are not aware of it. Time is not a line but actually from a non-linear, non-subjective viewpoint - it's more like a big ball of wibbly-wobbly, timey-wimey; stuff.

+1 that was the best possible response to his comment.

[someotherguy]

As someone already said, if time travel into the past was possible, then we would already know about it since there would be time travelers right?

if someone has technology to travel into the past, why can't they have technology to be invisible and untouchable?

And another question: If we cannot find answers to all questions on this forum, does it mean there are no answers to the questions?

[twinkleblur]

i have my own theory about time travel. the reason we cant do it is basically we cant go back in time to a point we didnt pysically exist. so if your 50 years old you can only go back 50 years. also with that going back in time you will also grow younger meaning going back in time to the day before you invented the time machine would erase you having a time machine. with that. where ever you were before going back in time you will be at that place with no memory of ever using or creating a time machine.

[Deleted]

I can't even think of a reason I would want to travel back in time..

[Tradewind]

I can't even think of a reason I would want to travel back in time..

Dinosaurs, duh. The real question is how far back are you going to go to see them...