Theories - Time Travel, Parallel Dimensions, Etc.

[nog]

By that do you also include time dilation? Because that definition applies (based on which point of observation is being considered) and time dilation is a proven fact.

ETA: Though I suppose you do pass through the intermediate times with time dilation even if it doesn't seem so from the point of view of the one whose clock is sped up.

I do not consider time dilation to be time travel. That's the reason why I tried to be clear with a short explanation of what I mean by time travel.

 

[FortyTwo]

I do not consider time dilation to be time travel. That's the reason why I tried to be clear with a short explanation of what I mean by time travel.

Yeah, I know what you mean. I didn't read into it enough initially and when I edited my post it basically just contradicted what I had brought up in it previously.

But I disagree with you there. I'd consider time dilation on a major scale to be time travel, as described by Steven Hawking in the video I posted in this thread earlier.

 

[nog]

But I disagree with you there. I'd consider time dilation on a major scale to be time travel, as described by Steven Hawking in the video I posted in this thread earlier.

It's possible to have a similar effect, but I don't consider it time travel, it's time dilation.

I didn't like that video though, it's misleading. It left out important information like based on specific observers. Time on the train doesn't slow down, it slows down as observed by an outside observer. According to everyone on the train, time is moving right along just fine, there is no 'slowing down' on the train. They also left out the length contraction part (as viewed by an outside observer).

If you want to run the numbers, let me know how long it would take a person to have any appreciable time dilation. You can run two sets of numbers, one the maximum acceleration a person can withstand and live a somewhat acceptable life, and another based on g. I think you'll find it's a rather long time. Unless we come up with some kind of inertial dampeners (/geek).

 

[FortyTwo]

It's possible to have a similar effect, but I don't consider it time travel, it's time dilation.

That's fair.

I didn't like that video though, it's misleading. It left out important information like based on specific observers. Time on the train doesn't slow down, it slows down as observed by an outside observer. According to everyone on the train, time is moving right along just fine, there is no 'slowing down' on the train. They also left out the length contraction part (as viewed by an outside observer).

You're technically right, but you have to remember this is made for a more general audience - it's a part of Into the Universe with Stephen Hawking (unless it's one of the separate programs that he does, I'm not sure, he does a lot of them now but I remember seeing that one years ago). Time simply seems sped up to those on the train because they are undergoing the effects of time dilation. It is true that a hundred years pass, and it is also true that a few weeks pass - simply depending on who you ask, because time is an artificial concept created by our attempt to understand how things change.

If you want to run the numbers, let me know how long it would take a person to have any appreciable time dilation. You can run two sets of numbers, one the maximum acceleration a person can withstand and live a somewhat acceptable life, and another based on g. I think you'll find it's a rather long time. Unless we come up with some kind of inertial dampeners (/geek).

And another thing. By assuming that we have the kind of technology that will allow us to go at near-light speeds, which we haven't even barely approached in the past with any kind of craft, we can also assume that we'd have the kind of technology that would allow for a human to survive at those speeds without discomfort. By the time we got to one it's reasonable to assume that we'd have the other, and even if we didn't it's still all hypothetical anyway. All we know is that if we had the proper technology, it would work.

Hawking himself says at the end of the video that such a train would likely be impossible even with future technology. In the actual special (cut off of the video) he goes on to explain how a more plausible method would be through space travel. We've already observed space-traveling humans/equipment having lagged as a result of the high speeds that are required to launch and that are observed while orbiting the Earth, even if the time difference is very slight (I think it said something like 0.007 seconds). The point is, we know it can happen, even if it's not realistically achievable right now.

 

[nog]

You're technically right, but you have to remember this is made for a more general audience

Yeah, I understand that. I just think it gives the wrong impression. To me, an important part of relativity is that it depends on perspectives. To me this distinction is extremely important. From the person moving in a space ship (or train) (and relative to Earth), they experience no time dilation nor length contraction and view the rest of the universe as length contracted and time dilated. However from the person not on the space ship, moving at a different velocity (say stationary to the Earth) they view the space ship as length contracted and time as slowing down. I really don't like videos like the one portrayed showing, as viewed from on the train (and even described from aboard the train) as time being slow.

I think the subject matter is difficult enough and misrepresenting it does a disservice to the intelligence of the audience and makes it more difficult for those really trying to understand it.

Perhaps that's all my hang-up though.

And another thing. By assuming that we have the kind of technology that will allow us to go at near-light speeds, which we haven't even barely approached in the past with any kind of craft, we can also assume that we'd have the kind of technology that would allow for a human to survive at those speeds without discomfort. By the time we got to one it's reasonable to assume that we'd have the other, and even if we didn't it's still all hypothetical anyway. All we know is that if we had the proper technology, it would work.

I guess that's an assumption I'm not willing to make yet.

Sorry to derail your thread.

On topic, I don't agree with the Big Bang model. I have mulled over other ideas, but I think there's something missing in current cosmology. I think ideas like dark matter and dark energy simply signify our lack of understanding and are similar to epicycles on Ptolemy's model. They're a stop-gap to try to fix an inaccurate model.

 

[Blobbenstein]

I like the idea that, the matter in the Universe evaporates some how(maybe proton decay), time 'stops'(although it doesn't really, but time needs matter to measure itself by, or something), some of the radiation re-condenses as matter, and you get another big bang, and the whole cycle starts again.

I don't think the BB started as a singularity; it probably starts off quite big; my guess is the Schwarzschild radius for all the matter in the Universe*, except with the topology of a 3-sphere.



*would that be 100million light years(not including dark matter)?

 

[K-II]

I theorise that humans won't last long enough to figure out how the universe really began, and even if we did, we'd hit a wall of 'you'd have to exist beyond your existence to test this' and ultimately suffer a frustrating, answer-less extinction.

 

[FortyTwo]

Yeah, I understand that. I just think it gives the wrong impression. To me, an important part of relativity is that it depends on perspectives. To me this distinction is extremely important. From the person moving in a space ship (or train) (and relative to Earth), they experience no time dilation nor length contraction and view the rest of the universe as length contracted and time dilated. However from the person not on the space ship, moving at a different velocity (say stationary to the Earth) they view the space ship as length contracted and time as slowing down. I really don't like videos like the one portrayed showing, as viewed from on the train (and even described from aboard the train) as time being slow.

That's not how I took it, but I can imagine that's how some people saw it. Which understandably pisses me off a little, because now there are X more people running around uninformed. But I just try to interpret things as I see them, I guess.

I think the subject matter is difficult enough and misrepresenting it does a disservice to the intelligence of the audience and makes it more difficult for those really trying to understand it.

Perhaps that's all my hang-up though.

Not really, I can see what you're saying.

I guess that's an assumption I'm not willing to make yet.

Sorry to derail your thread.

I'm not ready to say we'll ever get the technology to do such things, but the entire situation is hypothetical to begin with. We can only predict what would happen if the conditions were to end up becoming realistically achievable, based on what we know about relativity and what we've already observed on a smaller scale, and that's what I was getting at rather than implying that it was within the realm of possibility in the near future.

Although, you never know. Smartphones probably would have seemed like an insane rambling to someone who lived in the 30s. Aside from Tesla, who would have probably invented one made out of tin foil and grocery bags.

And no, you didn't derail it at all. I was hoping for this sort of discussion when I started it.

On topic, I don't agree with the Big Bang model. I have mulled over other ideas, but I think there's something missing in current cosmology. I think ideas like dark matter and dark energy simply signify our lack of understanding and are similar to epicycles on Ptolemy's model. They're a stop-gap to try to fix an inaccurate model.

I think the Big Bang happened but it's too hard for us to understand the nature of it to make any quick assumptions. There wouldn't have been any sort of bang to begin with because sound didn't exist yet. We can't know what started it because before it time didn't exist yet. And these facts alone show how little we understand things that are on that big of a scale.

I think Dark Matter and Dark Energy are basically the equivalent of someone who has never heard of animals being asked what their favorite animal is, and their reaction being a shrug and a vague mention of their favorite type of plant.

 

[Blobbenstein]

I think the Big Bang happened but it's too hard for us to understand the nature of it to make any quick assumptions. There wouldn't have been any sort of bang to begin with because sound didn't exist yet.

but if you were to transport back to just after the big bang(whatever it is), the effect on your eardrums might be similar to that produced by a loud sound.

 

[K-II]

Aren't dark matter/energy just named that because we can't directly see them?

 

[FortyTwo]

but if you were to transport back to just after the big bang(whatever it is), the effect on your eardrums might be similar to that produced by a loud sound.

No.

If you were to transport back in time just after the Big Bang - given that this is actually possible and not just Science Fantasy - several things would happen:

1.) You would not technically exist because there is no medium for you to exist.
2.) If you manage to survive not existing, you would be crushed by the fact that the Universe, even when unimaginably big, was ridiculously dense before, during, and right after the Big Bang considering the fact that everything that exists and has ever existed has to fit into a small area because no other area exists yet.
3.) Even disregarding the first two options there would be a lack of breathable oxygen and you would suffocate as you would in any other area of open space.
4.) You would not see, hear, smell, feel, or taste anything because the chemicals that respond to those sensors don't exist yet in anything but their purest form, which is basically just barely differentiated energy. Note that light also doesn't exist yet. Think of how unimaginably dark that would be. You know, if your eyes hadn't imploded yet from not only a lack of atmospheric pressure but the fact that pressure doesn't exist yet because there's no matter (in the strictest sense of the word) for pressure to be applied to.
5.) Nothing is stable. Nothing. Not even the things we know as stable today. They simply haven't gotten to that point yet. Right then it's just a bunch of unstable proto-particles going about their business in a maddeningly unpredictable manner that we can't even relate to because our laws of physics were barely newborn at this stage.

 

[FortyTwo]

Aren't dark matter/energy just named that because we can't directly see them?

Basically, but what I think nog was getting at is that, by trying to name and categorize things like this, we are acting like we understand things which we can't even begin to fathom at this stage in our development.

It took us until earlier this year to prove the Higgs field and that is one of the most fundamental things about the Universe. Imagine how long it could take to not only prove that the effects we observe in space are due to substances we can only assume are there to make up for what we don't know, but to sufficiently understand these substances.

 

[Blobbenstein]

what I mean is: your body, along with your eardrums, would be blown away.......'similar' to what a loud sound might have on your eardrums...

 

[FortyTwo]

what I mean is: your body, along with your eardrums, would be blown away.......'similar' to what a loud sound might have on your eardrums...

We only really call it a Bang because it expanded outward. That's proven fact, even if the exact origin of the Universe is still disputed.

If you had such a time machine, by the way, you'd have to determine the exact spot that the Big Bang took place and travel there, because if you go anywhere else you'd simply cease to exist because nothing would exist outside of the area that the Universe was.

 

[Blobbenstein]

Dark matter is actually made up of unimaginably huge numbers of teapots.

 

[K-II]

I would have gone with 'you'd be incinerated like an ant in the path of a supernova'. Or at least I think so. Wasn't there a lot of matter/antimatter in the process of beginning to exist and immediately destroying itself about then?

 

[FortyTwo]

Dark matter is actually made up of unimaginably huge numbers of teapots.

http://en.wikipedia.org/wiki/Russell's_teapot

I would have gone with 'you'd be incinerated like an ant in the path of a supernova'. Or at least I think so. Wasn't there a lot of matter/antimatter in the process of beginning to exist and immediately destroying itself about then?

Well space was stealing from negative space and that didn't make nature too happy. Granted that is one of the few concrete truths about the cosmos that we know, but it probably wasn't very nice to be around when it first started happening.

 

[K-II]

We only really call it a Bang because it expanded outward. That's proven fact, even if the exact origin of the Universe is still disputed.

If you had such a time machine, by the way, you'd have to determine the exact spot that the Big Bang took place and travel there, because if you go anywhere else you'd simply cease to exist because nothing would exist outside of the area that the Universe was.

Wouldn't you be in it wherever you tried to go? It would be interesting to break out though, assuming there is an out. I wonder if anything would be perceivable, or if it would just be a (real, absolute) vacuum...

 

[FortyTwo]

Wouldn't you be in it wherever you tried to go? It would be interesting to break out though, assuming there is an out. I wonder if anything would be perceivable, or if it would just be a (real, absolute) vacuum...

I honestly think that you'd either be transported to a part of the Universe that actually existed, possibly a corresponding spot before everything went to **** (you'd be condensed into a point smaller than a quark but that's hardly a concern in a potential reality where we can simply step back in time unharmed to the moment of Creation), or you'd simply cease to exist because you're in a place that really doesn't exist so you can't either.

 

[K-II]

I don't think that really counts as transportation. More like making marks on a balloon and then inflating it. They're still in the same place on the balloon (or universe).

Is it even possible to cease to exist (as in, entirely, rather than being unobservable or changing to another form)?