talkmagic.co.uk

Wishmaster wrote:My head hurts now. If something isn't infinitely large and therefore has an end, there has to be something beyond. I can't compute what you said at all.

Yup. That's the point!

It's the same argument for the start of the universe; what was there before the Big Bang? There must have been something? And something must have "caused" the universe because everything has to have a cause doesn't it?

In fact, time is simply another dimension of the universe, so there was no "before"; the universe has a finite age and yet there was nothing before (the whole idea of "before time" relies on the existence of time, and time didn't exist). Cause and effect only have meaning if there is time and if that time is roughly linear.

I like this game. Thinking of things that are entirely beyond our capability to actually imagine.

nickj wrote:In fact, time is simply another dimension of the universe, so there was no "before"; the universe has a finite age and yet there was nothing before (the whole idea of "before time" relies on the existence of time, and time didn't exist). Cause and effect only have meaning if there is time and if that time is roughly linear.

I like this game. Thinking of things that are entirely beyond our capability to actually imagine.

On this note of barely comprehendable things, if time does exist (at least on a relative and not necessarily a quantum level), and the state that it exists as is a form of dimension then it should be possible to travel within that dimension if we could reasonably comprehend it (as in the example of a fourth dimension). If this were the case do you think time would then have a "visible" beginning and end much like physical space and therefore you would have the ability to not only travel within but also without of time.

Of course there is also the possibility that time does not exist (at least in the way we think) and it is merely our human interpreation of the environment we have no other way of perceiving...

Ok so Wormhole (aka Einstein Rosen Bridge) while theoretically possible also stretches what we understand about the very basics of space time.

Heck Einstein's relativity makes time a constant so that the future like the past exists and we are simply arching our way through it. Which is inconsistent with quantum mechanics so therefore while macro acceptable is micro wrong.

You could also postulate that if you could do zero molecular motion and let the universe expand past you (the very concept of warp btw) then you'd be traveling at the rate of expansion of the universe.

The reality is that the universes size is just travel prohibitive.

However as Carl Sagan wrote, "If we are the only life in the universe it is an awfully big waste of space."

Infinite wrote:However as Carl Sagan wrote, "If we are the only life in the universe it is an awfully big waste of space."

When they were trying to decide what to put on the gold disk mounted on the Voyager spacecraft, someone suggested a nice bit of Bach to show the level of musical accomplishment humans are capable of. Sagan objected, saying: "That would just be showing off!"

Infinite wrote:Heck Einstein's relativity makes time a constant so that the future like the past exists and we are simply arching our way through it. Which is inconsistent with quantum mechanics so therefore while macro acceptable is micro wrong.

You could also postulate that if you could do zero molecular motion and let the universe expand past you (the very concept of warp btw) then you'd be traveling at the rate of expansion of the universe.

Actually, we only experience time relative to others! The faster we travel, the less time we would experience relative to everyone slower, to the point that, if it were possible to get a massive body to travel at the speed of light (which would require infinite energy, so is impossible), it would appear that time stood still for us whilst rushing past at an infinite rate for everyone else; we would instantly get to the end of the universe.

By some clever mathematics, the equations of special and general relativity can generate all sorts of interesting scenarios, including wormholes and warp drives that work by compressing and expanding spacetime around the drive allowing the hypothetical ship to travel at speeds which are locally slow, but are much faster than the speed of light relative to the flat spacetime at a distance from them.

Also the idea of "Closed time-like curves" have been postulated, which are a fancy way of saying that the correct distribution of mass and energy could cause time to loop back on itself. I believe that this was actually achieved a few years ago sending a photon or an electron or something to jump forward or backward in time by a tiny fraction of a second (long enough to determine from its quantum state that it had actually travelled through time).

I'm only just good enough at maths to be able to follow these calculations, but they really are intriguing.

nickj wrote:Actually, we only experience time relative to others! The faster we travel, the less time we would experience relative to everyone slower, to the point that, if it were possible to get a massive body to travel at the speed of light (which would require infinite energy, so is impossible), it would appear that time stood still for us whilst rushing past at an infinite rate for everyone else; we would instantly get to the end of the universe.

Ah yes this is what I said you just said it better meanie.

nickj wrote:By some clever mathematics, the equations of special and general relativity can generate all sorts of interesting scenarios, including wormholes and warp drives that work by compressing and expanding spacetime around the drive allowing the hypothetical ship to travel at speeds which are locally slow, but are much faster than the speed of light relative to the flat spacetime at a distance from them.

Yes this is true however note that quantum time does not hold true to that statement. Time exists only as the forces of interaction occur. So you can't warp at the quantum level there is a fixed limit to how far out the collapsing wave reaches.

nickj wrote:Also the idea of "Closed time-like curves" have been postulated, which are a fancy way of saying that the correct distribution of mass and energy could cause time to loop back on itself. I believe that this was actually achieved a few years ago sending a photon or an electron or something to jump forward or backward in time by a tiny fraction of a second (long enough to determine from its quantum state that it had actually travelled through time).

Ah string theory... compressed density of matter causes the speed of light to be faster near strong gravity wells than from open space.

Yes they did manage to make a photon jump in time. It was a small light well that rotated very fast and caused the light to skip a measurable amount of space in to few amounts of time.

HOWEVER you can only travel within the confines of the vortex so ... unless you plan to create a gravity well that's 400 light years your still only traveling a few feet.

I was under the impression that photons do not have any time? They exist in a state of zero time because they cease to exist the moment they are created?

A_n_t wrote:I was under the impression that photons do not have any time? They exist in a state of zero time because they cease to exist the moment they are created?

Na Photons have time as WE define time. They do not have time in the sense that time is relative as NickJ pointed out.

A photon traveling at the speed of light (which it does because it is light) only sees the next step in its travel as one hop away. It itself is unaware of the long slow molasses type time we interact with on a common reference frame.

However to us the light moves at a constant speed. We can measure how fast that photon moves from one area to another and then determine how it relates to that constant. Hence why we can slow light down in water, plasma, etc.

What they did was cause a photon to move further than it should have been able too without quantum tunneling.

I had a nice dream about time recently that pretty much summed up the problem of having to use infinity in all our equations but I haven't had time to write it out.

Yeah, Quantum Relativity is still a work in progress!

An abstract I was looking at a while back commented on a tunnelling photon effectively travelling at 1.7c, though they stated that this was not a true signal velocity so Einstein causality was not violated.

Concerning travelling in a custom gravity well (or light well/energy well or whatever), theoretically, isn't it the case that the correct profile could allow travel forward or backward through time? My understanding was that they used pulsed lasers to create what was effectively a whirlpool in space/time and then shot a photon through it. As a result of the extreme curvature of the energy well, bits of space which would not normally "touch" formed a path that the photon could travel avoiding what would normally be intermediate space (sorry, I'm trying to write this in a way I actually understand!). If this is the case, and a well could be created which was well enough mapped, would it not be possible to map a course through it which would result in the particle exiting at any arbitrary point in space or time through which the vortex passed? i.e. sending the particle back to any time after that at which the vortex formed.

BTW, Infinity, are you a physicist by any chance?! I have an MPhys in Astrophysics but specialised in Exoplanetary studies for the masters element, so I sort of neglected relativity and QM a bit as can be seen from my complete lack of the appropriate vocab!

I love this subject, but every time I think I've begun to understand a little, it just sneaks away, quietly sniggering at me. It's the same feeling as having someone's name on the tip of your tongue.

Nah,

Well actually... nah. I was HIGHLY interested in it but in the end you have to be in the top 1% to do anything fun and when they closed down the LHC in Texas it was sort of like, "Well c*** (not the best)."

I did work at the Standford LAC and thus sat around with all these people and bantered about the nature of spacetime a great deal. I have a passion around time it borders on obsession with it.

So I too can run the math but I can't really interpret that complexity of the subtleties of the math.

We are still bound by as for your going backwards in time the quantum limitation of the certainty principle. You can shoot something backwards in time but you will never see it again. That time is different than this time and the quantum result does not interact with our time etc etc. The age old, for every choice there is a split in universes.

This is why they shot it forward rather than backwards because we'd have no idea if it ever got there or went somewhere else. Presuming we didn't see any energy conversion signatures to indicate it was annihilated.

All in all we are finding that Einsteins version of Space Time is more and more wrong about the "time" part.

For example in relativity it should be possible to stop all molecular motion (zero Kalvin) and time would cease to exist for it and anything attempting to interact with it.

Yet in that same theory you could predict as part of the time being a dimension when and where it would be at any point in its entire existence regardless if we can interact with it.

It doth make no sense man

Infinite wrote:All in all we are finding that Einsteins version of Space Time is more and more wrong about the "time" part.

For example in relativity it should be possible to stop all molecular motion (zero Kalvin) and time would cease to exist for it and anything attempting to interact with it.

Yet in that same theory you could predict as part of the time being a dimension when and where it would be at any point in its entire existence regardless if we can interact with it.

It doth make no sense man

Here, though, we are trying to talk quantum relativity again, and that doesn't work; my understanding is that relativity holds true in every scenario where quantum effects are negligible and is, in fact, one of the most tested theories out there. Once Quantum effects, particularly the uncertainty principle, are introduced it all goes out the window. This is one of the prime reasons for hunting for gravitons in the hope that, if they exist, there is some facet of their behaviour that will make a theory of quantum gravity viable and hence be able to tie general relativity to quantum theory and possibly then special relativity too.

As I said though, I am by no means an expert and really know very little at all about the particle physics side of the whole thing.

You know, we seem to have hijacked the aliens thread somewhat; sorry!

arent we all just constantly moving atoms too? and the reason why a knife can go through flesh is that the knife's atoms move faster than the flesh's?

happy to be completely wrong here, i read a "dummies guide to quantum pyshics" once...thats pretty much all i remember...

nickj wrote:

Infinite wrote:All in all we are finding that Einsteins version of Space Time is more and more wrong about the "time" part.

For example in relativity it should be possible to stop all molecular motion (zero Kalvin) and time would cease to exist for it and anything attempting to interact with it.

Yet in that same theory you could predict as part of the time being a dimension when and where it would be at any point in its entire existence regardless if we can interact with it.

It doth make no sense man

Here, though, we are trying to talk quantum relativity again, and that doesn't work; my understanding is that relativity holds true in every scenario where quantum effects are negligible and is, in fact, one of the most tested theories out there. Once Quantum effects, particularly the uncertainty principle, are introduced it all goes out the window. This is one of the prime reasons for hunting for gravitons in the hope that, if they exist, there is some facet of their behaviour that will make a theory of quantum gravity viable and hence be able to tie general relativity to quantum theory and possibly then special relativity too.

As I said though, I am by no means an expert and really know very little at all about the particle physics side of the whole thing.

You know, we seem to have hijacked the aliens thread somewhat; sorry!

I think the simplified version of this equates to something along the lines of;

General relativity holds true for anything big but is rubbish for anything small. Quantum Mechanics is rubbish for anything big but holds true for anything small.

The miraculous "Quantum Theory of General Relativity" should be an amalgamation of the two and is argued by some to be the "key to the universe", although history tells us that one key normally leads to another locked door.

=)

A_n_t wrote: although history tells us that one key normally leads to another locked door.

=)

Nah, we must have nearly solved it all this time!

I'm sure that as soon as any linking theory comes along there will be something discovered that doesn't fit. We probably aren't very close to a TOE yet.