Universe, Distance and Time

Can a simple formula like Distance = Velocity * Time , be the key to the theories of the Universe ? People say that the Universe is expanding, this means that the distance from the Centre of the Universe is continually increasing. Distance is directly proportional to Time, doesn't that mean that as the distance from the centre of the Universe increases ( or as the Universe expands) , time increases or progresses. Does this not imply that time is simply the result of the steady expansion of the Universe ? Will this mean that if the Universe were to stop expanding, time would stop. But again there is a catch, because it means that the Universe is doing something and time is responding afterwards, which is impossible because we all know that if something happens, that means time is passing. Maybe here is where Tachyon particles come to play ( Tachyons are particles that move faster than light) , the Tachyon particles may be making it possible for an action of the Universe to happen before time responds o it.


I'm sorry if I lost you over there ( these are purely the thoughts of a crazy 15 year old )

Please feel free to Criticise me ! Call me Crazy
But please Reply with your thoughts

Siddharth.A

[edit on 22-4-2005 by siddharthsma]

You know I've read both "A brief history of time" by Stephen Hawkins and "The elegant universe" by Brian Green (I highly recommend them) and I have a science background, but I can never quite get my head around the whole space (distance), time, speed of light barrier stuff.

Good questions though. I'll move this over to the science and technology forum. Maybe someone there can help.
.

There is a formula for the rate at which galaxies and everything else for that matter are moving away from us, it is called hubbles law:

V=D.h where h is hubbles constant, D is distance and V is velocity. Now since V=d/t (where V is velocity, d is distance and t is time) we can derive a further expression: d/D.h=t , now as u can see the d's cancel out which leaves us with 1/h=t or the reciprocal of the hubble constant equals time this can also be expressed as 1/t=h. I find it very hard to visualise what the maths is actually saying.

In short as time increases then hubbles constant must decease and this means that the rate at which the universe is moving away from us must also decrease because that is what hubbles constant represents. This means that as the universe gets older and thus time increases the rate of expansion must slow, at the begining of the universe time would have been very close to zero which means the rate of expansion of the universe must have been near infinite.
I hope this explains your question, time is indeed related to the expnasion of the universe.

[edit on 23-4-2005 by ufo3]

Originally posted by ufo3
This means that as the universe gets older and thus time increases the rate of expansion must slow, at the begining of the universe time would have been very close to zero which means the rate of expansion of the universe must have been near infinite.
[edit on 23-4-2005 by ufo3]

But isn't the universe expanding at an increasing rate? The increase in rate of expansion is not slowing, its getting faster

I know, it seems very contradictory but some think that the universe will eventually end in a big crunch where it will start to contract again.

Originally posted by siddharthsma
... Distance is directly proportional to Time, doesn't that mean that as the distance from the centre of the Universe increases ( or as the Universe expands) , time increases or progresses. Does this not imply that time is simply the result of the steady expansion of the Universe ?

Well, what you say is true but you are applying Newtonian mechanics to the universe, which you cannot do.
D=s*T this is true in the case of bodies in one inertial frame but in the case of the universe this formula cannot be applied so simply. When we say that distance is directly proportional to time it is wrt to constant velocity, as we all know, so as the universe expands with a constant velocity time increases. This is not to say that time would cease to continue if the universe were to stop expanding, but as time increases the universe expands proportionately.
But this cannot be applied to the universe as the universe does not expand with uniform velocity or at a constant rate through out the universe, it is speculated that the rate of expansion of the universe is increasing continuously i.e. velocity changes with time.
Even if you could apply the above Newtonian law, you should imagine this scenario: Imagine if you apply a force on a ball and it moves at constant velocity i.e. zero acceleration then the distance traveled by the ball would be directly proportional to the time taken, conversely if the time taken by the ball would depend on the distance covered i.e. for say 10sec a span of 20 feet and 11th sec 20.5feet and so on. You cannot say that the time on your watch is a result of the motion of the ball only (the reason I say only I will explain later) and no motion of the ball would mean no time can you??
A similar thing applies to the universe in general.

Originally posted by siddharthsma
Will this mean that if the Universe were to stop expanding, time would stop. But again there is a catch, because it means that the Universe is doing something and time is responding afterwards, which is impossible because we all know that if something happens, that means time is passing.

Time is known as the measurement of flow basically. As long as the universe observes flow in the system we say that time passes. If the universe were to stop 'flowing' then time would stop! Expansion of the universe is only one contributor to the total flow of the universe as a whole.
Flow is basically movement of atoms, electrons, energy etc. If every single particle in the universe were to stop and if all energy was to suddenly freeze then we would attain zero flow - which would result in the stoppage of time as we know it but we would not be able to tell the difference as we would be in suspended animation ourselves, time could have stopped many times and we wouldn't have known about it at all. (That’s why I said 'only' earlier).
So even if the universe were to stop expanding time would still carry on but albeit a bit slower than before but we won't be able to notice it as we are part of the same frame of reference. Now time and matter ( I don' t know if this part is correct ) I think have a spontaneous relation i.e. time and flow are related instantaneously as time changes flow changes too or so on I think.
Tachyons are particles that have not been accepted to exist even theoretically, they are speculated to exist and their relation to the universe is not well known, I think they are particles of the multiverse and lie outside all other frames as follow the master sets laws while they exert influence on our frame.
I hope this is not very confusing and drawn out but this is very basic stuff which you could get from any good physics book (not my interpretations though! ) Try if you can read this.
www.amazon.com...

[edit on 23-4-2005 by IAF101]

Well, there is no center...the rate at which the universe is expanding is accelerating, which basically disproves a big crunch, and there is no evidence for tachyons.

That's about all I'll say. I'll elaborate if requested, I suppose.

There is no evidence of Tachyons. But Einstein must have had a reason to think of them.

If the acceleration is increasing that means eventually the velocity will reach the speed of light.

If nothing can travel faster than the speed of light then the acceleration would have to stop causing the velocity to become constant.

If the universes expansion is getting faster does that mean the universe is getting heavier? As Einsteins theory says objects get heavier as they approach the speed of light.

Forget my post above, i've done some reading:

The mass of the Universe is not increasing.
When we astronomers say that galaxies are moving away from us, and that the farther away from us they are the faster they are moving away, we mean that the space between them is expanding. The galaxies themselves are not actually moving through space at any very high speed. Rather, the space between the galaxies is expanding.
Space has no mass and has no restrictions on how fast or slow it can expand or contract.

Presumably in the far future the distances between galaxies will be so great that we won't be able to see any of them?

[edit on 23-4-2005 by nibiru]

It doesn't mean it's going to reach the speed of light. There are infinite numbers between 2.9e8m/s and 3e8m/s. Think of it like why the universe won't ever reach 0 K. It's not hard to imagine...

So if space has no mass and no restrictions, but it still has matter right? If so then that could prove much better than anything else right now that something can exist without mass.

Uhh, it's been known for a long time things exist without mass...like a photon.

If the acceleration is increasing that means eventually the velocity will reach the speed of light.

No, that's not correct. Anything can continue to accelerate and not reach a given value (as long as it's not already moving faster than that arbitrary value): it simply approaches it asymptotically. That is, the rate of acceleration decreases.

Originally posted by T_Jesus
Uhh, it's been known for a long time things exist without mass...like a photon.

I thought a photon had a miniscule mass..That is, enought to be effected by an extremely large mass. Gravitational lensing, would that not show that there is some mass, no matter how small, to a photon?
If not how would that effect be explained?

They are massless, but they have momentum.

And for lensing, don't forget they're not only described as a particle, but as a wave. I know, I know, we're all waves too, but the photoelectric effect got Einstein the Nobel, not relativity.

If photons and space have no mass but have momentum then
what bit has the momentum - nothing ?

If something has nothing then how can it expand what is expanding ?
Nothing from what i can make out ?

Confused

Space-time itself is expanding...think of it like blowing up a balloon.

OK but a ballon has mass ? right

So how can i think of it like that.

Like i said if it is expanding then what is Space-time ? whats that ?
please include some proof if you can -

Maybe the problem is with the discription expanding i dunno