T=gs?

[allo4]

please tell me why this is wrong or if it could work with tweaking??

If time travels relative to gravity so on earth it's one second per second but in space it travels faster and on a larger mass than the earth (say the sun) it goes slower then on earth time goes at one second per earth second where as say you gain 10 seconds in space a year and a year is 31536000 seconds then the relative time in space is 1.00000003 seconds per earth second in space(probably some dodgy maths but you get the idea) and I'll just make up that relative time on the sun is 0.5 seconds per earth second have we got an equation for this yet.

I guess that it is time relative to mass or gravity so:

relative time = mass or gravity in relation to time and probably a constant

 

I like to think that when all the mass of this universe was together at the start of the big bang or before although there wasn't really mass then the speed of time was 0 seconds per earth second.

 

I imagine relative time works exponentially compared to mass/gravity or the opposite to exponentially so the mass/gravity gets exponentially smaller in growth in comparison to the slower the speed of a second.

 

I'm hoping that it is the opposite to exponentially so eventually the mass gets to a size and any increase is almost irrelevant. (any decrease in the speed of time)

 

so eventually you could work out the total mass of the universe.

Lots of things to work out with this theory and lots of problems. it's probably relative to gravity not mass so you would work out the gravity a speed of time = 0

also this is ignoring anti matter and gravity

and presuming that at the big bang time was 0seconds per earth second

also lots of other problems too. any thoughts??

[allo4]

hmm I'm as pickled trying to read this as I was trying to think about it and put it into words. hopefully you can make sense of it.

also I was just thinking that g is an acceleration or what not so m/s2 yeah this is all obvious ahh pickled

[modest]

please tell me why this is wrong or if it could work with tweaking??

 

will do my level best :)

 

If time travels relative to gravity so on earth it's one second per second but in space it travels faster and on a larger mass than the earth (say the sun) it goes slower then on earth time goes at one second per earth second where as say you gain 10 seconds in space a year and a year is 31536000 seconds then the relative time in space is 1.00000003 seconds per earth second in space(probably some dodgy maths but you get the idea) and I'll just make up that relative time on the sun is 0.5 seconds per earth second have we got an equation for this yet.

 

I guess that it is time relative to mass or gravity so:

relative time = mass or gravity in relation to time and probably a constant

 

It's important to remember that gravitational time dilation is something that happens between two clocks... like, one clock runs .8 times the speed of another clock. So, the equation will always have a time term on each side of the equation because clocks are being compared. That said, the equation is:

 

[math]dt' = dt \left(1 + \frac{\Delta \Phi}{c^2} \right)[/math]

 

where [math]dt'[/math] is the change in time of the first clock, dt is the change of the second clock, [math]\Delta \Phi[/math] is the difference in gravitational potential between the two clocks, and c is the speed of light. Where we're talking about clocks at a certain distance from a single mass gravitational potential is given by:

 

[math]- \frac{GM}{r}[/math]

 

where G is the gravitational constant, M is mass, and r is the distance to the center of the mass.

 

 

I like to think that when all the mass of this universe was together at the start of the big bang or before although there wasn't really mass then the speed of time was 0 seconds per earth second.

 

I'm not sure it makes sense to me to say that time used to be slower or faster. I wouldn't know how to compare the speed of a clock yesterday (or billions of years ago) to the speed of the same clock today. I mean... if all of the clocks in the universe were slower yesterday than they are today then how would we know? It would seem like yesterday was a normal day.

 

so eventually you could work out the total mass of the universe.

Lots of things to work out with this theory and lots of problems. it's probably relative to gravity not mass so you would work out the gravity a speed of time = 0

 

Well, the difference in rates between clocks is proportional to the difference in gravitational potential between the clocks. The total mass of the universe really doesn't tell you how fast a clock runs. What matters is the difference in potential between two clocks in the universe.

 

If the universe were filled with a perfectly homogeneous fluid, for example, then all the clocks in that fluid would run the same rate no matter how dense the fluid was nor how massive all of the fluid is. What matters is the density of fluid near the first clock and the density near the second clock. If the density is the same (homogeneous) then the two clocks will run the same rate. If the density is different at the two different places then they will run at different rates.

 

and presuming that at the big bang time was 0seconds per earth second

 

I think I understand, but I'm just not sure how much sense it makes to say that 1 second 13 billion years ago is equal to 10 seconds today. I mean... how would you measure it? Think of an easier example, if 10 seconds yesterday equaled 60 seconds today then how would I measure that? What procedure would determine the difference in rates of clocks between yesterday and today?

 

It is a very thought-provoking and a good question

 

~modest

[emacneille]

I'll just make up that relative time on the sun is 0.5 seconds per earth second

one clock runs .8 times the speed of another clock

 

Does this mean that a sun or centers of high gravity are actually aging more slowly than us for a given unit of time from any perspective? I really don't get this.

 

Is the following accurate:

 

-two planets with intelligent life, one on a planet moving relatively much faster than the other. Might one civilization be in the stone age while the other has light bulbs due to time dilation?

 

if so, will the effect be visible over great distances? In my last statement I referenced simultaneity, which I know in relativity can never be agreed upon.

[modest]

Does this mean that a sun or centers of high gravity are actually aging more slowly than us for a given unit of time from any perspective? I really don't get this.

 

Yes, from any perspective a clock closer to a massive body will run slower than an identical clock further from a massive body because of gravitational time dilation. For example, a clock on the surface of the earth (call this clock A) ticks 45 microseconds less per day than a GPS clock in orbit (call the GPS clock B ) due to gravitational time dilation.

 

From the perspective of A, B runs fast. From the perspective of B, A runs slow.

 

Is the following accurate:

 

-two planets with intelligent life, one on a planet moving relatively much faster than the other. Might one civilization be in the stone age while the other has light bulbs due to time dilation?

 

Not quite. Gravitational time dilation is not symmetrical which is why the one clock is faster than the other from any perspective. Velocity time dilation, however, is symmetrical. This means that one planet, A, considers itself at rest while B has a relative velocity and is time dilated from A's perspective (its clocks run slow from the perspective of A). The other planet, B, considers itself at rest while A has a relative velocity and is time dilated from B's perspective (its clocks run slow from the perspective of B ).

 

If the planets are moving at 0.6c relative to one another then from the perspective of A, the clocks on A will advance 100 years while the clocks on B will advance 80 years. From the perspective of B, the clocks on B will advance 100 years while the clocks on A advance 80 years.

 

if so, will the effect be visible over great distances?

 

over any distance. We observe supernova, for example, which are very far away and moving very fast relative to us and we notice that they last longer than they would if they did not have a high velocity.

 

In my last statement I referenced simultaneity, which I know in relativity can never be agreed upon.

 

True, simultaneity is relative

 

~modest

[allo4]

like I said all of this is based on the idea that the huge mass of the universe combined makes time not move. probably a silly idea but basically saying that there was no time before the big bang and as the big bang started up time speed increased.

 

 

so not saying 100 years ago time was a little slower.. saying at the T=0 the speed of T=0(a 0degrees kelvin for time) then plug that into equation to work out the mass of the universe.

[modest]

like I said all of this is based on the idea that the huge mass of the universe combined makes time not move. probably a silly idea but basically saying that there was no time before the big bang and as the big bang started up time speed increased.

 

Right, I understand, and I don't think it is a silly idea.

 

The main issue I have is that you say "makes time not move", but that is not itself a complete or a sufficient concept. One must specify relative to what time is not moving. The statements "time speeds up", "time slows down", and "time does not move" only make sense if we say "relative to X, time speeds up, slows down, or does not move".

 

In other words, talking about the rate of a clock can't make sense unless we talk about the rate of a clock relative to another clock. Every clock, after all, advances one second per second relative to itself. It can't speed up or slow down intrinsically—it has to speed up or slow down (or stop) relative to another clock. If I say "time stopped for three minutes", what I'm really saying is that me, my clock, and my local time stopped while another clock—somewhere else—kept advancing for three minutes.

 

I hope I'm making clear and not confusing.

 

so not saying 100 years ago time was a little slower.. saying at the T=0 the speed of T=0(a 0degrees kelvin for time) then plug that into equation to work out the mass of the universe.

 

Right, but there is no equation that directly relates time to mass. There is no equation of the form T = c•M where T is the rate of a clock or the duration of an event, c is a constant, and M is mass or the strength of the local gravitational field. All of relativity's equations are like T1 = T2•c•M where T1 and T2 are two different clocks (or the duration of two different events). So, it's not that I'm being picky—I really don't see any way to answer the equation.

 

The idea that the rate of time everywhere in the universe can stop, speed up, or slow down seems inconsistent with relativity to me. All relativity will say is that time in one part of the universe can stop, speed up, or slow down relative to another part of the universe. A "rate of time" is defined as T1/T2. It is a ratio or comparison between two times.

 

~modest

[allo4]

yeah I was wondering if there was a way to make an equation that links time to mass

so i guess the perception of time from deep space (so it cant go any faster) watching something stop in all the gravity in the universe. like watching something go into a black hole getting slower and slower but on a bigger scale so it stops.

I just thought it would be a nice thought that if you combined all the galaxies in our universe it might be the perfect effect on time to make time stop. thus there is probably a way to work out the combined mass or gravity of all the galaxies if that idea was true.

but obviously like i said anti matter and anti gravity and such would probably make this idea not work

[modest]

yeah I was wondering if there was a way to make an equation that links time to mass

so i guess the perception of time from deep space (so it cant go any faster) watching something stop in all the gravity in the universe.

 

Ok, if the reference clock is outside of the influence of gravity (this is usually called coordinate time) then the equation is:

 

[math]T_P = T_0 \sqrt{1 - \frac{2GM}{rc^2}}[/math]

 

where [math]T_P[/math] is the proper time for a clock in the gravitational field a distance [math]r[/math] from the center of the mass, [math]M[/math]. [math]T_0[/math] is coordinate time outside the gravitational field, [math]G[/math] is the gravitational constant, and [math]c[/math] is the speed of light.

 

like watching something go into a black hole getting slower and slower but on a bigger scale so it stops.

 

Time does stop with a black hole of any size (or mass) from the perspective of an outside observer. If an observer far away from a black hole watches a clock drop into the hole they will notice the clock stop, being infinitely dilated, at the event horizon. For example, if the sun were compressed into a black hole it would collapse into a singularity. Afterwords, any clock that approached 2.9 kilometers distance from the singularity would stop in time from the perspective of an outside observer. The larger the mass of the black hole, the larger the hole, and the further the distance from the singularity to the event horizon.

 

I just thought it would be a nice thought that if you combined all the galaxies in our universe it might be the perfect effect on time to make time stop. thus there is probably a way to work out the combined mass or gravity of all the galaxies if that idea was true.

 

I see.

 

Pretty much any amount of mass, if it is compressed small enough, can make time stop from the perspective of an outside observer. The earth, for example, if it were to be compressed smaller than about 2 centimeters in diameter would form a black hole which would dilate time infinitely at the event horizon.

 

A galaxy would make a black hole with a radius around 0.1 lightyears. The mass of the visible universe makes a black hole with a radius around 15 billion lightyears.

 

Craig has worked out these numbers before, so I'll quote his post:

Here are a few numbers I calculated to get an intuitive sense of this.

 

Body describes a typical object of mass M, “M SM” means “million solar masses”, R is the radius of its event horizon, F the tidal force (tension) experienced by a 1 meter cable connecting a pair of 50 kg bodies (my idealization of a human body), and D the average density within a sphere of radius R.

Body                      M (kg)  R (m)     F (N)     D (kg/m^3)

Planet                      1e25  1.48e-2   1.52e20   7.33e29

Star                        1e31  1.48e4    2.05e10   7.33e17

Globular Cluster (5M SM)    1e37  1.48e10   2.05e-2   7.33e5

40 M SM                     8e37  1.19e11   3.20e-4   1.15e4

50 M SM                     1e38  1.48e11   2.05e-4   7.33e3

130M SM                   2.6e38  3.85e11   3.03e-5   1.08e3

                           8e39  1.19e13   3.20e-8   1.15e0

Galaxy                      1e42  1.48e15   2.05e-12  7.33e-5

Universe                    1e53  1.48e26   ~1e-34    7.33e-27

Note that in the vicinity of 40 million solar masses, average density is about the same as water, while at about 8e39 ([math]8 times 10^{39}[/math]) kg, average density is about the same as sea level Earth atmosphere. For a galaxy-mass black hole, the density can approach a “soft” vacuum, while for a universe-mass one, the density is about 4 hydrogen atoms / m^3 – a very “hard” vacuum.

 

cool stuff :)

 

but obviously like i said anti matter and anti gravity and such would probably make this idea not work

 

Antimatter is gravitationally attractive, so it works to dilate time like matter. The cosmological constant may be what you mean by anti-gravity. It is, indeed, a complication to the idea of a universe-sized black hole.

 

But... yeah, just to summarize: I take it you are wondering if all the mass of the universe compressed small enough would be enough to stop time from the perspective of an outside observer. The answer is that pretty much any amount of mass compressed small enough will accomplish this.

 

~modest

[allo4]

Cool thanks very much that answers it. I did say at the start I wanted to be told why it was wrong.

I probably should have known that at the event horizon that is where perspective of time stops. (If that is true)

I don't know that much about science which you have probably gathered it was just a thought that popped into my head and I wanted to find out if it was wrong.

 

So to carry on, after the event horizon (towards the center of the black hole) would the time perceived (obviously not seen) from space go backwards?

If so could the center of the black hole be at the time of the big bang .. the singularity

and again if so as time passes could the black hole get bigger just due to time? (so the event horizon moves further from the center of the black hole by the black hole effectively eating time.)

so the time slows down to the event horizon then goes backwards 13billion years to the center but in a billion years the time goes back 14 billion years from the event horizon the the center of the black hole.

 

sorry am I right in thinking the center of a black hole is also called the singularity the same as the big bang and is that why its called that too?

 

sorry like I said lack of knowledge and I just want to find out why this isn't right. I hope it is an interesting thought though

[emacneille]

Not quite. Gravitational time dilation is not symmetrical which is why the one clock is faster than the other from any perspective. Velocity time dilation, however, is symmetrical. This means that one planet, A, considers itself at rest while B has a relative velocity and is time dilated from A's perspective (its clocks run slow from the perspective of A). The other planet, B, considers itself at rest while A has a relative velocity and is time dilated from B's perspective (its clocks run slow from the perspective of B ).

 

If the planets are moving at 0.6c relative to one another then from the perspective of A, the clocks on A will advance 100 years while the clocks on B will advance 80 years. From the perspective of B, the clocks on B will advance 100 years while the clocks on A advance 80 years.

 

Is relative motion time dilation truly symmetric? Couldn't everything be tracked relative to a stationary center of the universe, or even better relative to the speed of the expansion of space? The latter would work as follows: Does the perspective of a viewer in which both planets are moving away equally fast encounter more freshly made space in one direction than any other?

 

After all even if the motion two planets seems symmetric to both parties one must have more momentum, and be traveling closer to the speed of light. Therefore time and functions of it such as entropy would go more slowly for the planet that is truly moving faster.

 

And I also wonder allo's questions