A Universe without Time

[asprung]

Motion cannot take place without time. It should thus be clear that the big bang and the evolution of the universe could not have taken place without time. Time must thus be coinsided as an essential element of the universe.

 

Time has traditionally been expressed in terms of units read out by instruments used to measure it – seconds, minutes etc. Its underlying nature has appeared to escape a good definition. Time as I see it is the force that maintains the present i.e. “now”. I propose that it marches on or progresses at a uniform rate from the big bang constituting a universal time and ageing of the universe. This universal time cannot be read by clocks which may run at different rates in different time frames. The length of a body decreases in the direction of its velocity irrespective of its composition and it may be that the rate of clock decreases in the same manner irrespective of its construction. The different reading of clocks in different time frames may be caused by such difference in the clock rate as opposed to a difference in what is being measured.

I would welcome suggestions as to how this universal time might be measured.. It may be that it has some relationship to the speed of light. It must be fast enough so that light cannot run ahead into the future or may put a brake on lights’ speed for the same reason.

The presence of universal time would appear to be evidenced by parties in different time frames being able to view an event as it occurs though their clocks read vastly different times and by their being able to come together in the same present.

[Sisyphus]

"Clocks" means all indications of the passing of time, including the speed of light and your own subjective experiences. There is no such thing as "absolute time" in the sense you want. Also, events which are simultaneous in one reference frame are not in another.

[swansont]

The length of a body decreases in the direction of its velocity irrespective of its composition and it may be that the rate of clock decreases in the same manner irrespective of its construction. The different reading of clocks in different time frames may be caused by such difference in the clock rate as opposed to a difference in what is being measured.

 

But the evidence is that it's not dependent on the type of clock. Both nuclear and atomic processes, with different coupling constants, give consistent results.

[north]

Motion cannot take place without time.

 

of course motion can

 

its more like without motion of objects, by objects , there is no way to measure time

 

because without the objects movement there is no fundamental basis on which time can be derived

[asprung]

Without time everything would be frozen and there could be no motion.

I was proposing that the slowing would effect any type of clock including those you mention.

[granpa]

without ftl communication it cant be measured. entanglement may or may not provide ftl communication.

[NowThatWeKnow]

without ftl communication it cant be measured. entanglement may or may not provide ftl communication.

 

What is "ftl"? Just because something can not be measured does not mean it doesn't exist.

[iNow]

FTL = Faster Than Light.

[Sisyphus]

 

of course motion can

 

its more like without motion of objects, by objects , there is no way to measure time

 

because without the objects movement there is no fundamental basis on which time can be derived

 

Without time, there can't be motion, by definition. Motion = change of position over time.

[gre]

I don't think matter or space can exist without time either. Can anything exist without it? .. Time is probably the most fundamental aspect of the universe..

[NowThatWeKnow]

...Time as I see it is the force that maintains the present i.e. “now”. I propose that it marches on or progresses at a uniform rate from the big bang constituting a universal time and ageing of the universe. This universal time cannot be read by clocks which may run at different rates in different time frames

 

...I would welcome suggestions as to how this universal time might be measured...

 

Have you read the thread "is spacetime absolute?" where Martin and I discussed universal time?

http://www.scienceforums.net/forum/showthread.php?t=40033

 

With today's technology universal time, not to be confused with absolute time that does not exist, is in most cases an abstract thought experiment at best. What martin suggested is a universal time using a clock at rest with the CMB and in the absence of gravity. Any location could then adjust their clock for movement and gravity to have a synchronized clock with universal time. It would move at a different rate then local time clocks but that is ok. You would still have two locations or frames that had synchronized clocks and could share the same "now".

 

Because of continous movement in the cosmos, you would almost need an automatic gravity meter and CMB speedometer attached to an atomic clock for it to work. Maybe someday in the future this will be possible. Today's technology has allowed us to adjust the clocks on the GPS satilites for SR and GR so we can have a universal "now" in different frames.

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FTL = Faster Than Light.

[asprung]

The concept of the present or “now’ proceeding uniformly throughout the universe would appear valid and could constitute universal or absolute time depending on definition. Measuring it would appear to be a very complicated matter.

I view the difference of time in different time frames to be caused by different clock rates. The compression of length by velocity should cause an increase in density or molecular concentration which could cause a slowing of any “clock”.

[NowThatWeKnow]

I view the difference of time in different time frames to be caused by different clock rates. The compression of length by velocity should cause an increase in density or molecular concentration which could cause a slowing of any “clock”.

 

I can not think of anything that could not be used as a "clock", even if the rate of decay is used to measure time. I would also use caution when comparing absolute and universal time to each other.

[fireblast_12]

Time is the basis of everything since it is everything. Everything takes time to move and all the molecules in an object are always moving, so everything is basically time.

[swansont]

The concept of the present or “now’ proceeding uniformly throughout the universe would appear valid and could constitute universal or absolute time depending on definition. Measuring it would appear to be a very complicated matter.

I view the difference of time in different time frames to be caused by different clock rates. The compression of length by velocity should cause an increase in density or molecular concentration which could cause a slowing of any “clock”.

 

Why is it predictable and not dependent on the density in other ways? Why does it change with gravitational potential? Density changes with the acceleration, not the potential.

[GDG]

The concept of the present or “now’ proceeding uniformly throughout the universe would appear valid and could constitute universal or absolute time depending on definition. Measuring it would appear to be a very complicated matter.

 

Only if you ignore Relativity. You're trying to set up a universal preferred reference frame: Relativity proves that you cannot.

[Martin]

Only if you ignore Relativity. You're trying to set up a universal preferred reference frame: Relativity proves that you cannot.

I agree that it is impossible to set up a universal reference frame, in the sense of rectilinear coordinates, flat non-expanding space, and so forth.

A reference frame in the stye of 1905 special relativity could hardly be global.

 

I haven't studied what asprung is saying. For all I know he is wrong about some things. But is he really trying to set up a global reference frame?

 

Maybe all he wants is a universal time coordinate, a natural slicing of spacetime into spatial slices, a natural notion of global simultaneity etc. Those things are routine in cosmology, so they are certainly not ruled out by the basic GR theory!

 

Indeed they are built in to the standard Friedman model that everybody uses in cosmology.

 

You are citing wikipedia on special relativity. This is the 1905 theory which has only limited applicability. It does not appy to the universe as a whole.

 

Special Rel was superseded in 1915 by general relativity. In GR you can have solutions---like those used in cosmology---which have a global time coordinate.

 

Relativity does not preclude a universal time coordinate, a natural slicing of the entire spacetime into spatial slices, a natural notion of global simultaneity etc. These things can be properties of particular solutions of the general theory. I'm talking not about a "frame" (not the appropriate term here) but about a foliation, or slicing.

 

I think we should be careful about talking about a global reference "frame", because frame is basically a local concept. "Global frame" is somewhat of a contradiction in terms.

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I would welcome suggestions as to how this universal time might be measured..

 

Asprung, there are several ways that universal time can be measured, but they aren't very precise. They are based on the standard model of the universe used in cosmology (that is the context where expressions like "universe time" and "Friedman time" come up).

 

I'm not sure I understand what you are driving at in your thread, it sounds kind of philosophical to me. If I understood I might or might not be sympathetic, might or might not be interested. Can't tell.

 

But if we just want to look at the simple question of how do you measure Friedman time? That's easy. Anywhere in the universe, any observer as long as he is not too far down a gravity hole, and approx at rest relative to the Background, should measure the same age of the universe.

 

That's all it is. Absolute time is time since the start of expansion. Or you can date things from the emission of the Background photons (which came some 380,000 years later.) You get it with these two equations (using a programmed calculator):

http://en.wikipedia.org/wiki/Friedmann_equations

 

These are built into various online calculators, like this:

http://www.astro.ucla.edu/~wright/CosmoCalc.html

 

So you don't have to work directly with the equations (i.e. with the equation form of the model.)

 

All you need is to type two numbers (to wright's calculator for instance) and press "flat". It will tell you the age since start. That's your time teller, and anybody anywhere in the universe can do the same thing.

 

We could make a much simpler online calculator that would do it. Wright's calculator is meant to serve a lot of different needs so it looks complicated. What we are using it for here is very elementary.

 

Ignore all the other stuff on the calculator. The two numbers you put in are hubble parameter and matter density---in Wright's notation H₀ and Omega_M. They are at the top left. They are the first two boxes where you could put in a number!

 

Let's say it is a few billion years in the future and H has gone down to 65 and matter density is down to 0.13

put those into the calculator and press "flat" and what do you get?

 

I get 18 billion years.

 

Now, any alien anywhere in the universe can look at the sky and see that H₀ is 71 and Omega_M is 0.27. If you make sure those two numbers are in, you press flat and you get 13.7 billion years. That is the time now. Any alien anywhere, who wants to know the time, can read it right now from the sky in exactly this way: 13.7 billion years. His calculator might work in different units, different years, but no essential difference.

 

I'm being pretty loose numerically. Maybe I should make this more precise--but that could be in another thread. In the meantime, does that address your question? You said uyou would welcome description of how to measure universe time.

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It's actually even simpler. You only have to make one measurement, measure one thing, and the model tells you the time. I just posted how that works in the "CosmoBasics" thread.

Edited May 2, 2009 by Martin
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[iNow]

I haven't studied what asprung is saying. For all I know he is wrong about some things. But is he really trying to set up a global reference frame?

 

Maybe all he wants is a universal time coordinate, a natural slicing of spacetime into spatial slices, a natural notion of global simultaneity etc.

I cannot be sure, Martin, but having read most of his posts here, I am relatively confident that asprung is after the exact opposite of spatial slices. His comments are an attempt to argue for a single solitary universal "now" which applies to everything, everywhere, regardless of acceleration or dilation effects.

 

In the strictest sense, he is arguing for a universal time, and that time is the present... and all observers regardless of reference frame (he argues) are sharing the exact same present.

 

That's my interpretation, anyhow. Cheerio.

[NowThatWeKnow]

In the strictest sense, he is arguing for a universal time, and that time is the present... and all observers regardless of reference frame (he argues) are sharing the exact same present.

 

That's my interpretation, anyhow. Cheerio.

 

Sometimes his wording does leave his thoughts open to different interpretations but I think you are pretty close. However, if we could have a synchronized clocks at any two locations, wouldn't that show we can be sharing the same present or "now"?

Edited May 2, 2009 by NowThatWeKnow

[asprung]

INow's interpertation is what I was getting at. Thanks. And this is so from the start of the Big Bang. And who knows from before.

[NowThatWeKnow]

INow's interpertation is what I was getting at. Thanks. And this is so from the start of the Big Bang. And who knows from before.

 

So, does Martin's universal clock satisfy you as far as the present and "now"?

[GDG]

I agree that it is impossible to set up a universal reference frame, in the sense of rectilinear coordinates, flat non-expanding space, and so forth.

A reference frame in the stye of 1905 special relativity could hardly be global.

 

I haven't studied what asprung is saying. For all I know he is wrong about some things. But is he really trying to set up a global reference frame?

 

Maybe all he wants is a universal time coordinate, a natural slicing of spacetime into spatial slices, a natural notion of global simultaneity etc. Those things are routine in cosmology, so they are certainly not ruled out by the basic GR theory!

 

Indeed they are built in to the standard Friedman model that everybody uses in cosmology.

 

You are citing wikipedia on special relativity. This is the 1905 theory which has only limited applicability. It does not appy to the universe as a whole.

 

Special Rel was superseded in 1915 by general relativity. In GR you can have solutions---like those used in cosmology---which have a global time coordinate.

 

Relativity does not preclude a universal time coordinate, a natural slicing of the entire spacetime into spatial slices, a natural notion of global simultaneity etc. These things can be properties of particular solutions of the general theory. I'm talking not about a "frame" (not the appropriate term here) but about a foliation, or slicing.

 

I think we should be careful about talking about a global reference "frame", because frame is basically a local concept. "Global frame" is somewhat of a contradiction in terms.

 

I'm not an expert in physics, but I thought that special rel was not invalidated by general rel, only expanded. My recollection of special rel is that it shows that events that are simultaneous in one reference frame may not be simultaneous in a different reference frame; thus, one cannot define a preferred reference frame. If one cannot establish simultaneity, I don't see how one can establish a universal time coordinate.

 

Never had general rel: does it undo everything that special rel proved?

[Martin]

...My recollection of special rel is that it shows that events that are simultaneous in one reference frame may not be simultaneous in a different reference frame...

 

Quite true!

 

thus, one cannot define a preferred reference frame.

 

Where do you get the "thus"? Of course one can define a preferred reference frame, simply by preferring it if there is some good some reason.

 

thought that special rel was not invalidated by general rel, only expanded.

 

Absolutely true! Mathematically speaking I would say in fact that GR validates SR, because it reveals why SR works so well. SR is the flat solution to the GR equation that you get when there is no matter in the universe to curve it, and no expansion. SR is one of the solutions of GR, one of the special cases. One can say that because GR is true therefore SR (the minkowski metric) must work as a good approximation in small enough neighborhoods where the matter density is low enough.

 

Globally, the SR (or minkowski) metric describes a universe with no matter in it (no curvature, no gravity) but it works locally as an excellent approximation in low matter density, like where we are (for practical purposes even a solid brick is low density, you need something much denser to cause noticeable curvature at small scale.

 

SR is fine and consistent with GR to a good approximation. GR is more basic, it underlies SR----provides a reason why geometry is the way it is.

 

I think where you get into trouble is where you try to make SR say things it really doesn't say. GR deals with a more complicated world, with matter in it and in GR there can be reasons to prefer a coordinate system. And you can have other solutions to the GR equation which are not the particular SR solution called "minkowski space".

 

One way to say it is that not all solutions to GR are "minkowski space"*. Not all metrics are the minkowski metric which is used in SR and which is basic to SR.

 

*Globally I mean, all solutions look like minkowski space approximately in a small neighborhood---SR always applies locally.

 

Never had general rel: does it undo everything that special rel proved?

 

As far as I know GR does not undo anything that SR actually proved. SR is one possible solution of the GR equation, but it should always be thought of as a special case.

There are other solutions, other metrics, other geometries, that solve the GR equation (like Friedman universe, de Sitter universe) which would contradict what people may mistakenly suppose that SR proved.

 

Like this thing about not being able to have a preferred time coordinate or preferred spatial slices. SR never proved you couldnt prefer some particular frame if there was a good reason to prefer it.

 

Of course people using the unpreferred frame see different simultaneity---they slice spacetime differently---that's their lookout.

Does this make things any clearer for you?

Edited May 3, 2009 by Martin

[swansont]

I'm not an expert in physics, but I thought that special rel was not invalidated by general rel, only expanded. My recollection of special rel is that it shows that events that are simultaneous in one reference frame may not be simultaneous in a different reference frame; thus, one cannot define a preferred reference frame. If one cannot establish simultaneity, I don't see how one can establish a universal time coordinate.

 

It's not that you can't define a preferred reference frame. It's that measurement, i.e. the application of physics, will not define one for you — nature will not prefer one over the rest. IOW, if you are in an enclosed space, there is no local experiment you can do that will tell you if you are moving or at rest with respect to a particular frame. We choose convenient reference frames all the time.

[asprung]

I propose that events are simultaneous in all referense planes - "now" -only the clocks may run at diffrent rates. If not how could a party in any refrence plane come together with a party from any other refrence plane?