Is Time's Speed Just Wild Speculation?

[monty37]

what is the speed of time?

 

[Hootenanny]

what is the speed of time?

Perhaps you could elaborate on your question?

 

[Naty1]

Time appears to pass at a constant rate and that was a cornerstone of Newton's theories. But Einstein showed that space and time are NOT fixed and immutable; they vary according to one's relative motion...space contracts and time slows as relative speed between observers increases. Identical events are observed to occur at different times in different frames. Time also slows down near massive gravitational bodies where gravitational potential is greater.

Check Wikipedia at http://en.wikipedia.org/wiki/Time#Modern_physics

for some additional description and further references.

 

[Dale]

Time is the thing measured by an ideal clock, and an ideal clock ticks at a rate of 1 second/light-second.

 

[Max™]

What is the speed of Left?

 

[negitron]

What is the speed of Left?

More accurately reflecting the OP: what is the speed of height? If you consider time as a dimension, it doesn't move at all; instead, objects move through the time dimension in the same way that they can move through the spatial dimensions.

 

[fluidistic]

According to wikipedia

Speed is the rate of motion, or equivalently the rate of change of distance.

. I think we all agree on any similar definitions.
Hence the question

what is the speed of time?

has no sense.

 

[HallsofIvy]

what is the speed of time?

One second per second!

 

[Naty1]

Another related interpretation has been discussed in physics forums: our speed through spacetime...in that analogy we pass thru time at "c" when stationary and our passage slows as our speed through space increases...at speed "c" thru space, our passage thru time would slow to zero...

Here is one such excerpt: (Brian Greene, THE ELEGANT UNIVERSE) :

"...Einstein found that precisely this idea - the sharing of motion between different dimensions - underlies all of the remarkable physics of special relativity...
...Einstein proclaimed that all objects in the universe are always traveling through space-time at one fixed speed - that of light...
...If an object dose not move through space all of the objects motion is used to travel through time...
...Something traveling at light speed through space will have no speed left for motion through time. Thus light does not get old; a photon that emerged from the big bang is the same age today as it was then. There is no passage of time at the speed of light."

(quoted from another thread which I just lost...)
Some pooh pooh this concept; I find it at least a very useful analogy; others are unable to conceptualize speed through time.

 

[MeJennifer]

Another related interpretation has been discussed in physics forums: our speed through spacetime...

Point objects are lines in spacetime and spatially extended objects are like tubes. Nothing passes through spacetime with any speed as spacetime is frozen.

 

[Dale]

True, but you can still talk of speed in a geometric sense. Geometrically coordinate speed is the slope of the worldline, and geometrically Naty1's speed (the four-velocity) is a tangent to the worldline.

 

[Max™]

More accurately reflecting the OP: what is the speed of height? If you consider time as a dimension, it doesn't move at all; instead, objects move through the time dimension in the same way that they can move through the spatial dimensions.

Left is not a direction/dimension?

It is not part of Width?

 

[matheinste]

Hello all.

Speed in the directions or dimensions x,y and z is distance paramaterized by time and so we can, if we wish have speed measured in meters per second, one meter being the unit basis vector in each of the spatial directions. I suppose that in spacetime, taking time as a dimension on an equal footing with the other three dimensions, and taking one second as the unit basis vector in the time direction, we should, for consistency, also paramatrerize it by time and so this would give the speed of time, as much as it can "mean" anything, in units of seconds per second. Thus we could give, for a clock at rest in an inertial frame a rate of 1 second per second as measured by itself, or by an observer at rest in the same reference frame.

So as has been said many times before that as much as any meaning can be attached to the question "what is the speed of time?", one second per second seems, to me, to be the most appropriate.

My apologies to any mathematicians for lack of rigor.

Matheinste

 

[DaveC426913]

Left is not a direction/dimension?
It is not part of Width?

Left is a direction in a dimension. If negatron were going to be perfectly literal in correcting you, he would have said "More accurately, what is the speed of width?"

 

[Naty1]

"Point objects are lines in spacetime and spatially extended objects are like tubes."

Isn't this like plotting the course progress of a plane on a map and proclaiming "A plane is line on a map?"

Any attempts to visualize physical phenomena, interpret and record our visualizations and represent them as mathematical formulations are designed more to represent the physical world in ways our limited senses can comprehend than they are objective descriptions. It's only we humans that seem to have trouble understanding natures rules; an atom,for example, always seems to know how its supposed to respond to forces of all types.

Nothing passes through spacetime with any speed as spacetime is frozen.

What does "spacetime is frozen" mean? Is this akin to "all history is fixed"?

And while some on this forum object to this concept of speed thru spacetime, it seems good enough for Brian Greene to utilize. Of course, he might be entirely wrong!

 

[Fredrik]

Another related interpretation has been discussed in physics forums: our speed through spacetime...in that analogy we pass thru time at "c" when stationary and our passage slows as our speed through space increases...at speed "c" thru space, our passage thru time would slow to zero...

Here is one such excerpt: (Brian Greene, THE ELEGANT UNIVERSE) :



(quoted from another thread which I just lost...)
Some pooh pooh this concept; I find it at least a very useful analogy; others are unable to conceptualize speed through time.

I think https://www.physicsforums.com/showthread.php?p=2238569 is the other thread. Greene's explanation is pretty misleading in my opinion, for the reasons I stated there.

 

[The riddler]

its one second per second

 

[A.T.]

"Point objects are lines in spacetime and spatially extended objects are like tubes."

Isn't this like plotting the course progress of a plane on a map and proclaiming "A plane is line on a map?"

I second that. No one objects if a plane icon is shown advancing along a path on a map. Visualizing objects as advancing in space time is no different.

Sure, you can see space time as frozen. That's the point of diagrams with time as dimensions: they describe movement with a static graph. But nothing stops you from imaging the time flow as an animated graph.

And while some on this forum object to this concept of speed thru spacetime, it seems good enough for Brian Greene to utilize. Of course, he might be entirely wrong!

It's not question of right or wrong, but if you like this dynamic visualzation or not.

 

[negitron]

One second per second is not a satisfactory answer because it's not a rate, it's a scale. It's no more a speed than one meter per meter is.

 

[A.T.]

One second per second is not a satisfactory answer because it's not a rate, it's a scale. It's no more a speed than one meter per meter is.

In the http://en.wikipedia.org/wiki/Geometrized_unit_system" time has the dimensin of length, so meter per meter can be a speed. It basically means that a clock at rest advances trough time with 1 lightsecond per second.

 

[matheinste]

One second per second is not a satisfactory answer because it's not a rate, it's a scale. It's no more a speed than one meter per meter is.

I agree. It is not a satisfactory answer because it is a pretty much meaningless or at least ill defined question.

Matheinste

 

[Phrak]

In the http://en.wikipedia.org/wiki/Geometrized_unit_system" time has the dimensin of length, so meter per meter can be a speed. It basically means that a clock at rest advances trough time with 1 lightsecond per second.

Using this logic we can ask what is the speed of distance, and the answer will be one meter per meter.

But why stop here. Can we cast frogs in generalized units too?

 

[The riddler]

O.K Listen, the speed of time cannot be compared to anything. Basic Speed is different because speeds vary, for example you can have a car moving at 6m/s and another car moving at 9m/s. Imagine a universe where everything must move at 1m/s constantly all the time so nothing is going at a speed different to 1m/s, now let's say someone in this universe asks "What is our speed?", but because this universe has nothing to compare its speed to (as everything is going at 1m/s) then their speed is a universal constant and the speed is always 1m/s per 1m/s.

This is the same with time there are no other forms of time you can compare with time, meaning the speed of time can only be compared to itself.

Thus the speed of time is one second per second, please amuse me with more insufficent reasons why you may think this is not so.

P.S: Good anwser Phrak.

 

[negitron]

In the http://en.wikipedia.org/wiki/Geometrized_unit_system" time has the dimensin of length, so meter per meter can be a speed. It basically means that a clock at rest advances trough time with 1 lightsecond per second.

According to that page, velocity has the dimension of 1, so time is expressed in units of 1/L.

 

[A.T.]

Using this logic we can ask what is the speed of distance, and the answer will be one meter per meter.

I agree that "speed of time" doesn't really make sense. But I have no problem talking about "speed in time" of an object, when referring to the ratio: objects_proper_time / coordinte_time

There is no deeper meaning in this. It is rather trivial.

 

[Sumo]

I think Lewis Epstein puts it best in his book "Relativity Visualized".

Inquiring minds will insist in wondering: Why, why, why?...There is no way to explain [it], all that are known is empirical facts. But the inquiring mind is yet unsatisfied...What the inquiring mind yearns for is a little story or myth that will give the feeling of being back home on logical ground... The turtle myth is not good ("turtles all the way down") because it predicts that turtles are at the South Pole. On the other hand the Quantum Field Theory myth is bad because virtually all physicists spend their energy advancing the subject rather than making it easy to understand, so psychic mediums fill the void.

He then goes on to describe the myth that is the one being discussed: That time runs slower in objects moving faster because objects are always moving through time at the speed of light, and must devert that speed to move through space.
As we can see, many people have been deluded by this myth, so that they say things like the wikipedia quote, Green's quote, or the idea that objects "move through time".

I think this question points out the error of the myth. But I also think the myths (or analogies) are important, because that's largely how people think, conceptualize, and thus form new ideas. What we need to do is investigate what time is, and come up with a better myth.

 

[Phrak]

I agree that "speed of time" doesn't really make sense. But I have no problem talking about "speed in time" of an object, when referring to the ratio: objects_proper_time / coordinte_time

There is no deeper meaning in this. It is rather trivial.

I can't see this an being any more than content-free physics. You make the fraction dt/dT, where T is proper time and give it the name 'speed of time'. I take the fraction dx/dX, where X is proper length and call it the 'speed of distance'. The naming is equally content-free.

 

[A.T.]

I agree that "speed of time" doesn't really make sense. But I have no problem talking about "speed in time" of an object, when referring to the ratio: objects_proper_time / coordinte_time

You make the fraction dt/dT, where T is proper time and give it the name 'speed of time'.

No, I don't.
1) I call it "speed in time" not "speed of time"
2) It is dT/dt not dt/dT, (if T is proper time and t is coordinate time).
This is equivalent to calling dx/dt the "speed in space".

I take the fraction dx/dX, where X is proper length and call it the 'speed of distance'. The naming is equally content-free.

Usually a "speed" or "rate" is defined as change_of_something / coordinate_time. This fits my definition above, but not quite yours.

 

[jefswat]

I don't like the label seconds per second as it is misleading and very confusing. If one is inquireing how fast time passes in a different frame relative to another frame I think it linguistically makes more sense to make a distinction between the two seconds(for each different reference frame). Perhaps give it the label "prime seconds per second or something". I would think there is a convention for the label. I don't think that's where the original question was directed but it seems that's where conversation is headed

 

[diazona]

I don't like the label seconds per second as it is misleading and very confusing. If one is inquireing how fast time passes in a different frame relative to another frame I think it linguistically makes more sense to make a distinction between the two seconds(for each different reference frame). Perhaps give it the label "prime seconds per second or something". I would think there is a convention for the label. I don't think that's where the original question was directed but it seems that's where conversation is headed

Confusing to you, but clear to me - on the other hand, I would find "prime seconds per second" quite bewildering. It's a matter of opinion which you prefer, of course, but I think most people would get the point if you say "seconds per second." (In fact, now that I think about it, isn't this "speed in time" related to the rapidity? That's a dimensionless angle, so "seconds per second" makes sense in the sense that the units cancel out...)

 

[monty37]

now,time is a dimension,to us on Earth we say its speed is "1 sec per sec"??
may i know the speed in m/sec. its us passing through time,this what differentiates past
from present.so,how to express speed of time in m/sec??

 

[monty37]

i think the speed of time is the distance ticked every instant by the needle
of the atomic clock per every second. what say?atomic clock is supposed to
be the most accurate timepiece.

 

[A.T.]

now,time is a dimension,to us on Earth we say its speed is "1 sec per sec"??
may i know the speed in m/sec.

It depends on which conversion factor between meters and seconds you choose.Usually the speed of light is used, so the speed trough time of an object at rest would be the speed of light (299 792 458 m / s). But this is just a convenient convention.

 

[Max™]

Left is a direction in a dimension. If negatron were going to be perfectly literal in correcting you, he would have said "More accurately, what is the speed of width?"

I said it is a part of width, which of course implies that you can change it such that height or depth are labeled as such depending on your chosen set of coordinates, x/y/z, etc.

There's no need to "correct" my smart-aleck response, replace "what is the speed of time" with "what is the speed of future" and the quip "what is the speed of left" with "what is the speed of width" would fit just as well.

:P

 

[DaveC426913]

There's no need to "correct" my smart-aleck response, replace "what is the speed of time" with "what is the speed of future" and the quip "what is the speed of left" with "what is the speed of width" would fit just as well.
:P

You're suggesting the original question should be changed to better suit your answer?