[Dudley]

Dudley asked the Naked Scientists:
   
As time slows down relative to speed, would the world go at a faster rate if it were to stop? It orbits the sun at about 82000 miles per day. Would time pass slower or faster on another planet, or in another galaxy. Or is time something that man has invented ?


Or is it part of the space-time continuum which I find difficult to understand.

What do you think?

[Soul Surfer]

Time dilation only happens if you are watching someone else moving very fast i.e. close to the velocity of light that is 186,000 miles per SECOND.  Time always passes normally for the observer

[MikeS]

Time dilation only happens if you are watching someone else moving very fast i.e. close to the velocity of light that is 186,000 miles per SECOND.  Time always passes normally for the observer

Time is dilated relative to somewhere else and is reciprocal.
Time obviously has not dilated for the rest of the universe as it appears from the reference frame of the fast moving individual, it just appears that it has. 
Time actually has dilated for the fast moving individual but they are unaware of it as they are within that time frame. 
They could be aware that it is their time frame that is dilated by observing all other clocks outside their time frame as being dilated.

[jartza]

Yes clocks would speed up if world stopped.

The well known Twin Paradox: Twin A makes a space trip, twin B stays still, after the trip twin B is older.

Just replace people with planets in the previous sentence.

[simplified]

Dudley asked the Naked Scientists:
   
As time slows down relative to speed, would the world go at a faster rate if it were to stop? It orbits the sun at about 82000 miles per day. Would time pass slower or faster on another planet, or in another galaxy. Or is time something that man has invented ?


Or is it part of the space-time continuum which I find difficult to understand.

What do you think?

Time is a parameter of movement. Movement at slowed  time is slower than identical movement at fast time.Time can be slower or faster,this means that identical movements can be slower or faster.You should not believe in space-time without full experimental confirmation,because it gives less than steals.

[yor_on]

No, it would not 'speed up'. Time is something pointing one way for you, and it has the same pace wherever you go. But to live is to communicate, and to communicate you need a medium. That medium is radiation and gravity as I see it. Gravity defines SpaceTime, with radiation defining the 'speed' of communication.

The speed of light in a vacuum.

That's how fast you will be able to exchange meaningful information. And that 'speed limit' doesn't change by you going faster or slower. It always have only one value, why? A very good question. Much of modern physics search for a way around that fact, but we still haven't found it, more than a hundred years later.

You see, when people, scientists whatever, try to understand this universe we have to build on what it shows us. Most of those things one can relate to other things and they become a chain of sorts, explaining why they 'work'. But they all seem to end, or start, with 'constants'. SpaceTime borders that just 'exist', and 'c' (and the way it never change 'locally') is one of those. That we even invented the necessity of stating 'locally' should show you the lengths we go to in our effort to find ways around this border. It's a very strange one.

It's 'c' that creates a 'time dilation' and a 'length contraction', the fact that it is invariant.

[MikeS]

It's 'c' that creates a 'time dilation' and a 'length contraction', the fact that it is invariant.

That's arguable.  I would suggest that time dilation is due to acceleration (gravity) and its effect is to keep 'c' constant.  Not the other way around.

[simplified]

It's 'c' that creates a 'time dilation' and a 'length contraction', the fact that it is invariant.

That's arguable.  I would suggest that time dilation is due to acceleration (gravity) and its effect is to keep 'c' constant.  Not the other way around.

It's 'c' that creates a 'time dilation' and a 'length contraction', the fact that it is invariant.

That's arguable.  I would suggest that time dilation is due to acceleration (gravity) and its effect is to keep 'c' constant.  Not the other way around.

It's 'c' that creates a 'time dilation' and a 'length contraction', the fact that it is invariant.

That's arguable.  I would suggest that time dilation is due to acceleration (gravity) and its effect is to keep 'c' constant.  Not the other way around.

A traveling light ,to us, has less speed relatively of us in space of another galaxy.In space of our galaxy it gets 'c'. []

[yor_on]

Depends, I think of the universe as a flickering one
It has one perfect 'clock'. 'c'

You make all measurements under that clock, and we find that there is a scale in which we can't define it any further, the Planck scale. It is the time required for light to travel, in a vacuum, a distance of one Planck length. Going further down stops to make sense physically and mathematically, as main stream science defines it. Planck time.

"Before a time classified as a Planck time, 10-43 seconds, all of the four fundamental forces are presumed to have been unified into one force. All matter, energy, space and time are presumed to have exploded outward from the original singularity. Nothing is known of this period." And "As of May 2010, the smallest time interval that was directly measured was on the order of 12 attoseconds (12 × 10−18 seconds),[4] about 1024 times larger than the Planck time."

All of that makes a perfect sense of you think of radiation as a 'invariant' clock. As I see it we live by the beat of 'c'. And that beat happens at that Planck length described.

Then we come to gravity. There both you and me attach a importance, and a unique quality, to it. To me it is what makes 'SpaceTime' measurable, defining its three(four)dimensionality. And as 'gravity' bends the geometry of SpaceTime we find 'clocks' to tick slower, relative the 'far observer' that is. But not as seen if he would be in that 'frame of reference'. And that one is directly related to 'distance' as being frame dependent, as well as time.
==

There is one more thing to notice. If the universe indeed 'flicker', then all observations we make can only be made while it's 'on'. So even if we wanted to define this as some 'smallest bit' it would still be a 'flow' to us, not 'bits'. We're only 'on' as the universe is 'on', if so. And the 'flickering' is the clocks invariant beat to me. There are other ways to see it too, a 'number space' for example where all motion is described by some 'number/symbol' changing a value. That one would give us a still universe, with only 'times arrow' defining what we see. And both can be put together, and are, in my mind . But then again, it's my view.
=

One thing that is special with gravity as a 'clock' is that all observers will agree to the difference. "An observer at the top of a tower will observe that clocks at ground level tick slower, and observers on the ground will agree about the direction and the ratio of the difference. There is not full agreement, as all the observers make their own local clocks out to be correct, but the direction and ratio of gravitational time dilation is agreed by all observers, independent of their altitude."

But when it comes to relative motion this change. "In special relativity, the time dilation effect is reciprocal: as observed from the point of view of either of two clocks which are in motion with respect to each other, it will be the other clock that is time dilated. (This presumes that the relative motion of both parties is uniform; that is, they do not accelerate with respect to one another during the course of the observations.)" From Time dilation.

That makes relative uniform motion a special case to me, and I'm still struggling with how to see it. An acceleration is 'gravity' locally, and can be defined from that. But, in the end, all motion confuse me. It has to do with the geometry, and gravity, but how? And it must have to do with 'energy, and the way it is distributed, displaced, whatever?

The universe is weird