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### Re: Speed of time ?

Posted: Sun Apr 26, 2015 10:39 pm
Ginkgo wrote: No, it is actually relevant. I found this very good explanation:

Einsteins Special and General Relativity in Everyday Life.

But in a relativistic world, things are not simple. The satellite clocks are moving at 14,000 km/hr in orbits that circle the Earth twice per day, much faster than clocks on the surface of the Earth, and Einstein's theory of special relativity says that rapidly moving clocks tick more slowly, by about seven microseconds (millionths of a second) per day.

Also, the orbiting clocks are 20,000 km above the Earth, and experience gravity that is four times weaker than that on the ground. Einstein's general relativity theory says that gravity curves space and time, resulting in a tendency for the orbiting clocks to tick slightly faster, by about 45 microseconds per day. The net result is that time on a GPS satellite clock advances faster than a clock on the ground by about 38 microseconds per day.

This is the relevant bit from the physics website. In fact you can find this information on any physics website.
In other words what I said was correct. Altitude means that clocks will travel at different velocity and this affects the time.
What was irrelevant is you pointing out the "difference" between general and special.

### Re: Speed of time ?

Posted: Sun Apr 26, 2015 10:51 pm
Hobbes' Choice wrote:
Ginkgo wrote: No, it is actually relevant. I found this very good explanation:

Einsteins Special and General Relativity in Everyday Life.

But in a relativistic world, things are not simple. The satellite clocks are moving at 14,000 km/hr in orbits that circle the Earth twice per day, much faster than clocks on the surface of the Earth, and Einstein's theory of special relativity says that rapidly moving clocks tick more slowly, by about seven microseconds (millionths of a second) per day.

Also, the orbiting clocks are 20,000 km above the Earth, and experience gravity that is four times weaker than that on the ground. Einstein's general relativity theory says that gravity curves space and time, resulting in a tendency for the orbiting clocks to tick slightly faster, by about 45 microseconds per day. The net result is that time on a GPS satellite clock advances faster than a clock on the ground by about 38 microseconds per day.

This is the relevant bit from the physics website. In fact you can find this information on any physics website.
In other words what I said was correct. Altitude means that clocks will travel at different velocity and this affects the time.
What was irrelevant is you pointing out the "difference" between general and special.

Moving clocks tick slower. Special relativity.

Clocks above the earth experience weaker gravity-they tick faster. General relativity.

GPS satellites are both moving and above the earth so special and general relativity have to be taken into account.

### Re: Speed of time ?

Posted: Sun Apr 26, 2015 10:54 pm
Ginkgo wrote:
Hobbes' Choice wrote:
Ginkgo wrote: No, it is actually relevant. I found this very good explanation:

Einsteins Special and General Relativity in Everyday Life.

But in a relativistic world, things are not simple. The satellite clocks are moving at 14,000 km/hr in orbits that circle the Earth twice per day, much faster than clocks on the surface of the Earth, and Einstein's theory of special relativity says that rapidly moving clocks tick more slowly, by about seven microseconds (millionths of a second) per day.

Also, the orbiting clocks are 20,000 km above the Earth, and experience gravity that is four times weaker than that on the ground. Einstein's general relativity theory says that gravity curves space and time, resulting in a tendency for the orbiting clocks to tick slightly faster, by about 45 microseconds per day. The net result is that time on a GPS satellite clock advances faster than a clock on the ground by about 38 microseconds per day.

This is the relevant bit from the physics website. In fact you can find this information on any physics website.
In other words what I said was correct. Altitude means that clocks will travel at different velocity and this affects the time.
What was irrelevant is you pointing out the "difference" between general and special.

Moving clocks tick slower. Special relativity.

Clocks above the earth experience weaker gravity-they tick faster. General relativity.

GPS satellites are both moving and above the earth so special and general relativity have to be taken into account.
Clocks that the top of a mountain: 1) travel faster, 2) experience less gravity, but negligably.
or is this self compensating?

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 11:35 am
They don't cancel each other out if this is what you mean.

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 2:14 pm
Ginkgo wrote:They don't cancel each other out if this is what you mean.
If proximity to gravity has one effect on time, and velocity has the opposite effect on time, then there must be a slope of velocity against gravity field intensity, where one effect cancelled out the other.

Unless you have mischaracterised the effects?

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 3:19 pm
Ginkgo wrote:
duszek wrote:Velocity (or speed) is defined by time.
Time is one of the defining elements.

It is for example 100 miles per hour.

Instead of time we could take sunsets and also express velocity:

I move 10 miles per 3 sunsets.

In relation to your original question. Yes, people on mountains live and more more quickly than people living at sea level.It all depend on the reference frame. People on mountains who live and more more quickly don't notice the difference because their metabolism also keeps pace with faster time.

The important point is there is not absolute time, regardless how we choose to measure it.
But if the reference frame is the rising and the setting of the sun (or the chanting of a rooster) then time does not move faster in the mountains.

And their metabolism does not move faster either.

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 3:24 pm
Ginkgo wrote:

Moving clocks tick slower. Special relativity.

Clocks above the earth experience weaker gravity-they tick faster. General relativity.

GPS satellites are both moving and above the earth so special and general relativity have to be taken into account.
All kind of clocks tick faster in the mountains ?

How about sand clocks ? Does sand move faster through the hole if the gravitation is weaker ? It should rather be the other way round.

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 3:48 pm
duszek wrote:
Ginkgo wrote:
duszek wrote:Velocity (or speed) is defined by time.
Time is one of the defining elements.

It is for example 100 miles per hour.

Instead of time we could take sunsets and also express velocity:

I move 10 miles per 3 sunsets.

In relation to your original question. Yes, people on mountains live and more more quickly than people living at sea level.It all depend on the reference frame. People on mountains who live and more more quickly don't notice the difference because their metabolism also keeps pace with faster time.

The important point is there is not absolute time, regardless how we choose to measure it.
But if the reference frame is the rising and the setting of the sun (or the chanting of a rooster) then time does not move faster in the mountains.

And their metabolism does not move faster either.
You are missing the point of relativity.
If you live in a mountain, you travel faster than at the bottom of the ocean (on the same longitude). This is because you describe a larger circumference on a virtual circle with it's centre at the earth's core.
In the same way you would be traveling much more slowly at the poles, as you would only be going round in small circles.
Time elsewhere goes more quickly when you are going fast.
Thus at the poles you get older more quickly than a person on a mountain at the equator.

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 3:51 pm
duszek wrote:
Ginkgo wrote:

Moving clocks tick slower. Special relativity.

Clocks above the earth experience weaker gravity-they tick faster. General relativity.

GPS satellites are both moving and above the earth so special and general relativity have to be taken into account.
All kind of clocks tick faster in the mountains ?

No, all clocks tick at the same rate where ever they are. But from an observer in space people at the poles pass the time more quickly; people on a mountain or at the equator more slowly.

Were you to travel at close to the speed of light, everyone on earth would be dead before you got back to earth.

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 4:40 pm
They cannot tick at the same rate.
Those depending on gravitation tick at different rates, depending on how far from the center of the earth they are.

Those not depending on gravitation (or depending on a different centre of gravity) have their own rate.

That´s the whole point.

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 4:57 pm
duszek wrote:They cannot tick at the same rate.
Those depending on gravitation tick at different rates, depending on how far from the center of the earth they are.

Those not depending on gravitation (or depending on a different centre of gravity) have their own rate.

That´s the whole point.
No, all clocks tick at the same rate where ever they are. That's why they call it relativity.

### Re: Speed of time ?

Posted: Mon Apr 27, 2015 5:45 pm
What do you mean by "ticking at the same rate" ?

If one person were watching the clock on the beach and another one were watching the clock on the mount and if after 10 days they compared how much "time" had passed so far the results would be a tiny little bit different. They could communicate by a mobile phone and compare what they see.

### Re: Speed of time ?

Posted: Tue Apr 28, 2015 8:30 am
The speed of light in vacuum is a constant but time and space are not. This is why the fabric of spacetime can be distorted by General
Relativity
with regard to the gravitational force exerted by massive objects such as stars. Far as time is concerned a moving clock uses
up more energy than a static one. For objects approaching light speed time would physically stop. Though this is actually impossible as
infinite mass would occur too. And infinities in physics when applied to reality are meaningless. And this is why the singularity which is
supposed to be at the beginning of the Big Bang is problematic. As it references not one but two of them : the negative infinity of zero
volume and the positive infinity of infinite mass. Infinities are fine in maths but do not translate to reality as that is finite by definition

### Re: Speed of time ?

Posted: Tue Apr 28, 2015 10:51 am
duszek wrote:What do you mean by "ticking at the same rate" ?

If one person were watching the clock on the beach and another one were watching the clock on the mount and if after 10 days they compared how much "time" had passed so far the results would be a tiny little bit different. They could communicate by a mobile phone and compare what they see.
Each clock continues to tick at the rate rate relative to the local time frame. A person on the beach would see the same thing when he looked at the clock as the person on the mountain. What would be different is the time comparison. The mountaineer would be younger as would his clock.

### Re: Speed of time ?

Posted: Tue Apr 28, 2015 10:54 am
surreptitious57 wrote:The speed of light in vacuum is a constant but time and space are not. This is why the fabric of spacetime can be distorted by General
Relativity
with regard to the gravitational force exerted by massive objects such as stars. Far as time is concerned a moving clock uses
up more energy than a static one. For objects approaching light speed time would physically stop. Though this is actually impossible as
infinite mass would occur too. And infinities in physics when applied to reality are meaningless. And this is why the singularity which is
supposed to be at the beginning of the Big Bang is problematic. As it references not one but two of them : the negative infinity of zero
volume and the positive infinity of infinite mass. Infinities are fine in maths but do not translate to reality as that is finite by definition
Yes, I don't really think this is a problem. We have to conclude that either the BB is nothing more than a theoretical construct, and did not occur in the way it is presented, or that the laws of physics emerged in tandem with it, and the explosion is the expression of the birth of the order of physical law.
The fact is we can never, and shall never know. It's all speculation.