Whats wrong with Gravity?

[tytower]

Watched a TV show called this last night.
Fella presenting claimed a Particle Physics Doctorship
Reckoned GPS has to be adjusted periodically because the clocks on board the satellites run faster with the lesser gravity.

He passed over it very quickly claiming it was 10 minutes a day! Now he was at a US Airforce base with no airstrip which specialised in GPS for the military.

I reckon somebody was pulling his leg but you would imagine he would know his stuff.

Anybody know anything about this ? Anybody seen any sites or reports on this?
Thanks IA

 

[Boron]

I don't quite remember where I heard this claim, but the way I believe it works is as follows.

Because the satellites are moving very fast with respect to the earth, they suffer from time dilation, in keeping with special relativity. As such the clocks on board the satellites will run slower than those on earth and a periodic sync or compensation is required.

Makes sense I think.

 

[birdman0_o]

**broken link removed**

1 s / sqrt (1 - (40 000km/s^2)/(300 000km/s^2)

sooo new t = 1.009009191s so yea, I dunno....

so in a day that's : 12.97 minutes !

If you want to live longer, go live in space

 

[tcmtech]

That seems to present a bit of a time travel conundrum. They are moving though time slower than us but we can still interact with them in perceived real time as well.

If they are running 87 seconds per day slower then after being in operation for around ten years they should be about 88.27 hours behind us. So shouldn't the signal we sent them now be picked up 88.27 hours



time slip.

See different time line for continuation of paragraph and explanations of information relating who does what in the next 88.27 hours.

Birdman has since edited his equation to a different time than the 87 second referance I used here.
Time changes things. Go figure.

 

[birdman0_o]

TCM, radio signals are not affected by time dilation

 

[tytower]

Ah OK
Well the proposition was that time in fact is slowed by Gravity not speeded up . So this would suggest that living in space free of gravity time would run faster and you would come back younger than your twin brother left on earth.

This was not based on speed . It was based on Gravity . Einstein's theory of special relativity and a spaceman going into space and coming back younger was based on speed and has been proved wrong.
Now don't come backat me on this go Google it up.

If you still believe Einsteins theories sound then offer a proof . I have asked many experts and the only rational proof that was offered related to muons being split by cosmic rays and their speed of entry into the atmosphere being measured. I could find no physical proof whatever . Students learn this by rote and spout it without any proof.

 

[tytower]

**broken link removed**

1 s / sqrt (1 - (40 000km/s^2)/(300 000km/s^2)

sooo new t = 1.009009191s so yea, I dunno....

so in a day that's : 12.97 minutes !

If you want to live longer, go live in space

Amazing how all these formulas quote the speed of light . A really big number in other words . A convenient way of saying "ha ha nobodys ever going to question this "

If time is not an absolute then is the speed of light . If time is faster in space then our calculations of the length of time light has taken to reach us could be massively out.

Pictures claiming to be of galaxies 10 billion light years away may only be 1 if the light has not been anywhere near a black hole on its course?

 

[Boron]

I did google it:

In October 1971, Hafele and Keating flew cesium-beam atomic clocks, initially synchronized with the atomic clock at the US Naval Observatory in Washington, D.C., around the world both eastward and westward. After each flight, they compared the time on the clocks in the aircraft to the time on the clock at the Observatory. Their experimental data agreed within error to the predicted effects of time dilation. Of course, the effects were quite small since the planes were flying nowhere near the speed of light.

Reference:

Hafele and Keating Experiment
or J.C. Hafele and R. E. Keating, Science 177, 166 (1972)

And before you tell me they lied or that the "acceptable error" was way too big or whatever other excuse, the experiment was reproduced in subsequent years with ever increasing accuracy, always indicating special relativity was and is correct.

Yes time would speed up a little because of the decreased gravity. How big an effect that would have compared to the velocity issue I personally do not know. My intuition would be that its very small.

 

[tcmtech]

1 s / sqrt (1 - (40 000km/s^2)/(300 000km/s^2)
sooo new t = 1.009009191s so yea, I dunno....
so in a day that's : 12.97 minutes !

Are you sure your equation is right this time?

 

[DirtyLude]

This was not based on speed . It was based on Gravity . Einstein's theory of special relativity and a spaceman going into space and coming back younger was based on speed and has been proved wrong.
Now don't come backat me on this go Google it up.

If you still believe Einsteins theories sound then offer a proof . I have asked many experts and the only rational proof that was offered related to muons being split by cosmic rays and their speed of entry into the atmosphere being measured. I could find no physical proof whatever . Students learn this by rote and spout it without any proof.

Seriously, WTF? What back alley experts have you asked? Maybe you should have googled this before telling other people too. Time dilation due to velocity differences has been proved many times in many ways. It's one of the basics of relativity theory.

Geez, Wikipedia of all things. Talks about velocity and gravitational time dilation and gives experimental references for both.

Time dilation - Wikipedia, the free encyclopedia

...and Borons reference.

 

[birdman0_o]

TCM, my calculation is correct.

 

[tcmtech]

Seriously, WTF? What back alley experts have you asked? Maybe you should have googled this before telling other people too. Time dilation due to velocity differences has been proved many times in many ways. It's one of the basics of relativity theory.
Geez, Wikipedia of all things. Talks about velocity and gravitational time dilation and gives experimental references for both.

LOL and ROFL!

fair chance you get negative rep points for it.

I dont follow the time/speed relativity principals all that well (just not my area) but for the most part I do think that when the big name scientists and countless others have tested and retested something I can be fairly safe in assuming that they are probably more right than wrong.

TCM, my calculation is correct.

Just checking. being you went from 87 seconds to 12.97 minutes.
If you say so I will believe you being I never was any good at using foreign language alphabets for math.

 

[birdman0_o]

Well, firstly. I used 40km/h instead of seconds. I then fixed that mistake.
Secondly, i calculated total time in a by doing * 1.009 but i should have just done .009.

Sorry to sound less convincing

If you don't believe me pull out your calculator!

 

[tcmtech]

I went to public school. We didn't get into speed/time relativity theory.
My school couldn't even keep the clocks from one classroom to the next on the right time. This was way over our heads.

I would check your math but I cant find the T, V, triangle, or the check mark on my Casio. All I got is numbers and when I press the C key everything just gets erased.

 

[Pommie]

LOL and ROFL!

fair chance you get negative rep points for it.

Fair chance he'll get positive rep as well.

Mike.

 

[kchriste]

I'm surprised that the obvious question hasn't been asked, "Does a satellite rust faster on the ground with the battery (+) connected to the hull vs one in space with the battery (-) connected to the hull?"

 

[Roff]

**broken link removed**

1 s / sqrt (1 - (40 000km/s^2)/(300 000km/s^2)

sooo new t = 1.009009191s so yea, I dunno....

so in a day that's : 12.97 minutes !

If you want to live longer, go live in space

What travels at ≈1/8 the speed of light (40,000 km/s)?

 

[birdman0_o]

A GPS satellite

**broken link removed**

 

[birdman0_o]

Wow im blind! yet another mistake....4km/s!!!! eeeeks.

Time to fix my calculation again

 

[birdman0_o]

1 s / sqrt (1 - (4 000km/s^2)/(300 000km/s^2)

sooo new t = 1.00000889s

so in a day that's : 7.68s

The OP is wrong...as one would expect.