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The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

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Re: The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

#11

Post by gus_massa »

InclinedPlane wrote: post #8
deletes wrote: post #5

Earlier quoted context omitted.

There is not much difference. The relativistic factor is 1.030107, that is a ~3% change. EDIT: My amateur physics say that the gravitational well adds 9.7% to that. I tried the same calculation for earth and it gave a sensible result: a change of 6.95 * 10^-10. Here is an answer from physics exchange which gets the same result: http://physics.stackexchange.com/questions/10089/gravitation...

Keep in mind that differences in gravity will also affect time dilation.

And this correction goes in the other way.

Re: The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

#13

Post by deletes »

gus_massa wrote: post #11
InclinedPlane wrote: post #8

Earlier quoted context omitted.

Keep in mind that differences in gravity will also affect time dilation.

And this correction goes in the other way.

No, time in a gravitational well runs more slowly relative to someone outside, just as your experience time slower if you are traveling very fast.

Re: The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

#14

Post by darklajid »

lifeisstillgood wrote: post #12
joezydeco wrote: post #2

Lemme guess, you caught this from http://xkcd.com/1331/ too?

I could not take my eyes off "One Birth" / "One Death" Fascinating - and I think humanity is "winning"

Second kid since yesterday. Fighting for humanity here.. ;-)

Re: The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

#15

Post by gus_massa »

deletes wrote: post #13
gus_massa wrote: post #11

Earlier quoted context omitted.

And this correction goes in the other way.

No, time in a gravitational well runs more slowly relative to someone outside, just as your experience time slower if you are traveling very fast.

You are right. I was confused because the satellites in orbit need a different speed at different height, and in that case the when the special relativity effect increase the general relativity effect decrees. http://en.wikipedia.org/wiki/Error_analysis_for_the_Global_P...

Re: The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

#16

Post by machrider »

deletes wrote: post #13
gus_massa wrote: post #11

Earlier quoted context omitted.

And this correction goes in the other way.

No, time in a gravitational well runs more slowly relative to someone outside, just as your experience time slower if you are traveling very fast.

I think the point was that time in the center of the star is more affected by gravity than at the surface. Whereas someone on the surface (if that were possible) would experience greater time dilation relative to the center due to his high relative velocity. So for those two points (surface vs center), the two time dilation effects are working opposite each other.

Edit: I may have been reading too much into it. The effects you see will depend on which positions you're comparing, and people in this thread haven't really specified.

Re: The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

#18

Post by Crito »

throwaway_yy2Di wrote: post #10
ars wrote: post #7

Anyone feel like calculating the energy embodied in just the rotation of this star?

About 10^46 J? In the classical approximation (1/2 Iω^2), assuming a uniform sphere of 2.0 solar masses and r=16 km. That's about 3% of the mass-energy (mc^2 = 3e47 J). This could be way off.

Wolfram Alpha has 10^46 J as 100x the energy given off by a supernova. I don't know if that means your numbers are off, or if this star is just mind-bendingly insane.

Re: The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

#19

Post by deletes »

machrider wrote: post #16
deletes wrote: post #13

Earlier quoted context omitted.

No, time in a gravitational well runs more slowly relative to someone outside, just as your experience time slower if you are traveling very fast.

I think the point was that time in the center of the star is more affected by gravity than at the surface. Whereas someone on the surface (if that were possible) would experience greater time dilation relative to the center due to his high relative velocity. So for those two points (surface vs center), the two time dilation effects are working opposite each other. Edit: I may have been reading too much into it. The e…

I think you mixed up some things. There is no gravity or time dilation in the center of a massive spherical object.

Re: The fastest pulsar spins at 716Hz; its equator spins at 24% the speed of light

#20

Post by einrealist »

lifeisstillgood wrote: post #12
joezydeco wrote: post #2

Lemme guess, you caught this from http://xkcd.com/1331/ too?

I could not take my eyes off "One Birth" / "One Death" Fascinating - and I think humanity is "winning"

It makes me sad because most of the births are in underdeveloped countries, where people have no access to clean water and healthy food. And as more people of countries like China enter middle class, the resources we depend on, will diminish faster and faster.
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