Question about pulsars


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Profile Bob DeWoody
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Message 1293689 - Posted: 11 Oct 2012, 3:17:49 UTC

OK, as I understand it pulsars spin at various high rates and when they are aligned just right the pulses can be detected by radio telescopes. The first one detected was believed at first to be the source of an ET signal. They are compared to the light generated in a lighthouse spinning at a regular interval. For comparison on a large spinning propeller attached to an aircraft motor it is possible for the tip to actually spin at a speed exceeding the speed of sound. So at a sufficient distance from a spinning pulsar is the beam of energy moving faster than the speed of light as it sweeps through 360 degrees of arc?
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Message 1293695 - Posted: 11 Oct 2012, 4:02:45 UTC
Last modified: 11 Oct 2012, 4:04:26 UTC

I think that you are imagining the light beam as a solid thing. It isn't. It is composed of individual photons moving out from the source at the speed of light. The instant that it leaves the pulser each individual photon travels out straight, it doesn't swing through space like a prop spins on a hub.

Part of the problem with using metaphor to explain scientific ideas is that folks can take it too literal.
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Message 1293734 - Posted: 11 Oct 2012, 7:07:58 UTC

Einstein@home, while the laser interferometers used to search for gravitational waves are being upgraded, is searching for pulsars in the data from Arecibo, Parkes (Australia) and Fermi gamma-ray satellite. It found about 50 new pulsars from the first 2 sources, while data from Fermi are not yet available. Each volunteer who happens to discover a pulsar with another volunteer is given a certificate. So far I got none.
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Message 1293742 - Posted: 11 Oct 2012, 8:10:10 UTC - in response to Message 1293689.
Last modified: 11 Oct 2012, 8:13:57 UTC

... So at a sufficient distance from a spinning pulsar is the beam of energy moving faster than the speed of light as it sweeps through 360 degrees of arc?

Bob,
According to Einstein, the answer to your question is No! According to Einstein, the beam of Energy is not travelling faster than the speed of light! According to Einstein's rules, if you think a beam of light appears to move faster than light, its an optical illusion. According to Einstein, nothing moves faster than light, full stop!

Of coarse, personally myself, i disagree with almost everything Albert Einstein wrote. And there are many other people just like me that see flaws in Einsteins work.

John.
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Message 1293750 - Posted: 11 Oct 2012, 9:13:43 UTC

Of coarse, personally myself, i disagree with almost everything Albert Einstein wrote. And there are many other people just like me that see flaws in Einsteins work.

You are in the minority then.

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Message 1293775 - Posted: 11 Oct 2012, 12:16:33 UTC - in response to Message 1293742.
Last modified: 11 Oct 2012, 12:17:46 UTC

According to Einstein, nothing moves faster than light, full stop!


Not quite, nothing with mass moving through spacetime can be accelerated to 'c', and the speed of massless particles through a vaccum in spacetime is 'c'. 'c' is often termed the "speed of light" though the constant need not be the speed of light in a vacuum, if photons were discovered to have mass, it would not be possible for them to travel at the speed 'c'.

'c' was derived by Maxwell as a result of unifying electrical and magnetic phenomena.

Einstein did not state whether spacetime itself could grow at speeds in excess of 'c'.
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I think you'll find it's a bit more complicated than that ...

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Message 1293810 - Posted: 11 Oct 2012, 15:10:35 UTC
Last modified: 11 Oct 2012, 15:21:44 UTC

Not directly related to pulsars, but perhaps a similar example which came up in my mind.

Suppose you are standing besides a road carrying a flashlight in your hand.

At the same time someone else driving in a car at 50 mph passes you traveling in one direction. In the exact same moment the car passes you, you turn on the flashlight in the same direction as the car is heading. Similarly, when the car passes you, it turns on its headlights as well.

Both the light from the flashlight as well as the car headlights are supposed to be illuminating the area in front of their position. Suppose there is something in front there (like a reflecting sign besides the road) which is able to return the lights.

The question then becomes: From which object (the handheld flashlight or the car headlights) is light supposed to be received by the reflecting sign first and who is then supposed to see the reflection of the light as it is being returned to both you standing there as well as the car which in the meantime has traveled a very insignificant distance? What if the reflecting sign is a moving object on its own?

We are back to the question of motion of objects through space vs. time. Objects relate towards each other in a specific manner because of such motions through space. It is assumed to be taking a specific amount of time as well.

In the same way, matter which are thrown out of pulsars (photons or something else) is supposed to be particles which are having mass. Such matter is not supposed to be traveling at the speed of light at all. But assumedly photons are able to attain the speed of light.

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Message 1293819 - Posted: 11 Oct 2012, 15:32:38 UTC - in response to Message 1293775.

... 'c' was derived by Maxwell as a result of unifying electrical and magnetic phenomena.

Einstein did not state whether spacetime itself could grow at speeds in excess of 'c'.

According to our theory of a period of Hyperinflation during an early part of the Big Bang, possibly so.

And still we expand... The equation there is brilliantly mind bending in implication and portent... ;-)


Keep searchin',
Martin

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Message 1293821 - Posted: 11 Oct 2012, 15:38:12 UTC - in response to Message 1293810.

Not directly related to pulsars, but perhaps a similar example which came up in my mind.

Suppose you are standing besides a road carrying a flashlight in your hand. ...

It's all relative to the particular source/observer. Time/frequency shifts to keep the apparent speed of light constant relative to their frame of reference.

Hence you see a Doppler shift.


Keep searchin',
Martin

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Message boards : Science (non-SETI) : Question about pulsars

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