if we have a laser beam perpendicular to an approachin bullet, would we observe doppler effect for the instant when the laser strikes the bullet???
if we have a laser beam perpendicular to an approachin bullet, would we observe doppler effect for the instant when the laser strikes the bullet???
please i really need to know
QUOTE (doppler+Jul 26 2009, 06:08 AM)
if we have a laser beam perpendicular to an approachin bullet, would we observe doppler effect for the instant when the laser strikes the bullet???
Why would we see a Doppler Effect? The laser light won't change frequencies after it hits the bullet, if that's what you mean.
Why would we see a Doppler Effect? The laser light won't change frequencies after it hits the bullet, if that's what you mean.
No. The relativistic transverse Doppler effect applies to sources, not to reflected light. It is a statement about clocks. And a laser (being monochromatic light) is a type of clock, with regular intervals of time separating the peaks of the wave.
Since the laser bounces off the bullet, we only measure our own clock, and we are never Doppler shifted to ourselves.
http://www.iop.org/EJ/abstract/0022-3735/10/3/017
Since the laser bounces off the bullet, we only measure our own clock, and we are never Doppler shifted to ourselves.
http://www.iop.org/EJ/abstract/0022-3735/10/3/017
QUOTE (rpenner+Jul 26 2009, 04:07 PM)
No. The relativistic transverse Doppler effect applies to sources, not to reflected light. It is a statement about clocks. And a laser (being monochromatic light) is a type of clock, with regular intervals of time separating the peaks of the wave.
Since the laser bounces off the bullet, we only measure our own clock, and we are never Doppler shifted to ourselves.
http://www.iop.org/EJ/abstract/0022-3735/10/3/017
great reference; but I don't see why its a clock effect ;a laser 'clock' bouncing off an object with radial motion is doppler shifted....so what makes transverse doppler differnent?
BTW, where can I get a copy on-line, not being an IOP subsciber?
...
Since the laser bounces off the bullet, we only measure our own clock, and we are never Doppler shifted to ourselves.
http://www.iop.org/EJ/abstract/0022-3735/10/3/017
great reference; but I don't see why its a clock effect ;a laser 'clock' bouncing off an object with radial motion is doppler shifted....so what makes transverse doppler differnent?
BTW, where can I get a copy on-line, not being an IOP subsciber?
...
Because for radial motion, the description of the operation of reflection is simplest in the frame of the mirror. And in that frame, the light is blue- or red- shifted.
For transverse motion, in the frame of the mirror, not only is the light time-dilated, but the path is diagonal. A full treatment should reveal that the diagonal is just the right angle to cancel out any transverse effect. And so it should be consistent in both frames that no Doppler shift is observed. (Anyone have a good site or textbook reference for this?)
For transverse motion, in the frame of the mirror, not only is the light time-dilated, but the path is diagonal. A full treatment should reveal that the diagonal is just the right angle to cancel out any transverse effect. And so it should be consistent in both frames that no Doppler shift is observed. (Anyone have a good site or textbook reference for this?)
QUOTE
Because for radial motion, the description of the operation of reflection is simplest in the frame of the mirror. And in that frame, the light is blue- or red- shifted.
well; doesn't 'doppler radar' imply a shift in the receiver frame, aka, in the cop car.?
QUOTE (->
| QUOTE |
| Because for radial motion, the description of the operation of reflection is simplest in the frame of the mirror. And in that frame, the light is blue- or red- shifted. |
well; doesn't 'doppler radar' imply a shift in the receiver frame, aka, in the cop car.?
For transverse motion, in the frame of the mirror, not only is the light time-dilated, but the path is diagonal. A full treatment should reveal that the diagonal is just the right angle to cancel out any transverse effect. And so it should be consistent in both frames that no Doppler shift is observed. (Anyone have a good site or textbook reference for this?)
thanks for the post ...I can see I really have to read up on the basics of transverse doppler effect.
So apparently, the relativisitic (transverse) is only applicable for source, not reflection? apparently due to the symmetry. There was some confusion as to that until recently... I trust Paul Davies though.
That's why I want ot get the referenced report you cited.
Lunar
....
hey...thanks everyone 
umm...so wat exactly would happen to the laser beam after hitting the bullet???
would there be backsctatter or simple reflection???
umm...so wat exactly would happen to the laser beam after hitting the bullet???
would there be backsctatter or simple reflection???
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