- #1
vJames
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Hi all,
I've got a high school special relativity physics test coming up in a week and thought I should post here instead of under homework/coursework as I don't really have any set questions that I'm asking.
My problem is that I can explain the visual effects we learned but not with enough depth and understanding that I think I will need for the test.
We looked at 4 visual effects mainly, these being: angular compression with the headlight effect, the Doppler effect and Terrell Rotation.
It's likely we will be required to identify and comment on photos from movies/animations etc. that illustrate different optical effects of special relativity.
Does anyone have any good sites or possibly their own explanation that can assist me with my understanding?
I'll try to give my explanation/interpretation of the visual effects and I would appreciate any feedback on mistakes or gaps in my knowledge.
My explanations-
Terrell Rotation:
At any given moment, all light being received by the observer has reached the observer at the same time. In order for all light from different sources to arrive at the same time and Einstein's second postulate of special relativity to hold true, the light would have left different sources at different times. Therefore, light from a source at a greater distance would have subsequently left the source earlier to arrive at the same time as light leaving a source at a shorter distance.
Objects that are viewed on an angle from an observer traveling at relativistic speeds appear to rotate as a time lag exists between light leaving the further points of the object and when light leaves the closer points of the object. As the object moves or is perceived to move at a relativistic speed, the light sources do not line up with the true shape of the object. This results in a rotated visual distortion of passing objects to the observer.
Doppler Effect:
The Doppler effect explains shifts in the observed wavelengths of light seen by an observer traveling at relativistic speeds. As an observer approaches a light source, the observed wavelength of light will be compressed and they will see the oncoming light with a higher frequency, causing a blue-shift towards the shorter wavelength side of the spectrum. Light from receding sources will undergo rarefaction as the waves are being emitted in the opposite direction of motion. To an observer, a red-shift is seen as the wavelength of light increases and the frequency decreases.
A side note: If the Doppler effect is an optical effect, am I correct in saying that a blue-shift does not mean that you are seeing more energetic light, but just a visual effect of light that appears to be at a higher frequency? In other words, does it mean that blue-shift light has more energy?
Angular Compression (This confuses me.)
I've seen the diagrams of angular compression and a few visual animations but unfortunately our teacher didn't cover the cause of it very clearly. I've heard the aberration of rain comparison but I just can't understand how rain that appears angled to an observer in motion is comparable to an observer at relativistic speeds that can see light from almost 360 degrees around him in his center field of vision.
I'm sorry if I've rambled on, but I've needed a bit of space to try and lay out my thoughts and think about what I know and don't know.
Thanks.
I've got a high school special relativity physics test coming up in a week and thought I should post here instead of under homework/coursework as I don't really have any set questions that I'm asking.
My problem is that I can explain the visual effects we learned but not with enough depth and understanding that I think I will need for the test.
We looked at 4 visual effects mainly, these being: angular compression with the headlight effect, the Doppler effect and Terrell Rotation.
It's likely we will be required to identify and comment on photos from movies/animations etc. that illustrate different optical effects of special relativity.
Does anyone have any good sites or possibly their own explanation that can assist me with my understanding?
I'll try to give my explanation/interpretation of the visual effects and I would appreciate any feedback on mistakes or gaps in my knowledge.
My explanations-
Terrell Rotation:
At any given moment, all light being received by the observer has reached the observer at the same time. In order for all light from different sources to arrive at the same time and Einstein's second postulate of special relativity to hold true, the light would have left different sources at different times. Therefore, light from a source at a greater distance would have subsequently left the source earlier to arrive at the same time as light leaving a source at a shorter distance.
Objects that are viewed on an angle from an observer traveling at relativistic speeds appear to rotate as a time lag exists between light leaving the further points of the object and when light leaves the closer points of the object. As the object moves or is perceived to move at a relativistic speed, the light sources do not line up with the true shape of the object. This results in a rotated visual distortion of passing objects to the observer.
Doppler Effect:
The Doppler effect explains shifts in the observed wavelengths of light seen by an observer traveling at relativistic speeds. As an observer approaches a light source, the observed wavelength of light will be compressed and they will see the oncoming light with a higher frequency, causing a blue-shift towards the shorter wavelength side of the spectrum. Light from receding sources will undergo rarefaction as the waves are being emitted in the opposite direction of motion. To an observer, a red-shift is seen as the wavelength of light increases and the frequency decreases.
A side note: If the Doppler effect is an optical effect, am I correct in saying that a blue-shift does not mean that you are seeing more energetic light, but just a visual effect of light that appears to be at a higher frequency? In other words, does it mean that blue-shift light has more energy?
Angular Compression (This confuses me.)
I've seen the diagrams of angular compression and a few visual animations but unfortunately our teacher didn't cover the cause of it very clearly. I've heard the aberration of rain comparison but I just can't understand how rain that appears angled to an observer in motion is comparable to an observer at relativistic speeds that can see light from almost 360 degrees around him in his center field of vision.
I'm sorry if I've rambled on, but I've needed a bit of space to try and lay out my thoughts and think about what I know and don't know.
Thanks.