pipertripp Yeah I screwed up on that when I made the original slides/recording. I fixed my slide but never replaced the video. Thanks for the reminder.
Is this scenario also valid? You have a light from certain source emitted with given wavelength λ , but the observer is moving to/away relative to the source - would the apparent wavelength (travelling from its source with λ wavelength) change when absorbed by moving detector? Is the light continuously red-shifted because of expansion during its travel, or is it shifted only on emission and detection, because of the source & observer speeds?
Assume we are talking about a distance where red shift due to the expanding universe is not significant so that the Doppler shift is only due to the motion of either the source or the observer. If the observer is moving towards or away from the source, the observer will observe a shifted wavelength and frequency. One way I think about this is to imagine the source is a pitching machine throwing balls at a fixed rate. If you are moving towards the pitching machine, the frequency at which you are hit by balls will increase. If you continuously move away the frequency (the rate will be slower). But to a stationary observer, the rate at which the balls are thrown by the machine and received will not change. So for a stationary source and moving observer, light is shifted on detection but not in emission or during its travel.
I really object to SR using the term "Doppler" to describe the red and blue-shifting of light. Doppler is an effect describing energy in a medium, with sound being able to travel at different speeds in different frames which is how and why Doppler works without breaking the Law of the Conservation of energy. Relativity needs to get it's own version - maybe _Relativity Red and Blue-shifting?_ It still means your theory breaks with the conservation of energy, but at least you will no longer be stinking up real physics (Doppler in sound waves)!
Only thing that confuses me is the fact that Einstein state’s that light is constant so how is the Doppler effect possible with light?????? Please help understand this.
Light moves at a constant speed as you point out. But it turns out to be constant regardless of its wavelength. A blue photon travels just as fast as a red photon, etc. So the only thing that changes in the Doppler effect is the wavelength; the light changes to a new "color" but still travels at c. Hope that helps!
@@LaunchPadAstronomy I have a question then, light moves in light speed relatively to any objects, including light itself. Due to it, it is supposed that any objects relative to light must be at rest. if everything are at rest with comparison to light, how doppler effect occurs?
@@LaunchPadAstronomy Light moves at constant speeds relative to the source only. Your animation is technically incorrect. Because in the source frame you show the light *slowing down* as it moves away from the source. That is, slowing down relative to the source. And the only experimental data on light speed we have to refer to is always where the observer is not moving relative to the source. Ie Michaelson Morley, Lunar ranging ex.etc. And they always show light travelling away from and reflected back to the source at c. Even though the experiment itself (and the earth)is moving at hundreds of kms through space. That’s why these experiments are conducted. To see if light still travels at c even if the experiment and the earth are moving through the cosmos. Some relativists argue that experiments like Ives Stillwell prove that c is constant in the experimental frame even though the source supposedly moves. But if you study the maths of Ives Stillwell you can see they actually used a mathematical formula describing how light travels at c relative to the source only and pretended it was the formula for a relativistic constant speed of light in all frames.!! Yes. Ives Stillwell and others actually falsify their maths to discredit non relativistic theory and falsely credit SR. If you don’t believe me I’ll show you the maths right here on you tube replies.
This video is incorrect. It ignores data from the Michaelson-Morley experiment which showed that light propagates away from a source at c, regardless of the motion of the source through space. That is as the experiment on earth moves around the sun and center of the Milky Way. Yet in this video light is travelling away from the source in the source frame at slower speeds than the speed of light. That is at slower speeds of light relative to the source. This contradicts many experimental observations of light which show that light always moves at c, the speed of light, relative to the source.
I wouldn’t take the animation as gospel as light in front of a source doesn’t get nearly as blue or as red behind the source either. It’s just there to illustrate the concept of Doppler shift. Likewise the animations deliberately slow light speed down so we can see the wave propagation, again just for illustration purposes.
clear and cool animations, thank you my g
Thank you
Thank you this helped with my final
gr8 vdo thanks!
Very nice video and explanation.
What program do you use for your animations?
Thank you very much! This video was an Apple Keynote presentation.
@@LaunchPadAstronomy Well that's convenient, I was afraid it wouldn't run on MacOS!
super
great video!!
Thanks!
Shouldn't the conversion to km/s give you 6.17km/s rather than 617 km/s
pipertripp Yeah I screwed up on that when I made the original slides/recording. I fixed my slide but never replaced the video. Thanks for the reminder.
@@LaunchPadAstronomy if I had a nickel for every time I've made a mistake like that ...
Hi, how could we get to know the axis of motion and direction of the movement of the star? Thanks in advance
I think my latest video might be able to assist you: th-cam.com/video/Ku8EGR6N1MM/w-d-xo.html
Is this scenario also valid?
You have a light from certain source emitted with given wavelength λ , but the observer is moving to/away relative to the source - would the apparent wavelength (travelling from its source with λ wavelength) change when absorbed by moving detector?
Is the light continuously red-shifted because of expansion during its travel, or is it shifted only on emission and detection, because of the source & observer speeds?
Assume we are talking about a distance where red shift due to the expanding universe is not significant so that the Doppler shift is only due to the motion of either the source or the observer. If the observer is moving towards or away from the source, the observer will observe a shifted wavelength and frequency. One way I think about this is to imagine the source is a pitching machine throwing balls at a fixed rate. If you are moving towards the pitching machine, the frequency at which you are hit by balls will increase. If you continuously move away the frequency (the rate will be slower). But to a stationary observer, the rate at which the balls are thrown by the machine and received will not change. So for a stationary source and moving observer, light is shifted on detection but not in emission or during its travel.
I really object to SR using the term "Doppler" to describe the red and blue-shifting of light.
Doppler is an effect describing energy in a medium, with sound being able to travel at different speeds in different frames which is how and why Doppler works without breaking the Law of the Conservation of energy.
Relativity needs to get it's own version - maybe _Relativity Red and Blue-shifting?_ It still means your theory breaks with the conservation of energy, but at least you will no longer be stinking up real physics (Doppler in sound waves)!
Only thing that confuses me is the fact that Einstein state’s that light is constant so how is the Doppler effect possible with light?????? Please help understand this.
Light moves at a constant speed as you point out. But it turns out to be constant regardless of its wavelength. A blue photon travels just as fast as a red photon, etc. So the only thing that changes in the Doppler effect is the wavelength; the light changes to a new "color" but still travels at c. Hope that helps!
Launch Pad Astronomy interesting 🧐. I would love to see a simulated explanation to really illustrate this fact. But yes, this helped. Thanks.
@@LaunchPadAstronomy I have a question then, light moves in light speed relatively to any objects, including light itself. Due to it, it is supposed that any objects relative to light must be at rest. if everything are at rest with comparison to light, how doppler effect occurs?
@@LaunchPadAstronomy Light moves at constant speeds relative to the source only. Your animation is technically incorrect. Because in the source frame you show the light *slowing down* as it moves away from the source. That is, slowing down relative to the source. And the only experimental data on light speed we have to refer to is always where the observer is not moving relative to the source. Ie Michaelson Morley, Lunar ranging ex.etc. And they always show light travelling away from and reflected back to the source at c. Even though the experiment itself (and the earth)is moving at hundreds of kms through space. That’s why these experiments are conducted. To see if light still travels at c even if the experiment and the earth are moving through the cosmos.
Some relativists argue that experiments like Ives Stillwell prove that c is constant in the experimental frame even though the source supposedly moves. But if you study the maths of Ives Stillwell you can see they actually used a mathematical formula describing how light travels at c relative to the source only and pretended it was the formula for a relativistic constant speed of light in all frames.!! Yes. Ives Stillwell and others actually falsify their maths to discredit non relativistic theory and falsely credit SR.
If you don’t believe me I’ll show you the maths right here on you tube replies.
This video is incorrect. It ignores data from the Michaelson-Morley experiment which showed that light propagates away from a source at c, regardless of the motion of the source through space. That is as the experiment on earth moves around the sun and center of the Milky Way. Yet in this video light is travelling away from the source in the source frame at slower speeds than the speed of light. That is at slower speeds of light relative to the source. This contradicts many experimental observations of light which show that light always moves at c, the speed of light, relative to the source.
I wouldn’t take the animation as gospel as light in front of a source doesn’t get nearly as blue or as red behind the source either. It’s just there to illustrate the concept of Doppler shift. Likewise the animations deliberately slow light speed down so we can see the wave propagation, again just for illustration purposes.
If we were sensitive to 5g towers rf this could also apply Right? To find out the direction they come from
You made a math error at the end there , but I assume others have told you by now. Otherwise, excellent video.
What keeps a photon to oscillate for billions of years??? The rabbit of Energizer can go shove its head somewhere... perpetual motion shmmotion...
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