11 Jan '18 18:49>
Can someone explain the Relativistic Doppler Effect to me in the most simple way possible? Particularly the time dilation aspect of it.
Originally posted by @metal-brainWhat specific question about time dilation do you have? How it is derived maybe? Perhaps we can learn together.
Can someone explain the Relativistic Doppler Effect to me in the most simple way possible? Particularly the time dilation aspect of it.
Originally posted by @metal-brainT1=T/(1-v^2/C^2)^0.5 is the dilation part, If you do the math you see at 0.9C the time dilates about 2.4 to one, that is where we on Earth see 2.4 years go by, in the spacecraft doing 0.9C only 1 year goes by on board and that is real time to them, if 24 years go by on Earth only 10 years goes by in the ship and if they come back home the crew will be 10 years younger than say their twin on Earth. It's a real time shift. T is Earth time and T1 is shipboard time.
Can someone explain the Relativistic Doppler Effect to me in the most simple way possible? Particularly the time dilation aspect of it.
Originally posted by @joe-shmoSince c is constant (more or less) how is there a Doppler Effect? How does the wavelength change?
What specific question about time dilation do you have? How it is derived maybe? Perhaps we can learn together.
Originally posted by @sonhouseThat doesn't explain why wavelength changes.
T1=T/(1-v^2/C^2)^0.5 is the dilation part, If you do the math you see at 0.9C the time dilates about 2.4 to one, that is where we on Earth see 2.4 years go by, in the spacecraft doing 0.9C only 1 year goes by on board and that is real time to them, if 24 years go by on Earth only 10 years goes by in the ship and if they come back home the crew will be 10 y ...[text shortened]... so they effectively (as far as their clocks are concerned) have gone 7 times the speed of light.
Originally posted by @metal-brainIt falls out of some surprisingly simple trigonometry. Pretend you are on a train moving with constant velocity "v" and your back is against a wall. There is a mirror on the wall opposite to you. You turn on a flashlight aimed at the mirror. The time the beam takes to reach back to you from your perspective inside the moving train is given by:
Since c is constant (more or less) how is there a Doppler Effect? How does the wavelength change?
Originally posted by @metal-brainHere's an explanation:
That doesn't explain why wavelength changes.
Originally posted by @kazetnagorraThat was the first website I looked at. It didn't help me understand at all. It says it involves time dilation but doesn't explain why.
Here's an explanation:
https://en.wikipedia.org/wiki/Relativistic_Doppler_effect
Originally posted by @metal-brainThe wavelength change arises from λ=c / f and the fact that c is equal in every frame of reference which gives the following relationship.
That was the first website I looked at. It didn't help me understand at all. It says it involves time dilation but doesn't explain why.
Comparing it to a baseball player or train is not helpful to me. The speed of sound is not constant like light is. The train is irrelevant. Why does a star orbiting around a black hole or another star shift from re ...[text shortened]... aberration have to do with it? Wikipedia does a horrible job of explaining it. Pathetic really.
Originally posted by @joe-shmoAll you did was point out the inverse relationship between wavelength and frequency. I am already aware of that. You have not helped, but thanks for trying.
The wavelength change arises from λ=c / f and the fact that c is equal in every frame of reference which gives the following relationship.
λ * f = λ' * f '
λ is the wavelength , and f is the frequency of the light with respect to the person moving with the train in my example above. λ' and f ' are the same quantities in the reference frame of th ...[text shortened]... λ = 1/ √ ( 1 - ( v / c ) ² ) * λ
so as v → c , λ' → ∞
That is the wavelength increases.
Originally posted by @metal-brainYou know how doppler works in audio frequencies, right? You move into a sound and you will hear the frequency go up, wavelength go down and if you move away from the sound the frequency goes down and wavelength goes up? APPARENT frequency, not actual frequency, but it would be able to be picked up and recorded on instruments like microphones, you hear the sound change when a train goes by tooting its horn?
All you did was point out the inverse relationship between wavelength and frequency. I am already aware of that. You have not helped, but thanks for trying.
Originally posted by @metal-brainWell, I'm sorry to hear that. However, I do not believe you are sincere in your attempts to understand. How do you expect to understand the warping of space-time without any road map? ( i.e. equations of special relativity ) These are not phenomenon in which we have any standard sense of in our non-relativistic perspectives. For instance while I was trying to reconcile "Blue Shift" (the star coming at you) with the equation I provided above I realized the equation above could not be correct. There needed to be a term to account for velocity ( speed and direction ). The relation I provided was not capable of providing that ( it failed when trying to explain "Blue Shift" ) so I was forced to investigate further. I found that actual relationship for t' is not what I or sonhouse wrote.
All you did was point out the inverse relationship between wavelength and frequency. I am already aware of that. You have not helped, but thanks for trying.
Originally posted by @joe-shmoHow did the V/C^2 function disappear? So in relativistic doppler, v is plus for approaching an emitter and minus for leaving an emitter? Does the equation work if v is zero?
Well, I'm sorry to hear that. However, I do not believe you are sincere in your attempts to understand. How do you expect to understand the warping of space-time without any road map? ( i.e. equations of special relativity ) These are not phenomenon in which we have any standard sense of in our non-relativistic perspectives. For instance while I was tr ...[text shortened]... ophisticated the math ( the language through which it is understood) required is to describe it.
Originally posted by @metal-brainexactly what doesn't explain why 'wavelength changes'?
That doesn't explain why wavelength changes.
Originally posted by @sonhouse"How did the (V/C)^2 function disappear?"
How did the V/C^2 function disappear? So in relativistic doppler, v is plus for approaching an emitter and minus for leaving an emitter? Does the equation work if v is zero?