How Does the Light Barrier Differ from the Doppler Effect?

My limited understanding of redshift of light would not contradict the doppler effect in the frequency of sound.

redshift and the - Curious About Astronomy? Ask an ...

With acoustic waves, if you are moving toward the source of a tone you would measure a faster speed for the sound wave and a higher pitch than someone who was stationary with respect to the source. Likewise someone moving away from the source of a tone would measure a slower speed of sound and a lower tone.

For light only the frequency (or wavelength) changes; the speed of light is always measured as the same value. (The caveat, of course, is the speed of light being measured is the speed in a vacuum.)

I took quantum mechanics back in the early 80's. I believe that the Michelson Morley experiment interpretation, was in error. If you read the history of how they thought the "either" worked (in 1888), any matter (like the earth) flowed through it, as they thought it like water, where it flowed around the solid object. Then in the same class they explained that Lorentz contraction results in the inability to measure the relative motion of light or matter through this either.

I think this introduced the biggest paradigm lock on figuring out a unified physics.

Or as Abe Lincoln said, I just removed all doubt.

What an interesting and oft asked question, let's dig down....oh, already we've hit bottom....It's rather simple, the stretching or contracting of the wave varies the wave length, and thus the perceived color....light is pure energy, sound is a reaction of mass disturbance...

"The speed of sound in an ideal gas is independent of frequency, but does vary slightly with frequency in a real gas. It is proportional to the square root of the absolute temperature, but is independent of pressure or density for a given ideal gas. Sound speed in air varies slightly with pressure only because air is not quite an ideal gas. In addition, for different gases, the speed of sound is inversely proportional to the mean molecular weight of the gas, and is affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is a compression wave."

"The speed of sound is variable and depends on the properties of the substance through which the wave is travelling. In solids, the speed of transverse (or shear) waves depend on the shear deformation under shear stress (called the shear modulus), and the density of the medium. Longitudinal (or compression) waves in solids depend on the same two factors with the addition of a dependence on compressibility.

In fluids, only the medium's compressibility and density are the important factors, since fluids do not tolerate shear stresses. In heterogeneous fluids, such as a liquid filled with gas bubbles, the density of the liquid and the compressibility of the gas affect the speed of sound in an additive manner, as demonstrated in the hot chocolate effect."

"In the Earth's atmosphere, the chief factor affecting the speed of sound is the temperature. "

https://en.wikipedia.org/wiki/Redshift

https://en.wikipedia.org/wiki/Speed_of_sound

Guys I obviously came nowhere near to making my question clear. Let's forget about all the little details about the Doppler effect. They are not important to my question. Let's go back to fundamentals. Air is a medium for sound. Don't worry about the temperature or pressure, we'll just assume our sound wave is travelling through idealized air at a maximum speed of 750 mph. Now, if you're driving your car and blaring your horn at a pedestrian, the sound pitch goes higher as you approach him and lower as you pass and pull away from him. However, correct me if I'm wrong, the speed of sound is constant at 750mph no matter how fast you're moving or how fast the pedestrian is moving. However, if a wind is blowing, it will affect the speed of sound. I believe the Michaelson-Morley experiment was to try to find the medium for light which they called ether and whether there was an ether wind that they could measure affecting the speed of light. The earth's movement through the ether would have created an ether wind on the earth's face but the earth's movement would not have created a wind that would have affected the speed of light through space. So far I can't see the difference between how light behaves and how sound behaves except that light has no medium. And if there is no difference, how did Einstein make the jump that in order to maintain the constancy of the speed of light relative to all other motion, time and space would have to be warped.

Could you restate the question clearly?

First of all I think aether is an archaic term that has no relevance in modern science...

No, you're wrong.

You're stuck on the 'known' speed of sound in air at sea level (known to be about 770 mph) between an emitter and a detector that are static with respect to each other. But if an observer actually tries to measure the speed of sound, then the motion of the observer to or from the source will affect the speed the observer measures. As I said in my previous post, if there is a source emitting a tone and I am moving toward that tone the speed I measure will be faster than 770 mph. Likewise, if I am moving away from the source I'd measure a slower speed.

Go to this link http://hyperphysics.phy-astr.gsu.edu/hbase/sound/dopp.html It clearly states that the speed of sound is not affected by the speed of the source or receiver.

No response? Did you try googling speed of sound and doppler effect? Do you still think I'm wrong?

You keep missing the point. Yes, the speed on sound in air is the same regardless of the speed of the source or the observer.

BUT suppose you didn't already know the speed of sound or the pitch P of the sound being emitted. As you approach a source at velocity v you would measure the speed of sound as 770mph + v. And you'd record a pitch P' which is higher than the pitch P heard by someone stationary (at rest in the emitter's reference frame).

That doesn't happen for the speed of light. For the speed of light regardless of your speed v, you will always measure a speed of light c (the same for you or for a person in the emitter's reference frame). You will, however, measure a frequency f' which is higher than the frequency measured by someone stationary with the emitter (at rest in the emitter's reference frame).

.

I'm trying to understand your reply. Velocity is distance over time. So if you're 770 miles away, you'll hear the sound in 1 hour. But if you're moving towards the source at the speed of sound and you're 770 miles away when the sound begins, you'll hear the sound in half an hour at the halfway point. The sound has moved half the distance in half the time so it is still 770 mph, totally unchanged by your velocity towards the sound. So how are you measuring the speed of sound at 770+v mph? You're only measuring the frequency increase due to the doppler effect but the speed of sound is unchanged. The speed of light would give you the same result. Please watch the youtube video I mentioned.

Here's a diagram.

That's not a speed, it's a frequency the rocket plane is measuring.

Okay, you're hopeless. I'm done here.

Not quite hopeless...

I don't think either one of you wants to agree, but maybe slightly less on your part.

He is referencing the actual "speed of sound"...not the perceived frequency of the sound received. Just as the perceived speed of light receding appears red...the light is not moving more slowly than the speed of light.

The color of the speed is perceived differently. If you moved towards the source of light at the speed of light it would appear at its true color, not shifted towards red.

It is rather rude to blare a horn at a pedestrian. Remember, pedestrians have right of way on a road system and motor vehicle users are only licensed. If this is inconceivable, knock one over and see how the police, the insurance company and the driver licensing authority repsond.

The Michaelson-Morley experiment didn't lead to the theory of relativity, they looked for the preferred direction and were surprised to find there wasn't one. That led to the support of ditching the æther, and thus the support of relativity. It confirms that light has the same speed in all directions, no matter that you are traveling in just one. Einstein got there independently, he realized that the æther was not necessary and that there could no be a preferred direction because that would lead to a preferred place, a place at the center of the universe.

Whether the experiment directly influenced Einstein or not, it still supports the contention that the speed of light is independent of the speed of the source or the speed of the receiver. This would not have been true if the experiment had found an ether wind or preferred direction as you state. So this discounts the existence of ether. Not sure why because the ether could have been at zero velocity with no wind at all and we could have measured all velocities in relation to the speed of the ether which could have been zero. Instead we could measure all velocities in relation to the speed of light which is always the same regardless of relative velocities. But I digress, that was just an observation.

My question still is how does the behavior of light, having a constant speed that is always measured the same regardless of the speed of the source or observer, differ from the behavior of sound in still air which is also always measured the same regardless of the speed of the source or observer. If you can tell me the difference, then maybe I could understand how the results of the experiment support that some uniqueness in the behavior of light, different from the behavior of other waves, could lead one to understand that time and space must themselves bend to support the constancy of the speed of light.

"So this discounts the existence of ether. Not sure why because the ether could have been at zero velocity with no wind at all and we could have measured all velocities in relation to the speed of the ether which could have been zero"

If the ether had been at zero velocity, in all directions, the point at which this measurement was taken would be the center of the universe. The Earth, the Solar System, the Milky Way and yes, the Universe would all be revolving about, or moving to or from, that place. That is more difficult than the universe of Aristotle and Ptolemy which was centered on Earth, not a point on its surface.

I don't really want to veer off on a debate that has nothing to do with my question. I don't care about the non-existent ether or it's nature. To me the ether would have been akin to a large lake on which the universe floated. You wouldn't have to know where the center of the lake was in order to measure relative velocity, you could measure your relative velocity to the water by sticking your speedometer directly under your boat. Anyway, I don't care about this or any other niggling details because they have no relevance to my question. Also the fact that sound can't be bent by gravity and those other details the other guy mentioned also have no relevance. If my question is not clear, which it doesn't seem to be, could someone rephrase it for me? I want to know if the specific nature of light, the one where light speed is not relative to source or receiver, is no different to the nature of the speed of sound in air, the one where sound speed is not relative to source or receiver as it is in the doppler effect, how did the Michaelson-Morley experiment show that the only way the particular nature of light speed, the one where light speed is not relative to source or receiver and is always constant, could be explained in that time and space must not be constant. If the experiment does not lead to that conclusion, how did Einstein manage to do it. Where's that guy Jorrie or Jordaan who wrote Relativity 4 Engineers, he would know the answer.

The argument is that if no point in the universe is favored, if none is the center, then they are all equal and they all would have to measure the same speed for light if there is to be a system of physical laws.

I still don't get what that has to do with my question.

If the speed of light is constant in space, isn't that an absolute motion to which everything else is just relatively slower?

No, the speed of light is not a constant in space. It is constant relative to the person seeing it. That's why the theory is called relativity. Other things are also relative to the person viewing it. Time, distance, mass and simultaneity all differ depending on the reference frame of the observer.

So you're saying the speed of light is not a constant but varies relative to each observer? Ok, I thought I was on a physics forum but evidently I'm mistaken. It's been years since I've been here but there used to be an entire section on relativity. Is that gone now?

This is an engineering forum. Before you try engaging with physicists, I suggest you start with the basics:

http://en.wikipedia.org/wiki/Theory_of_relativity

My bad. I'll try to find a physics forum. Are there any engineers on this forum?

You show me an engineer that understands Relativity and I get a physicist to build my house!

The issue is that the speed of light is fixed in vacuum and it is the absolute maximum velocity possible for anything.

Einstein's theory leads to this equation for summing two collinear velocities:

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/einvel2.html

What are you trying to get out of it?

My head is circling after reading all the gentlemen talking about it but still can't get any thing worthwhile.

Regards;

Nadeem

Does the speeds of sound and light depend on gravity or electrical/magnetic/IR/UV fields?. Can light be bent by electric/magnetic fields?.

Insignificant relevance to my question.

Well, maybe light can't be bent, but it can certainly be twisted under the influence of a magnetic field, this proves that they're related.

Yeah, I know, nothing to do with the subject, I just rememberd the Faraday effect.

Regards

Oh lord, someone out there who understands relativity please help me.

Common, you did ask and can't handle the answer?

That's an answer but do you think it's the right answer? I have a feeling you have no idea.

You lose me here. No I have no idea, but I am not the one that asked a question! I gave up trying to understand this long ago. The problem as you will find is in the receiving end. Its not the one that can not explain it, but it is the one that does not understand it. I have fun now with lesser problems than relativity, which is challanging enough for my small brain to work it out.

Do I think it is the right answer? Well its long enough to try to explain something from a person that seems to have the knowledge required to understand this with the will to help you. I took the liberty to mark it a GA so lets leave it there. Its a good answer.

May I frame this? It not only explains relativity perfectly to me but it explains every question I've ever had about every aspect of existence. Thank you. I've always measured answers by quality and I've had it all wrong. It's the quantity of answer that matters. It's been a slice, now I'm just going to back away, slowly.

Apparently, you will know the right answer when you see it.Therefor,you must already have the answer,so please enlighten everyone with the correct answer.Or are you seeking an answer that will support your pet theory, and if the answers do not agree,then you keep looking?

You will not find YOUR answer here,because the contributors to this forum have tried diligently to break it down into a relative Pablum consistency to make it easy for you to digest.

I think they have been very patient,and you have been very obstinate.

I will not even attempt to try to explain it any further.

Perhaps you should go back to Gerber #1(relatively speaking) and work your way up to solids.

It is good to challenge the status quo,but it pays to understand thoroughly what it is that you are opposing before you begin.

Come back when you understand general relativity,and special relativity,then present a challenge worthwhile of a thoughtful person.

I am looking forward to your presentation in the future.

That's an answer but do you think it's the right answer?

Did you try to get away with your feelings, then it did not work!

Or was that the doppler effect?

There is a relativity section here, and it run by Jorrie. He has an E-book linked to his blog. You are capable of searching for it. Please note that he doesn't care for trolls, but try your luck anyway.

Really? You consider me a troll. You think it's a personal insult to someone when you disagree with them. Anyway Jorrie was the guy I was looking for. I didn't see that relativity section so I wrote him and bought his book (tough read so far). He said he's not active here anymore and he gave me another link and I will go there once I'm done here; if that's ok, or not, with you.

You certainly are a troll when you have been given the correct answers and them mark everybody of topic that doesn't agree with you. Please go to that link now.

<unsubscribe>

C'mon, you have no idea if they're the correct answers or not. I say they aren't. Attack my arguments, not me personally. That's what trolling is.

.

"Canary, your post is essentially correct, but there are a few things that are not strictly correct."

Thanks for the corrections, Jorrie. Also, I think I focused on time dilation and space contraction because that was how I was first introduced to relativity, in the 70s, and only later learned about the effects on simultaneity as the answer to some apparent conflicts, so simulataneity seemed secondary to the basic concept. Interesting that it is now considered primary and the others are considered secondary. They got all the attention in the popular press.

I thought that introducing simultaneity into the discussion would only add to the confusion, but now I see that is a more elegant way of introducing the constancy of c than my explanation.

You come on here asking for demanding answers on your terms. When it is not served up in such a manner as to inch its way through your convoluted brain, you respond unpleasantly.

You are the supplicant here, we are not.

Signing off.

Sound is mechanical energy, it is transmitted molecule to molecule, no molecules=no sound.

Light, a form electromagnetic energy (e.e.) is different. While e.e. can travel through wire, waveguide and fiber optic cable, a medium does not seem to be required. As the e.e. increases in frequency different radiation properties emerge. At DC, only the magnetic portion is radiated, at the extreme high end, more particle properties are evident. As for the Doppler effect, someone else will have to answer if the frequency is shifted or is the "wave" compressed? The difference would be similar to FM modulation vs Phase Modulation. An FM radio will detect both, but they in fact are quite different.

I already stated in my 1st post that light does not need a medium whereas sound does. Does not answer my question.

Maybe it does and you can not see it!

Yay! Thanks for that. I didn't think the physical/electromagnetic theory was going to ever be presented directly.

Of course, I came to the party late...

It appears that someone here just likes ARGUMENTS - not really looking for an answer....

THIS IS NOT THE PURPOSE OF THIS FORUM.....!

"If he had filmed 2 pulses going in opposite directions, space and time would not have altered to prevent them from receding from each other at twice the speed of light."

You are right but the above has nothing to do with relativity because you are considering just how quickly are "moving" to each other two points in space (the fronts of the 2 pulses). I can give you another example: consider two strong lasers that are 1km from each other and are intersecting their beams on the same point on the Moon; suddenly (in a fraction of a second) their position is changed so that they almost point to each other (their intersecting point is now very close to the surface of the Earth at 0.5km from each other). So, if you consider the speed of the intersecting point (some 384000km in a fraction of a second) you can obtain "speeds" that can be even millions of times bigger that "c". But relativity applies only to speeds of "real objects" and they are limited to "c".

Regarding the understanding of relativity, it's not easy. If you consider for example understanding temperature you can say it's well understood - we know "how" and also "why". Understanding gravity is different - we know "how" but we don't know "why". But for relativity we know "how", we have no idea "why" and we also have the problem that "how" is contrary to our "common sense", so even "how" is not in fact fully understood and accepted by our mind. I have spent many hours to fully understand "how" and I have now my own "theory" that explains it very well, so that my "common sense" is fully satisfied. If you are interested in this I can try to share with you some concepts (although a full explanation would probably need a small book - which I have now only in my head).

The universe has no obligation to satisfy your common sense. Relativity was opposed by other scientists because it did not satisfy their common sense, and yet now it is universally accepted by physicists as the way things work. Not because there is any high priest telling them so, but because the data proves it. I was not drawing any conclusions in my previous post. I was simply laying out what the facts are that physicists have accepted about how light works. It does not satisfy anybody's common sense. It is still the best description of how the universe works, even if nobody actually knows why it works that way.

You haven't cited these "mountains of evidence on google," and I sincerely doubt that you have found a single piece of evidence that contradicts what I said in my long post. The Raskar video does not prove anything about relativity. It simply shows what a single extremely short pulse of light would look like if you could actually watch it proceed, by taking many pictures of many pulses, each one slightly later than the previous one.

You admit that you don't understand relativity, but that you would understand it if only someone would answer your question about the Doppler effect. What you are actually saying is that you want someone on the engineering forum to please confirm that all the physicists for the past century were wrong about the speed of light, so that you don't have to tolerate the tremendous discomfort you feel at the idea that the universe does not conform to your common sense.

I have to say that if you are lucky, you will be disappointed. If you are not lucky, you will persist in believing that your common sense is better than Einstein's training and his lifetime of looking at actual data, and every physicist since him. Also if you are not lucky, you will continue to think will that people will want to discuss things with you even when you insult them rather than by present any actual evidence. It is a stretch for me to even write this post, after your reaction to my previous one.

And if you think relativity is difficult, wait till you get to quantum physics.

You may have your favorite answer in your head and that is the reason you are rejecting all the answers. Please enlighten us and tell us for our edification as to what the truth is?

Nadeem

I did over and over again. I'm saying there is no difference in behavior between a sound wave and a light wave in a still medium (no medium for light). The observed velocity of the wave is independent of the motion of source or observer. Once we get that established, I want to understand why, if light behaves just like any wave (except for the medium part) how does its "strange" behavior lead to the theory of relativity.

I'm saying there is no difference in behavior between a sound wave and a light wave in a still medium (no medium for light). The observed velocity of the wave is independent of the motion of source or observer.

Wrong,

If you are at the source of a sound wave and then accelerate in a straight line to 75% of the speed of sound, the sound wave will be travelling away from you at 25% the speed of sound in the direction you accelerated and 175% in the opposite direction.

If you are at light source and accelerate in a straight line to 75% the speed of light. The light will still be travelling away from you at the speed of light in all directions.

It is very difficult to "wrap ones head around" this concept but, that's what has been proven.

Hmmm you're making me think. So if I'm both the source and observer that's where the difference is between sound and light. So if you're in a jet plane at mach1, the speed of your sound relative to you is 0 in front of you and mach2 behind you. However for an observer in front of you, the source's speed does not change the speed of sound, only the pitch. Light does not work this way if the source and observer are the same person. Light speed is the same in all directions. Ok, that's the answer I wanted to hear under my terms. I just have to wrap my head around it now.

I think its the other way around. You make Mach 2 and the sound you make is at Mach 1 which is Mach 1 behind. It still has a speed right!

Sound before you is I would say Mach -1 - pure arithmetic of course.

It sounds like you understand sound.

Think about this regarding light:

You are in a glass train moving at 50% the speed of light. You have a flashlight, a mirror on the ceiling, and a light detector on the floor. You aim the flashlight at the mirror, turn it on, and the detector indicates light. You saw the light beam travel straight up then straight down hitting the detector.

I am standing on the ground watching you go by. When you flash the light, due to your velocity, I see a light beam travel at a forward angle up to the ceiling (it had to angle from my perspective due to the speed of the ceiling) and down at a forward angle to the detector.

You saw the light beam travel a distance x. I saw the beam travel a distance much more than x. We both saw the light hit the detector at the same time. Therefore the speed of light is the same for someone moving at 50% the speed of light as someone at rest.

Since I report a longer beam, and we both saw the detector struck at the same time, time was running slower for you than for me.

"You saw the light beam travel a distance x. I saw the beam travel a distance much more than x. We both saw the light hit the detector at the same time. Therefore the speed of light is the same for someone moving at 50% the speed of light as someone at rest."

WJMFIRE, I know this is a (good?) common popular explanation for the constancy of the speed of light for all observers, but beware: it is full of holes. The problem is that you and the train traveler do not have the same definition of time, or rather of simultaneity. You do not know which clock is "slower" than which, because this effect is complementary - it depends on who is looking at what clock. Further, you need multiple observers with clocks synchronized per inertial frame in order to perform such an observation.

The modern version is that you cannot measure the one-way speed of light at all, simply because you have to use that one-way speed to synchronize the two clocks you need. The outcome is then a given. We measure the two-way speed with one clock and then just take it to have the same speed both ways. This warrants deeper discussion than what I have time for presently, but I will try to prepare a Blog post to address some of the latest insights.

-J

Thanks for that Jorrie.

I am looking forward to your blog.

My knowledge is very rudimentary with regard to this stuff, but i love it.

Thank you Jorrie, I will think hard on this. This was the first couple of pages of your book and I was already having trouble. I guess this relates to Einstein's mirror. It's why he would still be able to see his reflection if he was in a car travelling at the speed of light.

I can see the answer's here but I'm like a python on a hippo; there's a good meal here if only I could get my head around it. I guess it's too much to ask why light behaves this way and then I have to understand the other pieces of the puzzle especially the relativity of simultaneity. This could take years.

"This could take years".

Then that would rule out simultaneity.

"This was the first couple of pages of your book and I was already having trouble. "

Keep it up, because once you have absorbed chapter 2 of the little book, you will be able to work out all the answers that you asked for here.

Thanks for posting your explanation. I would be very curious, if you have time, to hear what you think of answer #23, my first attempt to answer the question.

The speed of sound is about 1000 ft/sec in air with respect to the air. If points A and B are 1000 ft apart, an explosion at point A would be heard by an observer at point B about 1 second later and vice versa. If the wind were blowing in the direction A to B, an observer at B would here the sound less than a second later and observer A would hear an explosion at B more than a second later. Measuring the difference in transit time in each direction would allow you to determine the velocity of the wind. A and B could be two airplanes flying at a constant separation and the same argument would hold. This is what the Michaelson-Morley experiment was designed to do with respect to the velocity of light, i.e. measure our speed with respect to the medium (the aether). The result, of course, was that the speed came out zero no matter in which direction it was measured.

If A and B are stationary with respect to each other, the speed of sound as calculated by the transit time is determined by the wind speed, but there is no Doppler shift. A sound wave emitted from A at 1000 hz would be received at B at 1000 hz. If B were approaching A, there would be fewer sound waves "stored" between A and B as time goes on. B would therefor receive sound waves at greater than 1000 per second and the sound would be Doppler shifted upward. So Doppler is only observed when there is relative motion between A and B.

In regards to the light experiment, I think you were referring to this.

http://web.media.mit.edu/~raskar/trillionfps

It's a bit of a trick. You are not seeing a single light pulse, but a series of extremely short exposure pictures of a series of repeating light pulses taken slightly later each time to give the illusion of motion. It is the familiar strobe effect that makes wagon wheels in old western movies appear to turn slowly. I do not think you can infer from watching this movie the speed of the light pulses with respect to each other.

If it's true what you say, then the Raskar video would not be celebrated at all. He wouldn't need all those expensive cameras. He could just film a bunch of time delayed pulses with a normal camera and superimpose them all to give an illusion of pulse propagation. Yes, he is filming multiple pulses so they can register on the camera but the whole purpose of this experiment is to film light speed as it really happens.

If it's true what you say, then the Raskar video would not be celebrated at all.

On the contrary, I think it's extremely impressive. The engineering challenge of capturing images with trillionth second exposure with precision timing is no mean feat. My "bit of a trick" expression was not meant to indicate otherwise, but to describe how it is done, i.e., with repeated laser pulses, capturing each slightly later.

I don't understand this statement then, "I do not think you can infer from watching this movie the speed of the light pulses with respect to each other."

If he's not doctoring the speed of light, if it's actually being represented truthfully in slow motion as 1 femtosecond = 1 sec on film (or something like that), and if relativity is correct that no observer can see real information go faster than the speed of light, then two pulses fired simultaneously past each other (if only he had done that), then, I think, we would have not been able to see the two slow motion pulses separate from each other at twice the speed of light. This is because lightspeed is constant for all inertial frames of reference whether I'm observing from the outside or whether I'm hitching a ride on the tail end of one of those pulses. Yes, I agree that if I was on the tail end of one of those pulses, I'd see the other tail end recede from me at lightspeed and not twice the speed of light. I'd see that because the doppler effect would maintain the constant velocity of the pulse but it would highly red shift it. This just leads back again to my original question. How did the Michaelson Morley experiment show anything other than light behaving as any other wave except that it didn't require a medium.

You are not seeing the speed of light pulses with respect to each other

You are perceiving the light pulses with respect to the camera lens, the internal workings of the camera, your eye, etc.

You cannot be there with the light pulses...at the speed of light...to see how they perceive "each other" with respect to "each other"

So if I'm taking a video of 2 sports cars passing each other, there is no way I can infer how fast, from the video, they're separating from each other? And if one of those cars had a horn and I was on the back of the other car, I wouldn't hear a lower pitch from the horn and the speed of the sound would be altered by the car's relative velocities? I disagree once again.

Are you saying the Doppler shift is the result of altering the speed of sound, and not the compression/then expansion of the wave front?

Nope I'm saying I disagree that the velocities of the cars alter the speed of sound. Anyhoo I got the answer I wanted from Troy36 and Jorrie. The rest on here weren't even close.

A closer analogy would be the wagon wheels on an old western movie. Can you tell how fast the wheel is turning as it appears to move forward and backward due to the stroboscopic effect of the movie projector?

You are watching the speed of light pulses with respect to the camera lens, its internal workings and your eye, etc.,

...not with respect between themselves...

You have to be there...at the speed of light...which you cannot be...

You don't have to be there at the speed of light anymore than I have to be there, at the nanoscale, to design a microchip. We have all sorts of measurement tools to allow us to be anywhere we want. When we are moving away from a star, we can measure its speed of light and see that our velocity or its velocity does not alter the speed of light. Minus the details you're concentrating on, that's exactly like me hitching a ride on the back of a light pulse. Yup, believe it.

From the earth's perspective, certain stars appear to red-shift.

From the perspective of an object with identical motion characteristics to the earth in the same line with that object and referencing that object there would appear to be a blue-shift.

The speed of light between all objects is same.

The perception of the compressed or rarified light waves is different.

Would you like to have another go at this, please:

"From the perspective of an object with identical motion characteristics to the earth in the same line with that object and referencing that object there would appear to be a blue-shift."

Umm...no?

But...how about a picture:

Let me try another tack with you guys. Say you have a baseball pitcher on the back of a flatbed truck listening to the "sweet" sounds of country music. You are on the road facing him with a radar gun as he lets fly a fastball. The pitcher can only pitch 100 mph fastballs. (Don't get caught up in the details.) Your radar gun always measures the speed of the ball at 100 mph plus the speed of the flatbed truck. Now the pitcher picks up an air horn and your gun is set to detect the sound so you can move out of the way in time. If the truck is moving at 770mph, you'll hear the horn just as the truck hits you. It's because the speed of the truck can't push the soundwave any faster than 770 mph. If your radar gun could measure the speed of sound, it would always be 770mph regardless of the speed of the truck. If the pitcher could pitch sound waves, they would go at 770mph regardless of how fast or slow he pitched them. This is the difference between solid objects and energy waves. I contend that sound speed is also constant in any inertial frame of reference so how did that fact not lead to the theory of relativity but the identical behavior in light did.

Oops I forgot one thing. Let's put a flashlight in the pitcher's hand. You will see the same behavior for light as you did for sound. The speed of light through air is not affected by the speed of the truck. This behavior of light spawned the theory of relativity but the identical behavior of sound didn't. Why? I'm not trying to overturn relativity, I'm just trying to understand this one tiny part of it that doesn't make sense to me. In other words trolling.