Undergrad Speed of light and speed of sound both constant

[freshnfree]

What exactly do you mean by GPS is doing the second one? Do you mean that GPS is the equivalent of an experiment where you have an observer moving relative to the medium in which there is the source of a beam of light? If that is the case, could you please be more specific in the details.

 

[freshnfree]

This discussion has evolved but it is still in essence comparing light and sound waves. I realized my mistake when I said that the speed of sound would be the same in any situation. It wouldn't if the observer was moving relative to the medium of the sound wave.
So have there been any other experiments which actually have a moving observer to the light source, because if not, I don't think it has been conclusively proven that the speed of light is constant.

I may sound like a novice because I have made some errors, but strangely I knew when I said that the speed of sound was always constant that it was wrong. I still said it because in my mind I was trying to figure something out and that is sometimes how it works. I am not an expert either but I did study physics at high school and first year university. Then I switched to computing science. In that time you do learn the basic fundamental principles of science and I feel that sometimes they are getting broached.
It has been a number of years now when I have felt that something wasn't right so this is not just a fly by night thought.

 

[Vanadium 50]

1. The fact that you don't understand something does not mean nobody does, or that it is wrong.
2. PF is not the place for challenges to conventional physics. That's what the journals are for.
3. If you want to convince people that conventional physics is incorrect, making mistakes when discussing it is not the way to do it.

 

[Drakkith]

So have there been any other experiments which actually have a moving observer to the light source, because if not, I don't think it has been conclusively proven that the speed of light is constant.

Yes, there is an easily observable redshift and blueshift in various astronomical signals (pulsars, CMB, spacecraft , etc) which matches up perfectly, as predicted by SR and GR, with the Earth's orbital motion around the Sun.

 

[Nugatory]

What exactly do you mean by GPS is doing the second one? Do you mean that GPS is the equivalent of an experiment where you have an observer moving relative to the medium in which there is the source of a beam of light? If that is the case, could you please be more specific in the details.

All the GPS satellites are moving relative to one another and the surface of the Earth while continuously exchanging light (at radio wavelengths) signals. Furthermore, different points on the surface of the Earth are moving in different directions at different speeds (because of the Earth's rotation). GPS positions are calculated using a constant speed of light, and would be way off if the motion of either the transmitters or receivers affected the speed of light.

 

[Nugatory]

So have there been any other experiments which actually have a moving observer to the light source, because if not, I don't think it has been conclusively proven that the speed of light is constant.

There Is a sticky thread at the top of this forum on experimental support for relativity: https://www.physicsforums.com/threads/faq-experimental-basis-of-special-relativity.229034/

You want the section on tests of light speed from a moving source.

 

[Herman Trivilino]

This discussion has evolved but it is still in essence comparing light and sound waves.

In the scenario you described, the sound from a fog horn is emitted from a ship that is moving towards an observer on shore. The speed of the sound waves is indeed unaffected by the motion of the ship, but I asked you what speed you'd measure for that sound wave if you were moving from the ship towards the observer.

You didn't answer, but it's clear from what you've already said that you know you'd measure a speed less than the speed measured by the observer on shore.

Now, to answer the question you asked when you started this thread, imagine the same scenario, but this time with a beam of light instead of a sound wave. Both you and the observer on shore would measure the same value for the speed of that light beam. That is the reason that Einstein's theory of relativity differs significantly from the theory of relativity that preceded it.

 

[freshnfree]

1. The fact that you don't understand something does not mean nobody does, or that it is wrong.
2. PF is not the place for challenges to conventional physics. That's what the journals are for.
3. If you want to convince people that conventional physics is incorrect, making mistakes when discussing it is not the way to do it.

I would have a thought a forum was a very good place to make a challenge. Making mistakes is part of learning. It is not a problem to make a mistake, the problem is when the mistake is never corrected because it has been around forever and is therefore thought not to be a mistake. It was 6 years ago that my mind no longer accepted that time dilation was possible. It took my mind six years to even think about challenging that the speed of light was not constant because that's how powerful the idea was in our society. Yes, I have challenged something which was thought to be set in stone and my hands were shaking as I challenged it. It appears that my challenge is not accepted by the people on this forum. So be it.

 

[Drakkith]

I would have a thought a forum was a very good place to make a challenge.

Not this forum. Per PF Terms and Rules:

Mission Statement:

Our mission is to provide a place for people (whether students, professional scientists, or others interested in science) to learn and discuss science as it is currently generally understood and practiced by the professional scientific community. As our name suggests, our main focus is on physics, but we also have forums for most other academic areas including engineering, chemistry, biology, social sciences, etc.

If you are not here to learn about mainstream science, then you have come to the wrong forum. If you wish to challenge a theory used by mainstream science, then do so in scientific journals where such discussion belongs.

It was 6 years ago that my mind no longer accepted that time dilation was possible.

This is nonsense. Time dilation is not only possible, it is observed every single day in experiments around the world. Various technologies like the GPS system and particle accelerators have to be designed specifically to account for time dilation. To say that time dilation is extremely well supported by evidence would be a gross understatement. Modern physics, which predicts the behavior of nature to an absurd degree of accuracy, would literally not make sense without it.

Since you've admitted that your purpose here is not to learn, but to challenge, I am locking this thread.