Methods to measure the speed of the light

In summary: Just make sure to check the dates of the last post before commenting on a thread. Anyway, the summary:In summary, the conversation revolved around the methods used to measure the speed of light, specifically focusing on Fizeau's experiments and the tools he used. The topic also touched on the importance of describing experimental setups in physics and the policy of not resurrecting old threads on the forum.
  • #1
honolulu_boy
12
0
Hello,

I would like to know what are the differents methods to measure the speed of the light.

Thanks
:smile:
 
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  • #3
Well I have a problem to understand how Fizeau made his measurements ! What were his tools to measure time ?
 
  • #4
Probably crystals, counting the number of vibrations.
 
  • #5
zhermes said:
Probably crystals, counting the number of vibrations.

How he made the counting ?
 
  • #6
Don't know. Some sort of electronics... maybe piezoelectrics.
 
  • #7
I don't understand why there is always so few indications on experimental setup in Physic
 
  • #9
honolulu_boy said:
I don't understand why there is always so few indications on experimental setup in Physic

The experimental set-ups are generally very well described in the published paper(s) that result from the experiment. This is done so that others can reproduce the experiment, if need be.
 
  • #10
Geezer said:
Didn't Fizeau use some spinning wheel with holes in it?
Good catch Geezer, my apologies---I was thinking about something entirely different. Fizeau's apparatus doesn't need to measure the time explicitly, it drops out of the equations. My bad.
 
  • #11
For God's sake!
Piezoelectrics in 1800's??
Mirrors and spinning wheels and that's all!
 
  • #12
Any reason you felt compelled to mention this after almost 2 years had passed?
 
  • #13
well, if you check my registration date you will see that it is roughly a week. Since then, I have been scrolling down all forums to find topics that interest me the most. Therefore, despite the time that has passed since the last post I wanted to comment.
 
  • #14
e.chaniotakis said:
well, if you check my registration date you will see that it is roughly a week. Since then, I have been scrolling down all forums to find topics that interest me the most. Therefore, despite the time that has passed since the last post I wanted to comment.

It is generally frowned upon to "resurrect" an old thread. If you have a question about the same topic it is usually better to create a new thread instead, as many of the posters in the original thread may be gone now, and a multi-page thread usually gets far fewer looks than a fresh new one.

PF is not your average forum. We try to maintain high standards in our posts, so bumping an old thread simply because you wanted to comment on it is generally not considered to be a good reason.
 
  • #15
I was not aware of this policy! Thank you for mentioning it to me. From now and on it will be done this way.
 
  • #16
e.chaniotakis said:
I was not aware of this policy! Thank you for mentioning it to me. From now and on it will be done this way.

No problem, everyone's got to learn somehow!
 

1. How was the speed of light first measured?

The speed of light was first measured in 1676 by Danish astronomer Ole Rømer. He did this by observing the eclipses of Jupiter's moon, Io, and noting the discrepancies in the timing of the eclipses as Earth moved closer to or farther away from Jupiter in its orbit around the Sun.

2. What is the most accurate method for measuring the speed of light?

The most accurate method for measuring the speed of light is using a laser interferometer. This method involves splitting a laser beam into two paths and then recombining them to create interference patterns, allowing for precise measurement of the speed of light.

3. How does the speed of light change in different mediums?

The speed of light is affected by the medium through which it is traveling. In a vacuum, the speed of light is approximately 299,792,458 meters per second. In other mediums, such as air, water, or glass, the speed of light can be slower or faster depending on the density and refractive index of the medium.

4. Can the speed of light be exceeded?

According to Einstein's theory of relativity, the speed of light is the maximum speed at which all matter and information in the universe can travel. Therefore, it is currently believed that the speed of light cannot be exceeded.

5. How has the measurement of the speed of light evolved over time?

Since Rømer's initial measurement, the speed of light has been measured using various methods and technologies, including rotating mirrors, Fizeau's toothed wheel, and modern-day lasers and interferometers. With advancements in technology, the accuracy of these measurements has greatly improved, allowing for a more precise understanding of the speed of light.

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