If I could provide you with a device to measure the speed of light, and the accuracy can reach 0.01 m/s, what would you do?somega said:I know the amazing thought experiment by Albert Einstein with the two light clocks.
(The observer at the train station has a light clock and the person in the train.)
It's amazing because you can even deduce the formula to calculate how fast the clock in the train goes.
But this experiment requires the knowledge that the speed of light is constant.
(So I personally would never have come to this thought experiment.)
I wonder if there is another thought experiment that shows that the speed of light is constant?
I would point out that you need to update your device to modern standards. The speed of light is now a defined constant, so measuring it is either using an older standard or contains some circular logic.TonyYuan said:If I could provide you with a device to measure the speed of light, and the accuracy can reach 0.01 m/s, what would you do?
As an undergrad I had a lab measuring the time delay of the signals between the photons from e+e- annihilation hitting two opposite detectors before and after moving one of the detectors. The conversation with the professor went something like this:Ibix said:I would point out that you need to update your device to modern standards. The speed of light is now a defined constant, so measuring it is either using an older standard or contains some circular logic.
My device is definitely not only used to output 300000000.0 m / s, it is the most primitive method applied to modern program technology to achieve the measurement of the speed of light.Ibix said:I would point out that you need to update your device to modern standards. The speed of light is now a defined constant, so measuring it is either using an older standard or contains some circular logic.
The meter is defined to be the distance that light in vacuum travels in 1/299792458 seconds, so any device that purports to be measuring the speed of light in vacuum is in fact just calibrating itself.TonyYuan said:My device is definitely not only used to output 300000000.0 m / s, it is the most primitive method applied to modern program technology to achieve the measurement of the speed of light.
TonyYuan said:If I could provide you with a device to measure the speed of light, and the accuracy can reach 0.01 m/s, what would you do?
As pointed out already, this is not correct.TonyYuan said:My device is definitely not only used to output 300000000.0 m / s, it is the most primitive method applied to modern program technology to achieve the measurement of the speed of light.
With a good light speed meter, you can be in the United States, in France, in the Antarctic, at rest, in motion. . . Both can be used to measure the speed of light, and even use it to detect gravitational waves, just like LIGO does.PeterDonis said:Ask you what the point of your question is.
The measurement of the speed of light is a function that everyone can see. But the impact of changes in external conditions on the speed of light is where we focus. Many people tell us that the speed of light is constant. Why not measure it yourself, let the light run with you, and drive with you. Let us see if the speed of light will change.Ibix said:As pointed out already, this is not correct.
The simplest way to measure the speed of light in vacuum is to time how long it takes to travel a known distance. The problem is that distances are measured in meters, or can be converted to meters, and one meter is defined as the distance light travels in 1/299792458 seconds. So your distance measure depends on the defined speed of light, and will return exactly the defined value to your available precision.
Older systems, including earlier SI schemes, define distance in terms of multiples of the length of some object. You can measure the speed of light in such a system, but it is not the modern approach. Such schemes have been supplanted by the modern SI approach because it can be made more precise.
TonyYuan said:With a good light speed meter
TonyYuan said:even use it to detect gravitational waves, just like LIGO does.
TonyYuan said:the impact of changes in external conditions on the speed of light is where we focus. Many people tell us that the speed of light is constant. Why not measure it yourself, let the light run with you, and drive with you. Let us see if the speed of light will change.
The speed of light is measured using a variety of methods, including the use of lasers, interferometers, and astronomical observations. One of the most accurate methods is the use of a Michelson interferometer, which measures the time it takes for light to travel a known distance.
The speed of light is a fundamental constant in physics and is used in many equations to describe the behavior of light and other electromagnetic radiation. Accurate measurements of the speed of light help to validate and refine these theories and have practical applications in fields such as telecommunications and astronomy.
The first accurate measurement of the speed of light was done in the 17th century by Ole Rømer, who used observations of the moons of Jupiter to estimate its speed. Since then, the methods and technology used to measure the speed of light have improved, leading to increasingly precise measurements. Today, the speed of light is defined as exactly 299,792,458 meters per second in a vacuum.
According to the theory of relativity, the speed of light is the maximum speed at which any object can travel. This means that it is not possible for an object with mass to reach or exceed the speed of light. However, there are some theories that suggest the existence of particles, such as tachyons, that may travel faster than light, but these have not been proven.
The speed of light is affected by the medium it travels through. In a vacuum, light travels at its maximum speed of 299,792,458 meters per second. However, in materials such as water or glass, light travels at a slower speed due to interactions with the atoms in the material. This is known as the refractive index, and it is different for each material.