You are here:

# Relativity/Speed of light

Question
why and how is the speed of light constant? Why does not it follows relativity?
Can we see light? if yes,how would it be and what will be it's colour.

Of course we can see light! And relativity correctly predicts it. Why and how are not available to us. That's nature for you and me.

Its colour is different for objects moving with respect to us; that is how we can see how fast a star is moving relative to us, if we know what element causes the light so we can tell how much the colour is changed. Example: if it is sodium emitting the light, we know what the colour would be if it were stationary. If it is shifted a bit, we can measure the color change and calculate its relative speed

We can identify it as sodium light by the spectrum of colours. They have a characteristic pattern of colours even if shifted a bit.

The shift is called the Doppler Effect, which you can hear also when a train goes by. Look it up.

Ben

Relativity

Volunteer

#### Uncle Ben

##### Expertise

I can answer questions regarding Einstein's Theory of Relativity, particularly in Special Relativity. I will not answer homework questions or mathematical problems that require special symbols.

##### Experience

I have taught physics at the college level, undergraduate and graduate, for many years including Special Relativity. I have taught at Johns Hopkins, Case-Western, and MIT. I have also served as a staff member of the Commission on College Physics, which was supported by the National Science Foundation to recommend improvements in the curriculum of college physics departments in the US. I am also the author of a textbook titled Vector Calculus, which was used at MIT in the teaching of electromagnetic theory and relativity. My research interests were mainly in solid state physics, especially the properties of metals at low temperatures. I am listed in the publication known as American Men of Science.

Publications
I have dozens of papers published in the Physical Review and in the American Journal of Physics.

Education/Credentials
I hold a Ph.D. degree in physics from the Johns Hopkins University.

Past/Present Clients
Johns Hopkins University, Case-Western Reserve University, Massachusetts Institute of Technology, Empire State College, Georgetown University, Commission on College Physics, and UNESCO.