speed of light

Astrophysics / Physics / Relativity

The Curvature of Spacetime

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Abell 2218

Spacetime is curved. We’ve all heard the line. But what does it mean? Well on the largest scales, the curvature of spacetime is abundantly clear as the warped fabric of the universe distorts images of distant objects. The image below is of the Abell 2218 galaxy cluster, taken by the Hubble Space Telescope. The cluster is very massive so it warps the spacetime around it. This warped spacetime acts as a lens so that light light coming from galaxies behind Abell 2218 is spread out much more than it should be. The result is that images of galaxies behind

Physics / Relativity / Science And Math

Rock Me, Einstein — Some Questions on Special and General Relativity

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In 1905 Albert discovered Relativity, in 1906 he invented Rock and Roll ~Yahoo Serious In the last week or two, I’ve gotten several excellent questions on special and general relativity. I’d like to devote this week’s post to presenting and answering those questions. For the sake of anonymity, I will call the people who asked the questions Ms. C and Mr. A. I hope you enjoy! A Question on Special Relativity The first question is by Ms. C, who asked: I’ve read your article “The Speed of Light is Constant.” I’ve… got a question on the speed of light

Physics / Relativity / Science And Math

FTL Part 2: The Universal Speed Limit

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Woody Allen

It is impossible to travel faster than the speed of light, and certainly not desirable, as one’s hat keeps blowing off. ~Woody Allen This is Part Two of a multipart series on faster-than-light travel. This time, I’ll describe why it’s difficult to travel faster than lightspeed. At the end of my last article, I told you that the speed of light is constant, independent of the speed of the observer or the source. If I drive past you at half the speed of light with my headlights blazing, the photons of my headlights will be going past you at