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Gravity Probe B

Testing Einstein's Universe

Special & General Relativity Questions and Answers

What objects have we seen traveling near the speed of light either natural or man-made?

We can accelerate individual atoms, protons and electrons to very nearly the speed of light in 'accelerator labs' across the world such as CERN, SLAC, Fermilab. We can detect cosmic ray electrons that naturally have been accelerated to 99.999 percent the speed of light. In deep space, we see jets of plasma being ejected from the cores of galaxies, and in the most spectacular cases, these jets are pointed nearly in our direction so that we see peculiar special relativistic effects that make the plasma look like it is moving faster than the speed of light...but in fact the observations and geometry are consistent with thousands of solar masses of plasma accelerated to 99.9+ percent the speed of light. We do not know how this happens, but at the cores of these galaxies we now know that massive black holes lurk, and some electromagnetic phenomena in their orbiting disks of gas are providing this acceleration. Even on the Sun, in solar flares, we see how particles can get accelerated to very high speeds.

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All answers are provided by Dr. Sten Odenwald (Raytheon STX) for the NASA Astronomy Cafe, part of the NASA Education and Public Outreach program.