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Gravity Probe B

Testing Einstein's Universe

Special & General Relativity Questions and Answers

If an object approached the speed of light, would it be transformed into light?

No. Light has what is called 'zero rest mass' and no material body, not even an electron, can approach such a condition. As you accelerate a particle to near the speed of light, its non-zero rest mass would always prevent you from actually attaining light-speed. Also, light consists of oscillating electric and magnetic fields at right angles to each other AND to their direction of travel. No material particle can be made to do this.

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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.