# Why is the speed of light the speed of light?

**URL:** <https://boards.straightdope.com/t/why-is-the-speed-of-light-the-speed-of-light/575051>\
**Category:** Factual Questions\
**Created:** [March 17, 2011, 6:46pm UTC](https://boards.straightdope.com/t/why-is-the-speed-of-light-the-speed-of-light/575051 "2011-03-17T18:46:16Z")\
**Posts on this page:** 1\
**Showing post:** 36

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**Author:** ![Ring](https://avatars.discourse-cdn.com/v4/letter/r/6a8cbe/32.png) [@Ring](https://boards.straightdope.com/u/Ring)\
**Post date:** [March 18, 2011, 8:45pm UTC](https://boards.straightdope.com/t/why-is-the-speed-of-light-the-speed-of-light/575051/36 "2011-03-18T20:45:31Z")

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> [@Exapno\_Mapcase](#):
>
> Mass is energy…

**Exapno** I’m surprised at you. You know that statement is not true. Don’t you remember a previous thread where myself, **Stranger** and **Chronos** all explained why isn’t true.

Mass and energy are not _things_ they’re properties of a system, and one cannot be converted into the other.

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