# Relativity for Everyone: Part I: The Speed of Light NEVER Changes!

In this series of articles, I’ll be explaining Einstein’s Theory of Relativity.  I’ll use little to no math.  If I do use math, it’ll be roughly 3rd grade level, not to insult you, but because that’s all that’s really necessary.

Relativity can’t be given “point blank”.  There are steps involved.  Its conclusions are counter intuitive and impossible to believe without being walked through the simple steps of reason to get there.  This first article will be that first step.

Let’s begin with the end though, so you’ll know what we’re building up to; the impossible to believe conclusions:  (and I give these intentionally with no explanation in this Part I)

[GARD]

• Nothing with mass can go faster than light. (I acknowledge the recent news that claims neutrinos were recently measured at slightly faster than light speed.  This is still uncomfirmed.  More later).
• If you could go faster than light, you could go backwards in time.
• The faster you travel, the slower your local time is compared to the rest of the universe.  (You’ll age slower and your clocks will tick slower).
• The faster you travel, the shorter you and your ship become.
• The faster you travel, the more massive you become.
• If you were to reach the speed of light, you would have infinite mass.
• If you were to reach the speed of light, you would be completely compressed into a 2 dimensional plane.
• It would take infinite energy for you to reach the speed of light.
• It would take infinite time for you to reach the speed of light.
• There’s no “universal time”.  Time is relative to the observer.
• There are no universal coordinates in space.  Space is relative.
• Two travelers going at different speeds disagree on length, time, and order of events because time and space are relativeAnd  BOTH observers’ measurements right even though they disagree!
• Time moves slower in gravity fields.  The stronger the gravity, the slower time moves.

All the statements above are 100% true and if you don’t believe me and you’re not privy to how relativity works, then that proves your mind is working properly and you’re ready to begin.  Your skepticism is well founded.  Here we go!

First, let’s absorb a strange fact that was observed and confirmed well over 100 years ago and confirmed over and over in experiment after experiment, so much so that much of our modern technology relies on it.

The Speed of Light is Constant.

Most people misunderstand what that means until they start learning about relativity.  That does’t just mean that light always exits its source at 186,000 miles per second.  It also means that if someone were flying away from you in a fast space ship and going say, 99% the speed of light and shown a bean of light towards you from the back of their ship, not only would they measure the speed leaving their ship at full light speed, you’d measure it passing YOU at full light speed (which we’ll call “c” from this point forward).  You would NOT measure it at c minus their ship speed like you’d measure the speed of say a bullet leaving their ship at bullet speed minus their ship speed.  Light is different.

Reread that last paragraph.  It’s fundamental.  This weirdness is not derived from complex theories and calculations.  It’s derived from direct observation.  Nobody knows why this is.  It just is.  It’s difficult to accept, but it’s true.  It’s been observed and tested time and time again.  At no point has any light ever been measured at anything other than c from any source, whether it be from galaxies billions of light years away receeding at near light speed or from double star systems where the stars are orbiting closely at high speeds, receeding, then aproaching us in their orbits, nor from anything local, like the sun or our own satelites, nor from anything on Earth.  NOTHING!  Light may be delayed though, when passing through materials like air, glass, or water, but it never goes faster than c.

This is a well known, well established, and well tested phenomenon.  Most, if not all of the weird bullet points listed above are based on this one freaky fact of nature.

Nothing is as it seems.

This is called, “The Constancy of the Speed of Light”.

Before I conclude this Part I, I’ll ask you to wait 24 hours before moving on to Part II.  Let this oddity of the constancy of the speed of light simmer in your mind for a while.  It’s a difficult concept to accept and there’s no known logical reason why c is constant.  We just know that it is… always.  Here’s your homework assignment, which you’re probably already doing:  Come up with logical reasons why this can’t possibly be true.  Why this can’t add up mathematically.  If someone in that fast moving ship shines a beam of light, out the back, to you, and you BOTH measure it as exactly c, what would that mean?  What illogical and crazy things would have to be true for c to always be constant?

These are probably the questions Einstein asked himself that triggered him to come up with the theory of relativity.

This concludes Part I.  Please wait 24 hours before reading Part II.

Relativity for Everyone:  Part II:  Time and Length are Relative

See this image?