TIME'S ARROW

Matter and energy are interchangeable.  Einstien showed us this in the 1900's, and many people are familiar with his E=mc2 equation.  For the rest of this page, I will refer to matter and energy as "matter/energy".

People imagine being able to travel through time by using technological contraptions, but there is a matter/energy obstacle to overcome.

time flowsto the right (in this drawing)

The amount of matter/enrgy in the universe is constant.  This idea is expressed by the law of conservation off mass/energy.  If you could travel to another time, you'd be removing some matter/energy from the current time and puting it into the future, like this

You can see that if you could do this, you could eventually destroy a chunk of the arrow.  That would mean the past didn't exist!  How could the past not exist if you lived through it?