Lightspeed is Easy

It's not very hard to get lightspeed
Without using up any fuel.
Just follow St. Albert's equation
Transformed by the following rule:

Divide all the mass of your starship
Into all of its energy; then
Just take the square root of the quotient--
c equals root e-over-m!

CHORUS:
  c equals, c equals,
  c equals root e-over-m, over-m.
  c equals, c equals,
  c equals root e-over-m.