Ever heard of the planet Vulcan? In the late 1800s, many scientists thought it was real: a hot planet near Mercury, whose gravitational pull supposedly caused a wobble in Mercury’s orbit.
Albert Einstein killed off this notion, as MIT’s Thomas Levenson recounts in his new book, “The Hunt for Vulcan,” published today by Random House.
As Einstein’s calculations showed, Mercury’s orbit fit perfectly with his theory of general relativity, in which gravity merely follows the shape of spacetime – ending any apparent need to believe in Vulcan.
Q. For how long did people believe in Vulcan, and why?
The French astronomer Urban Jean Joseph Le Verrier calculated and said those problems can be explained if there were another planet we haven’t found yet beyond the orbit of Uranus, whose gravitational tug is pulling on Uranus to create these anomalies.
So as long as Newtonian gravitation was the way to understand the universe, it was hard to understand what the absence of Vulcan meant.
It wasn’t until Einstein came along with a theoretical construct that was in conflict with Newtonian gravitation that it became [clear]: The problem wasn’t the missing planet, the problem was thinking about space and time in the wrong way.