Why Einstein Gets the Last Laugh

Theoretical Physicist, Author, and Science Educator
The physicist scoffed at the idea of quantum entanglement, calling it “spooky action at a distance.” And while it has in fact been proven to exist, this entanglement can’t be used to transmit any usable information.
  • Transcript


Question: Could quantum entanglement be used to transmit information instantaneously between interplanetary spaceships? (Submitted by Matthew Del Favero)

Michio Kaku:  Matthew, the answer is yes and no.  First of all, Albert Einstein hated quantum entanglement.  He called it "spooky action at a distance."  He couldn’t get his head around it, but hey, Einstein was wrong.  We do this every day in the laboratory and here is how it works:  Let’s say we take two electrons very close together and they vibrate in unison.  Everything vibrates.  Two particles together vibrate in unison.  Now separate them.  As you separate these two coherent particles an umbilical cord, an invisible umbilical cord starts to develop between these two particles such that if you wiggle one particle then the other particle is aware of the fact that its partner is being wiggled. 

So far so good, right? But now separate these particles by the distance of a galaxy itself, so here at one end of the galaxy we wiggle an electron and on the other side of the galaxy, a hundred thousand light years distance, instantly, faster than the speed of light the other particle is aware of the fact that its twin is wiggling.  Now Einstein said: "This is ridiculous because nothing can go faster than the speed of light." But this affect has been measured.  However, you raise an interesting question.  Can you send a message this way?  And the answer is probably no.  You see, the information traveling from one electron to the other electron faster than the speed of light on the other side of the galaxy is random information.  It’s not Morse code.  You can’t send a love letter from one part of the universe to another part of the universe faster than the speed of light because a love letter has net information, so in some sense maybe Einstein has the last laugh.  It does mean that we have to revise the famous statement "Nothing can go faster than the speed of light."  Now what we have to say is "No useable information can travel faster than the speed of light." So in some sense Einstein still has the last laugh.