If that title didn't bore the pants off of you, then the rest of this blog will!
The San Francisco Gate recently published an amazing article on retrocausality, which is the idea that things we do in the present go backwards in time to affect the past.
Naturally, many scientists think its silly to think you can go back in time: that would require something to go faster than the speed of light.
Plus, what about causality? Say I got my hair cut today. Then say I went back in time to yesterday to burn down my barber's place (no offense Scott, its just an illustration). Would my hair instantly grow back?
In general, this debate is between Einstein and his General Relativity fans, and the Quantum Physics fans. The former say time travel and faster-than-light travel is impossible, because that leads to incredibly weird paradoxes and a breakdown of causality.
The Quantum Physics folks basically reply, "Boo hoo! We've been dealing with incredibly weird paradoxes and a breakdown of causality for a hundred years... AND we've invented the laser, the computer, and superconductivity. What do you got?"
As you may have guessed, I side with the latter camp...
I am glad to read about a fearless quantum physics geek who may actually be able to prove time travel on a small scale is possible.
Boring physics experiments aside, the article goes into detail about the possibility that there is nothing strange at all about retrocausality. Quite possibly, time travel happens every day in small ways, and we are just not aware of it.
My hero, Richard Feynman, famously noted that a positron behaves exactly like an electron traveling backwards in time. Others have expanded on his observation with very interesting results. Perhaps these particles even go back in time all the way to the big bang, to affect the fundamental nature of our universe!
Paul Davies at the University in Sydney took this idea one step further... he and many other scientists have always been surprised at how unusually hospitable for life our universe is. If you look at how many ways it could have evolved after the big bang, its remarkable that we exist at all.
One theory is that this is nothing remarkable at all: there could have been an infinite number of big bangs before this one. If it was inhospitable to life, there would be no observer. The most recent kaboom just happened to work out well, and therefore we just happen to be around to observe it. Its just a numbers game. Fair enough...
However, if retrocausality actually happens, that means that we may live in a self tuning universe. Perhaps an unstable universe would have a lot of time traveling particles, affecting how the big bang happened, and it eventually settled down into the universe we now observe... if there is such a thing as "now".
It also leads to the possibility that disastrous time paradoxes may only exist in an unstable universe. In our universe, if somebody tried to do too much time travel, it might cause a flood of positrons to go back in time to make things more stable again... possibly by annihilating the time traveling anomaly before he does any damage.
Bad news for Dr. Who, I guess...