Since Einstein we have known that gravity was somehow special. Physicists have a unified standard model of forces and elementary particles but everyone knows that the big problem is gravity. String theory contains gravitons and explains gravity like any of the other forces. But String theory has a lot of things, in fact it is more a tool set or framework than a single theory.
But what if gravity is just a shadow on the cave wall? Or, to put it in terms a physicist would use, what if gravity is emergent—the holographic affect of entanglement entropy? I have written about it before because the idea seems to be gaining steam, at least among wannabe crackpots (like me perhaps).
Ted Jacobson (no crackpot) wrote the seminal paper in 1995 describing how to derive Eistein’s General Relativity equations from, “the form of black hole entropy together with the fundamental relation Q = TdS.” It is a short elegant paper that has been sited often of late. Back in 1995 it was pretty hard for an amateur to follow controversy in the physics world so I didn’t notice a big reaction to Jacobson.
Then came Verlinde who shook things up in January of this year. I’ve already written about the reaction.
Verlinde seems to have started a lot of people thinking because there have been several new papers jumping on the bandwagon (1,2). In a recent FQXi post Vlatko Vedral shills his own coverage of the territory in his book, Decoding Reality.
I adopted his (Jacobson’s) logic in my book to suggest, with a tongue in cheek, that gravity can in fact be derived from information theory (albeit with a little bit of help from quantum entanglement). Vlatko Vedral.
For whatever intuition is worth, the ideas of entropy (which is tied to the arrow of time) and entanglement (spooky action at a distance) do seem to be special too. Â And wasn’t it that honored cosmologist David Brin who said our universe is just a gigantic simulation?
Update: FQXi covers several of the papers and posts you’ve seen here but you might like the writing better. Check it out.