Posts Tagged ‘GTR’

Time for Cause & Effect?

December 31, 2014

Cause, effect, and time are all mysteries at this point. As far as Physics is concerned.

When I was a young chicken, learning physics, pecking around the way chicken do, I came upon “the Arrow of Time”. At the time, the question about the nature of time was all about “Entropy” and the “Second Law of Thermodynamics”. How quaint it seems now that I got much wiser!

Entropy is about “states”. The “Second Law” says that processes augment the number of states, as time goes by.

The most basic question is then: ”What is a state?”

People in thermodynamics thought they had an answer. And, in a way, they do, like a car mechanics is full of answers about the state of your car.

Mechanics Getting Weirder: Are There Wormholes?

Mechanics Getting Weirder: Are There Wormholes?

[Yes, these distorted things are distant galaxies, viewed through the wormhole. The picture, from the excellent movie “Interstellar” depicts how a wormhole in spacetime would appear at close range; the little flower is the rotating spaceship. Interstellar represents an Earth where society has pursued its way down the abyss, thanks to the anti-science, anti-rationality movement in evidence nowadays. NASA went underground… Something not far removed from its present state, where tantalizing clues for life on Mars are left unexamined, because of the anti-nuclear movement… Long story, another time.]

However, nature is a Quantum car. And mechanics have nothing to say about it. Quantum Physics has its own notion of state. Moreover, in the meantime, the very notion of time and causality came under attack. From an unexpected corner.

It was simple enough when Lorentz and Poincaré introduced the notion of “local time”. Time was relative (Poincaré Relativity Principle, 1904): it depended upon one’s state of motion. In a local frame moving fast, time slows down (relative to the friend who did not get on that speedy rocket).

Einstein then observed that if a local time was accelerated, it would also slow down. Einstein somehow hoped to extract from this “General Theory of Relativity” a cause for inertia, but he failed (and could only fail, as GTR is local, not global). He ended up with just a Theory of Gravitation (Fock), a better and much improved version of the one of 1700, true… But still GTR is articulated basically the same equation arising from Ismael Bullialdus considerations in 1645 (and then Huygens, Borelli, Hooke, etc.)

Enter Quantum Physics. There time is absolute (oops). Locally absolute over an extent. Why? Because each Quantum processes are logically and mathematically analyzed in a particular space, relative to said process, and GLOBALLY therein (here is that global concept Einstein was desperately searching for, as he craved for inertia as a global phenomenon, following Newton and Mach).

That particular space relative to that particular process is not just two dimensional (as in the famed double slit experiment), it can be pretty much anything that can be depicted as a Hilbert space (consider Dirac Spinor space).

In the past, before 1904, one could consider that if something A preceded something else B, in time, A could have “caused” B. However local time already messes up with that situation (consider closed time loops in GTR; reference: just released movie Interstellar, a respected relativist, Thorne, made discoveries while consulting for the movie).

Quantum Physics makes causation a worse consideration than ever. As it stands, the Quantum is Non-Local. No need to get into Spin and Bell, to figure that one out: the analysis in Quantum Hilbert space uses time only as a one parameter transformation group, it’s intrinsically Non-Local (hence the famed “Collapse of the Wave Packet).

If a physicist changes a spin axis on Earth, does it do something to the second member of the entangled photon pair he sent to Beta Centauri? Instantaneously? Really? No one knows for sure (and I don’t believe the “instantaneous” part), but the present Quantum formalism (sort of) says it does.

Paradoxically, all of this debate about cause and effect has become very practical, in the most fundamental domain possible, Quantum Physics. As real physics moves away from the multiverse derangement syndrome, it ponders using, as nature and biology, and even evolution do, the Quantum.

Indeed, even biology uses the Quantum to compute, and find best solutions (as was demonstrated in the case of the chlorophyll molecule; much more examples are on the way, including that will demonstrate how a type of Lamarckian evolution works).

However “what causes what” has stood in the way of making Quantum Computers. Real physicists and engineers have been trying to get a handle on causation. One wants to isolate the process of computation, yet get it impacted by complicated inputs, and only these.

Time to spend some money on all this (that means re-direct the economy that way).

Patrice Ayme’