Thursday, February 07, 2013

In which I take on a Quantum Physics problem

Let me start by acknowledging that real science is hard. People way smarter than me with advanced degrees and a lifetime of experience toil away at the smallest issues to advance knowledge bit by bit. Amateurs have no part to play - anyone without at least a PhD who claims to have a "Eureka" moment is either deluded or trying to sell something to the gullible.

That said, I've had a "Eureka" moment. Unfortunately I'm not trying to sell anything to the gullible. I wish I were because, frankly, I could do with the money.

Quantum Physics is weird. Lots of stuff happens that doesn't make sense, but it can be demonstrated to be real. However there is one phenomenon which seems weird that I think can be easily explained. Without spending the next thousand words describing it, there are experiments using light which seem to require the light to send information back in time (to itself) do determine how it will later behave. For some background reading check out Wheeler's delayed choice experiment and Delayed choice quantum eraser (in particular the Problems with using retrocausality section).

So to cut a long story short, different results can be obtained, at the time of the experiment, which vary in a way which is only possible if the light changes the way it behaves before the experiment is conducted. It seems that the light reaches the experimentation site and sends a message to itself in the past dictating how it should behave.

Anyone who has studied enough Physics eventually comes to accept that time isn't absolute. The faster you go, the less time passes for you compared with slower dudes (see the Twin Paradox). The closer you get to the speed of light, the slower time goes. Of course it goes the same speed for you, but your Earth bound colleagues will age much more quickly than you. Nothing can travel "at" the speed of light except, well, light (actually that's not strictly true, but to travel at the speed of light requires zero mass - neutrinos may qualify).

The thing is, if you do happen to travel at the speed of light, there is no time. A photon of light is created, travels and is extinguished (converted to another form of energy) in zero time in the photon's frame of reference. Not "really quickly", exactly zero time. Now here's where it gets odd, because from where we stand we see light travelling quickly, but still taking time. Eight or so minutes to get from the Sun to here, four and some years to get from the next nearest star to here. Yet each photon experiences zero time for its journey, no matter how long it takes in our frame of reference.

Here's the Eureka stuff.

At any given instant my body is approximately 183 cm (6 feet) long. I have no problem detecting my feet and my head at the same time. To a photon its entire journey, be it from a torch or a distant star, occurs at the same instant. It happens in varying physical lengths, but zero time. For the photon to send a message from the end of its "life" to nearer the beginning of its life does not require sending a message back in time, because its whole life happens at exactly one instant in time. It requires sending a message from one physical point to another, both of which are experiencing the same time. The end and the beginning are at the same time. We see the photon taking time to reach its destination, but that's only from our frame of reference.

From the point of view of the photon, in Wheeler's experiment, the detector screen isn't being removed "after" the light has passed the double-slits because the whole journey is happening at the same time. The photon at the physical end point of its journey communicates with itself at an earlier physical point (since it is at the same time from its point of view) and behaves accordingly.

Therefore no time travel is required and there is no paradox. It's just one physical location of the photon communicating with another physical location of the photon, both of which exist simultaneously.



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