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First Experimental Evidence That Time Is an Emergent Quantum Phenomenon
KentuckyFC writes "One of the great challenges in physics is to unite the theories of quantum mechanics and general relativity. But all attempts to do this all run into the famous 'problem of time' — the resulting equations describe a static universe in which nothing ever happens. In 1983, theoreticians showed how this could be solved if time is an emergent phenomenon based on entanglement, the phenomenon in which two quantum particles share the same existence. An external, god-like observer always sees no difference between these particles compared to an external objective clock. But an observer who measures one of the pair — and so becomes entangled with it--can immediately see how it evolves differently from its partner. So from the outside the universe appears static and unchanging, while objects that are entangled within it experience the maelstrom of change. Now quantum physicists have performed the first experimental test of this idea by measuring the evolution of a pair of entangled photons in two different ways. An external god-like observer sees no difference while an observer who measures one particle and becomes entangled with it does see the change. In other words, the experiment shows how time is an emergent phenomenon based on entanglement, in which case the contradiction between quantum mechanics and general relativity seems to melt away."
It's because the subject takes time to digest and respond to intelligently. As opposed to the usual "NSA is Monitoring My Brain" headline. It's nice to see this type of article, it's what brought me to slashdot so many years ago. I still come everyday hoping to see more stuff like this.
After reading a lot on this is that sometimes an issue becomes a problem without reason.
Now, time is ONLY a man made measure - a measure between events. Nature/the universe doesn't know what time is nor cares about it. It is only us humans that need to try to explain time dilation and various other 'time issues' to make the maths work. Remove time, and I bet it will balance these equations.
Time cannot run backwards,as there is no such thing as time except in the human brain and the human concept of measuring changes.
Nature doesn't care about time? Tell that to the laws of thermodynamics. Entropy only goes one way.
If you watch a video of a ball rolling on a desk, you can't tell just by the video whether time has been reversed. The physics governing that motion don't care about time. If you watch a video of an egg being shattered, you'll know when the video is reversed. You know all the contents of the egg can't spontaneously get back together as time moves forward. That would be going to a much more well-ordered state.
Also, the GPS device you use to triangulate your position and navigate to your destination? Well, consider that relativity tells us that the satellites zooming up above us have slower ticking clocks. They're actually moving through time slower than you are, and our current GPS accuracy wouldn't be achievable if we didn't take that into account.
Just keep in mind that an 'observer' does not mean a conscious entity. An observer, in the quantum mechanical sense, is more accurately an "interactor", as in anything that interacts with it. Which, when put into those terms, their thought process in this paper is much clearer: without interaction there is no way to determine if time has passed, if there's no way to tell if time is passing... it may as well not be.
There are other physical constants, too. The charge of the electron for one and Plank's constant for another. The reality of a 'physical constant' is that it is just a ratio of one measured quantity in the observed Universe to another measured quantity that is always the same, so is sort of a conversion factor between physical observables which are somehow tightly related (not a great explanation, I know).
As for your light from the flashlight story -- there is no easy explanation because the easy explanations all depend on things behaving as we have grown up observing and internally modeling them in our low energy, slow speed existence. The explanation is just that at high relative speeds between observers the measurements of time and distance mix into each other such that each observer will always observe a light beam (in a vacuum) to be at 1.0c no matter what the speed of its source. A slightly deeper explanation is that time and 3 dimensional space form a four dimensional manifold (fancy name for something which local coordinates can be mapped to a flat space) in which the mix of time and space dimensions depends on the motion of the observer (actually reference frame of the observer). Relativistic effects are beyond the classical existence we model in heads growing up and so require math to take us beyond intuitive notions, that's about all I've got on the issue.
You (as are most people with a poor grasp of these physics because of some shitty analogy someone used to explain it to them) are making the common mistake that the person with the flashlight in hand would think the light is traveling at 1c away from him (total of 1.5c) but they wouldn't see any such thing.
Yes they would see it traveling away at 1c - but the velocities don't sum like that. Due to time dilation, you're also experiencing time at a different rate than a stationary observer. The net effect is that you both see the light traveling at 1c.
To extend the analogy, suppose both people also have a stopwatch which starts timing at the exact moment when the person who's moving at 0.5c fires a pulse of light in the same direction as his movement. After the observer's stopwatch has reached 1 second, freeze everything and see where everyone is. The person who's moving at 0.5c has moved half the distance light travels in 1 second, obviously; about 149 896 km. The pulse of light has moved twice as far, about 299 792 km.
To the outside observer, the light has traveled 299 792 km in 1 second, i.e. it is moving at 1c.
The moving person, saw it travel only half as far relative to him - only 149 896 km - yet, because he's experiencing time at a different rate, his stopwatch has only ticked off 0.5 seconds. So from his perspective, the light has traveled 149 896 km in only 0.5 seconds, i.e. it is moving at 1c.