[I absolutely love being able to use that title.]
I always love when public television has a science series, at least until I've seen it; they start strong, but then end up in hand-waving and speculation and far removed from what the series promised. The most recent show, "Genius by Stephen Hawking" has the same problems, but because of the name attached to the show, people might be thinking "well, the guy's a genius, so he must be right."
Once again, the first episode of the series was excellent and the second was pretty good. Then it started to wobble just a bit. When discussing the possibility of traveling back in time, the people involved discover that it would require there being three of the time traveler simultaneously and they decide that creating matter out of nothingness makes it impossible. Hawking says, correctly, that "it's hard to imagine how this could happen on a large scale." That's technically true, but it does happen on the subatomic level. A particle moving at just under the speed of light has a finite probability (due to quantum mechanics) of going faster than the speed of light, which requires moving backward in time. This has been seen: the recorder shows what appears to be a particle moving normally, plus a copy of the particle and its anti-particle arising from it and then crashing into each other and annihilating each other. On a human scale, this would require this to happen maybe 100000000000000000000000000000 times, simultaneously, with each part shifting the same quantized amount - and then it might only last a fraction of a second.
But it is possible. And that's important for a point I'll make in a moment.
The show falters with the question of "Why are we here?" which becomes "Why are we in this location?" rather than "Why do we exist at all?" through subtle semantic shifts. He tries to cover the question of free will vs. determinism by stating that the brain, being made of matter, must act under the deterministic rules of physics (true, as far as it goes) and shows an experiment that demonstrates that the brain subconsciously makes a decision before the brain consciously is aware of it. Unfortunately, Hawking's understanding of the brain is no better than my understanding of black holes. All the experiment shows is that going from a thought to a thought about a thought takes time.
Consider going for a walk. You have to decide to put one foot forward and then decide to put the next foot forward, but unless you've suffered a brain injury (or are a toddler, in which case congratulations on reading so young), you don't consciously think about those decisions. That doesn't mean that you didn't choose to make them consciously.
Things really start to unravel when he postulates that every decision creates parallel universes. It's not a bad theory, but unprovable. He ends up saying that we are where we are deterministically because in this one chain of events, there was no other possibility. Unfortunately, this contradicts what he said earlier:
Let's go back to time travel. When one makes the decision to move back in time, the other two new "selves" that are necessary are now in parallel universes and one would not be aware of them! So time travel should be possible. In fact, with an infinite number of possible universes, it must happen, and frequently, but we are unaware of it.
There's more episodes to come. I wonder where we go next.
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