Interesting Throughout

Here are a few interesting factoids from Marcus Chown’s book, Infinity in the Palm of Your Hand. First up, the unknowable. We think of computers as machines that can solve any problem. But did you know that the man who broke the Enigma code, Alan Turing, being a mathematician, was more interested in knowing the ultimate limit to what a computer could do? And this, at a time, when computers were not even a reality. Mathematicians!

“Incredibly, it turns out that most problems cannot be computed by computers. It is as if there exists a small archipelago of computable problems – which mathematicians have found – lost in a vast ocean of uncomputable problems.”

Even more incredibly, this has “not held us back technologically”!

 

Helium is a liquid that can never freeze. No, not even at absolute zero. It’s got something to do with quantum uncertainty, which I won’t bore you with. Why then did I even mention it? To share his punchline:

“Hell will freeze over long before liquid helium does.”

 

Physicists love to tell you that time flows at different rates for different observers:

“There is no such thing as a common past, present and future.”

So why then do we have such a clear perception of that moment we call “now”? As always, if you can’t find the answer in physics, turn to (drum beats) evolution:

“Early in the evolution of life, there may have been organisms that experienced time in a myriad different ways, not just the way we do today. But say a tree frog had a delayed present, and focused on information from ten seconds ago – if a fly alighted on a leaf in front of it, by the time the frog lashed out its tongue, the fly would have long gone. Reliant on such out-of-date information… the tree frog would eventually have starved to death.”

 

Another thing physicists love to tell you is that when you look into space, you are looking at the past. Because light takes time to travel from whatever you are looking at to you. But this is the best analogy I’ve heard to explain that point:

“Imagine you live in central London and you look out of your window and 100 meters down horse drawn carts are clogging the street. Three hundred and fifty meters away, the Great Fire of London is turning the sky ruby-red. Two kilometers away, the first Roman ships are docking on the marshy banks of the Thames.”

Sounds ridiculous, right? Until Chown says:

“What I have described is simply what you would see from a window in Central London if light were slowed to the speed of 100 meters per century.”

 

Like I said, it’s a great book with endlessly fascinating tidbits.