quarta-feira, maio 16, 2018

Shut the Fuck Up and Calculate (Or Not): "The Nature of Space and Time" by Stephen Hawking and Roger Penrose




"I have emphasized what I consider the two most remarkable features that I have learned in my research on space and time: (1) that gravity curls up space-time so that it has a beginning and an end; (2) that there is a deep connection between gravity and thermodynamics that arises because gravity itself determines the topology of the manifold on which it acts".

In “The Nature of Space and Time" by Stephen Hawking and Roger Penrose by Stephen Hawking in the lecture "Quantum Cosmology"


"We should think of twistor space as the space in terms of which we should describe physics."

In “The Nature of Space and Time" by Stephen Hawking and Roger Penrose by Roger Penrose in the lecture "The Twistor View of Spacetime"


"These lectures have shown very clearly the difference between Roger and me. He's a Platonist and a positivist. He's worried that Schrödinger's cat is in a quantum state, where it is held alive and held dead. He feels that can't correspond to reality. But that doesn't bother me. I don't demand that a theory correspond to reality because I don't know what it is. Reality is not a quality you can test with litmus pap. All I'm concerned with is that the theory should predict the results of measurements. Quantum theory does this very successfully. It predicts that the result of an observation is either that the cat is alive or that it is dead. It is like you can't be slightly pregnant: you either are or you aren't."

In “The Nature of Space and Time" by Stephen Hawking and Roger Penrose by Stephen Hawking in the lecture "The Debate"


Can I write a review on such a book? Hawking and Penrose... It's staggering...I don't even know what day the mailman comes...After having re-read this oldie after Hawking's passing, I'd say it depends on where you are in the universe, whether you're on/near some sizeable object (of mass), its rotation, distance from other masses, or whether you live in my neck of the woods...When in doubt I always follow "the flat earth" rule (Medieval behaviour is so "in" now). The world is the centre of (my own)) universe that you/I live in and it's getting flatter every day. Which hopefully means you can see further and observe when others perform the same behaviour. Or ask them. Preferably in a suit of armour while riding a horse. Possibly a lance too. (Until you understand the society you live in). I'm all for a flat and cubist planet! Our time is here! And it'd be easier to fence. And we could launch spaceships off the corners. Uncannily, the mailman knows when I'm on the phone, asleep or having a quiet moment on the throne...I sniff a time conspiracy here (*It'll End in Tears theme music*)

When it comes to Quantum Theory, the math in the book includes every possible outcome, and the predictions it makes are simply probabilities - e.g. there's a 1% chance X will happen, 90% chance Y will happen and 9% chance Z will happen. How you choose to interpret this is still up for grabs, if you go with Everett's "Many Worlds Interpretation" idea then all possibilities are equally real and actually happen in different universes; if you go with the Copenhagen Interpretation then the wave-function of "possibilities" collapses down to one single result. On a fundamental level, whichever way you choose to interpret it (there's about 8 main contenders for interpretation) the math remains unchanged, and the possibility remains that the math itself is the "truth" and there is no further interpretation, usually called the "shut the fuck up and calculate" interpretation (my favourite).

Bottom-line: This is not a book à la Smolin, i.e., it's not for laymen. I still remember some of the reviews I read in 2010 when the second edition of the book came out. Hilarious! E.g., "Clearly the work of two great minds" (possible Translation - "I didn’t understand the bits I speed read, but they looked dead clever and I have to say summat"...).

2 comentários:

Luís Filipe Franco disse...

Didn't know this oldie.
To be read with both eyes open... not wide shut as someone has said;).

Manuel Antão disse...

Indeed Luis. Having re-read this in 2018 made me fully appreciate what both these guys did eons ago...