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To John Wheeler, the race to explain time was personal

nautil.us

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Re: To John Wheeler, the race to explain time was personal

#41

Post by jdblair »

yodon wrote: post #3

I was lucky enough to have met John Wheeler when I was in grad school. He was a wonderful man who radiated joy and curiosity. My favorite anecdote about him, which was not widely known, involved what used to be called "nut letters." Before the internet, if you were a famous scientist, particularly a famous physicist, you would receive actual letters from people all over the world asking for help with their perpetual…

At the fantastic Museum of Jurassic Technology, in Los Angeles, there is a wonderful display of actual letters like this sent to the Mount Wilson Observatory. They are beautiful for their earnest curiosity. Some of these letters are online here: http://www.mjt.org/exhibits/letters/letters.html

Re: To John Wheeler, the race to explain time was personal

#42

Post by goblin89 »

kieckerjan wrote: post #36

What irks me in articles like this is the term observer. Define observer. Sure, a human is an observer. But can a dog be an observer? A plasmodium? A virus bumping into a molecule and changing its course? Is observing shorthand for any interaction that can collapse a wave function? In that case it seems highly unlikely to me that a photon can travel billions of light years unperturbed.

> The relevant literature is famously contentious and obscure. I believe it will remain so until someone constructs, within the formalism of quantum mechanics, an “observer,” that is, a model entity whose states correspond to a recognizable caricature of conscious awareness … That is a formidable project, extending well-beyond what is conventionally considered physics

Wilczek, 2006. Quoted in a paper[0] that I like for its thorough stab at actually specifically defining the observer. It’s a tough task indeed!

[0] https://www.frontiersin.org/articles/10.3389/fpsyg.2014.0057...

Re: To John Wheeler, the race to explain time was personal

#43

Post by selestify »

commentor10 wrote: post #12
empath75 wrote: post #2

On observers creating the universe, I’ve sometimes wondered if given the simulation hypothesis, that simulating quantum mechanics is so computationally expensive that it isn’t done unless we’re looking at it, and that the high energy levels required to probe smaller and smaller length scales is an artifact of the computational requirements of simulating it.

I find it funny how people are so ready to believe the universe must be computing the same way our models must. The universe simply exists - it's not necessary for it to adhere to our human perceptions - not be a long shot. There's a vast gulf between the model and the modeled. That our theories quickly become uncomputable says more about their unfitness than the universe's functioning. To say otherwise is to negate…

What autonomy does the universe possess?

Re: To John Wheeler, the race to explain time was personal

#44

Post by kgwgk »

ars wrote: post #33
zinclozenge wrote: post #22

Earlier quoted context omitted.

You are getting relativity wrong. The layman phrase being used here 'time come to a halt and disappear' encodes what would happen from a relativity perspective. Everything that you would be seeing relative to you, would appear as if time had stopped if you were traveling at c.

If you were traveling at C you would not really see anything [external] at all. Length contraction would be such that everything around you would appear as a single motionless point. Any incoming light would be blue shifted to infinity, or red shifted to zero, so if any actually touched you there would be infinite energy there. Luckily no light can actually reach you - nothing can. You would have no incoming sensory…

If you were traveling at c you would be a photon :-)

Re: To John Wheeler, the race to explain time was personal

#45

Post by contravariant »

kieckerjan wrote: post #36

What irks me in articles like this is the term observer. Define observer. Sure, a human is an observer. But can a dog be an observer? A plasmodium? A virus bumping into a molecule and changing its course? Is observing shorthand for any interaction that can collapse a wave function? In that case it seems highly unlikely to me that a photon can travel billions of light years unperturbed.

I prefer the quantum decoherence perspective where being 'observed' basically means interacting with a macroscopic object in a way that's similar to the notion of reaching 'thermodynamic equilibrium' in statistical physics.

Re: To John Wheeler, the race to explain time was personal

#46

Post by commentor10 »

kieckerjan wrote: post #36

What irks me in articles like this is the term observer. Define observer. Sure, a human is an observer. But can a dog be an observer? A plasmodium? A virus bumping into a molecule and changing its course? Is observing shorthand for any interaction that can collapse a wave function? In that case it seems highly unlikely to me that a photon can travel billions of light years unperturbed.

I think an observer is a quantum process interacting with another quantum process. Photons are fundamentally different from particles with mass - and they interact differently. Two photons interact like waves at the surface of an ocean - amplitudes and phases changing, for instance. But photons interact with particles with mass by either being absorbed and, later, re-emitted by the other particle or being completely absorbed and altering the particle with mass' state in some way (speed/momentum).

I remember reading somewhere about a geometry which described photons' existences as fundamentally different from particles with mass. Particles with mass have lifelines that change over the course of time. Particles without mass, such as photons, don't experience time and never change themselves. Photons etch out a straight line in this geometry from fixed points to other fixed points. The fixed points represent particles with mass. (something like that)

Re: To John Wheeler, the race to explain time was personal

#47

Post by gregdunn »

omazurov wrote: post #20

> The faster you go, the slower time goes. If you could go as fast as light, you’d see time come to a halt and disappear. No, you wouldn't. Someone observing you would. Am I getting relativity wrong?

Yep. Time still passes for photons, but, at a rate so insanely slow in comparison to how we view it.

10^18 years by our perspective would only be 3 years by the perspective of something traveling at the speed of light.

We observe things going the speed of light all the time =]

Re: To John Wheeler, the race to explain time was personal

#48

Post by commentor10 »

selestify wrote: post #43
commentor10 wrote: post #12

Earlier quoted context omitted.

I find it funny how people are so ready to believe the universe must be computing the same way our models must. The universe simply exists - it's not necessary for it to adhere to our human perceptions - not be a long shot. There's a vast gulf between the model and the modeled. That our theories quickly become uncomputable says more about their unfitness than the universe's functioning. To say otherwise is to negate…

What autonomy does the universe possess?

For one, it exists before any of our feeble explanations of how it works. It's always correct and we try to play catch up.

Re: To John Wheeler, the race to explain time was personal

#49

Post by aidenn0 »

contravariant wrote: post #45
kieckerjan wrote: post #36

What irks me in articles like this is the term observer. Define observer. Sure, a human is an observer. But can a dog be an observer? A plasmodium? A virus bumping into a molecule and changing its course? Is observing shorthand for any interaction that can collapse a wave function? In that case it seems highly unlikely to me that a photon can travel billions of light years unperturbed.

I prefer the quantum decoherence perspective where being 'observed' basically means interacting with a macroscopic object in a way that's similar to the notion of reaching 'thermodynamic equilibrium' in statistical physics.

"macroscopic object" is unsatisfying though because macroscopic objects are made out of objects that are describable under QM.

Re: To John Wheeler, the race to explain time was personal

#50

Post by vorg »

gloriousduke wrote: post #31

I need to get caught up on new developments regarding Wheeler's "Participatory Universe" to find out if anyone else is thinking along these lines, but if observation does result in existence becoming--wave function(s) collapsing into the truly concrete--then essentially the history of the Universe occurred instantly when the first observation of it was made? I don't know where that conscious observer would have been…

> the history of the Universe occurred instantly when the first observation of it was made

Perhaps that history could still collapse into existence in stages, as subsequent observations of it became more detailed. The first observer would see far-off galaxies as small white dots in the sky, but not the composition and interaction of each, so perhaps those aspects don't decohere until later observers see more using telescopes.

And not only history but also laws of physics could come into existence in this way. If earthlings are the only observers in the Universe, perhaps dark matter holding galaxies in a circular shape is a law of physics which only came into existence when observers on Earth could start seeing inside other galaxies.

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