Quote:
Originally Posted by Grey
I'm on the other side of this, actually. That is, I agree that these are just models, and that we use them because they work. But why is it "overwhelmingly obvious" that this is not what reality is like? Perhaps the reason that it works so well is that it actually is pretty close to what "real reality" is. Maybe photons really do take all possible paths from their source to their destination, having infinitely many virtual interactions along the way, just like a Feynman diagram suggests. I'm not saying that the universe must be working that way. I'm asking why it's obvious that it can't be.
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When I get thoughts like these, I put on my 'history hat'.
That there were really, really smart people in ancient Greece, Rome, China, India, ... is where I start from. Sadly, much of what these really smart people worked out is lost to us - no written records survive.
However, from what does survive, we can get a sense of just how reasonable it seemed to those folk that 'air, water, fire, earth' was pretty close to what real reality is.
Or, to take a more recent example, phlogiston.
From ancient Greece to today is a mere ~2500 years (and ~500 from phlogiston); did the universe change so dramatically in such a short time? Or did we?
If we could fast forward 500, or 2500, years, how much like phlogiston, or earth/air/water/fire, would 'photons' and 'Feynman diagrams' seem?
An easier way to see this: between the proton and the top quark is what, ~2 OOM (in mass)? Add in the electron, and it's ~5 OOM. When the LHC comes on stream, we will get up to ~10 TeV, which will be another ~2 OOM.
Look at all the richness of the universe, in those ~6 OOM!
Yet we have detected cosmic rays with energies of ~10
20 eV ... there are more decades, in particle energy, between what the LHC will reach and these EHECRs as between the electron and top quark. What richness is there, in the universe, in these ~7 OOM?
Or take the Planck length, and compare it with the shortest distance we have been able to probe so far; then compare that with how rich the universe is, in classes of phenomena, between a thousandth of a proton's radius and (say) the solar system.