Feynman's empty space isn't really empty space

[pentazoid]

At a physics conference on the east coast, feynman says that empty space isn't really empty but empty space make up of tiny elementary particles that have yet to be detected, and he demonstrated that space is not empty using his feynman diagrams. Physicists at the conference rejected feynman's ideas and conclusion about "empty space". some even calling his ideas crackpot ideas. I don't understand how physicists at the conference could not visualize subatomic matter making up empty space. I can't visualized an entity like empty matter being composed of nothing. I can't pictured seeing "nothing" when observing empty space. That notion seems counterintuitive to me. How can there be elementary particles and then how can their be empty space made of nothing. Your thoughtS?

 

[jtbell]

At a physics conference on the east coast, feynman says

Which conference was this? Richard P. Feynman has been dead for over twenty years.

Physicists at the conference rejected feynman's ideas and conclusion about "empty space". some even calling his ideas crackpot ideas.

Reference, please.

 

[pentazoid]

Which conference was this? Richard P. Feynman has been dead for over twenty years.

I wasn't talking about any recent physics conferences. I was actually talking about the physics conference held in the late 40's at the coast of pennsylvania were all the celebrities of physics gathered, like oppenheimer , bohr's and dirac

Reference, please.

I found about about this conference through a video documentary on QED on youtube.

http://www.youtube.com/watch?v=i8O_yQHxQos&feature=PlayList&p=8214558E2B082D20&index=1

Feynman's presentation on QED comes up at 2:48

 

[jtbell]

Oh, in the 1940s... that's practically ancient history! You have to remember that period was the beginning of modern quantum electrodynamics. As I recall from reading about it years ago, Julian Schwinger had developed a first version of QED that worked (he could calculate results that agreed with experiments) but it was very complicated and hard to understand. Then Feynman came along with his diagrams (which are basically mnemonic devices for setting up calculations), and got toe same results with a lot less effort. Schwinger had developed his theory rigorously and Feynman had not, so a lot of people were understandably skeptical of Feynman's methods. That skepticism pretty much went away in 1949 when Freeman Dyson showed that the two methods were actually equivalent, i.e. you can derive one from the other.

(Incidentally, Dyson is still around, at the age of 85. I recently saw him in interview segments in a TV documentary about John Adams's opera "Doctor Atomic", about Oppenheimer and the Los Alamos project.)

 

[Vanadium 50]

This sounds like an exaggeration to me. People were doing serious calculations of vacuum effects in 1947 and 1948 - the Lamb shift and electron anomalous magnetic moment. Feynman's path integral approach to QED wasn't published until 1950 (although a NRQM version was published in 1948).

Oh, and just to be pedantic - I don't believe Pennsylvania has a coast. Just a lakeshore.

 

[daschaich]

I remember reading this story in Crease and Mann's The Second Creation, which is probably a better source than YouTube (and probably where the YouTube guy got it from in the first place).

This was at the 1947 http://en.wikipedia.org/wiki/Shelter_Island_Conference" (on the coast of New York), and Crease and Mann claim (page 138 of the 1996 edition) that Feynman gave a sloppy presentation and ended up resorting to diagrams to try to clear up some of the confusion he had caused. However, he neglected to explain (and didn't get much of a chance to do so) that the diagrams were not meant to be taken literally, but were just abstract bookkeeping devices with rigorous mathematical meaning. The audience (Crease and Mann single out Bohr) thought that Feynman was trying to draw a picture of exactly what was going on, which would indeed have been a crackpot idea, so they jumped on him with both feet and effectively booed him off the stage.

So it was basically just a breakdown of communication, relatively quickly corrected, and perhaps a mildly amusing story (if only because it involves Feynman). It's not the sort of thing that should be used to draw any conclusions about what was or was not widely understood at the time. (Crease and Mann do a bit of that themselves, though the YouTube guy seems worse.)

 

[HallsofIvy]

New York doesn't have much of an "east coast". Is Shelter Island in Lake Erie?

 

[Norman]

New York doesn't have much of an "east coast". Is Shelter Island in Lake Erie?

Nope, it is actually off the Northeast tip of Long Island.

 

[jtbell]

It's nestled between the North Fork and the South Fork at the far eastern end of Long Island.

 

[Haelfix]

Incidentally one of the only people at that Shelter island conference who actually payed Feynman any heed. None other than Einstein. The other quantum physicists were still trying to digest Schwingers mathematics.

 

[Sideways]

If you want a 5-minute primer on the subject, read

http://en.wikipedia.org/wiki/Vacuum_polarization

 

[Naty1]

How can there be elementary particles and then how can their be empty space made of nothing.

If the big bang can be considered the "ultimate free lunch" where our entire universe materialized from nothing, seems like "empty" space is not so empty! Instead of "empty" space I see space curving as gravity, vacuum fluctuations producing particle/antiparticle pairs, dark energy powering the expansion of the universe, maybe dark matter, and even a minimum size: Planck area and Planck volume structured as Penrose spin networks with edges and nodes multiples of plank integers.

Others here see space as simply a mathematical construct.

 

[math_04]

I watched a youtube video of Steven Weinberg and Richard Dawkins discussing atheism and the universe. In that particular video, Weinberg talked about dark energy that was basically there even if space was 'empty'. It would seem that we lack some sort of fundamental understanding about what 'space' really is and that it may be more that just a place where things occur. I may have misunderstood him but it does seem odd that empty space would contain some energy. Oh and btw, is there any conclusive proof for dark energy? Sure, the universe is undergoing a state of accelerated expansion but is there any proof that dark energy is behind it.