Neil deGrasse Tyson AMA
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Neil deGrasse Tyson AMA
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Re: Neil deGrasse Tyson AMA
#2Really interesting. A couple of physics things I did not know that Neil mentions:
1) The fact that an electron has no known size -- it's smaller than the smallest measurement we have ever made of anything.
2) That Quarks come only in pairs: If you try to separate two of them, the energy you sink into the system to accomplish this feat is exactly the energy to spontaneously create two more quarks - one to partner with each of those you pulled apart.
Re: Neil deGrasse Tyson AMA
#3Really interesting. A couple of physics things I did not know that Neil mentions: 1) The fact that an electron has no known size -- it's smaller than the smallest measurement we have ever made of anything. 2) That Quarks come only in pairs: If you try to separate two of them, the energy you sink into the system to accomplish this feat is exactly the energy to spontaneously create two more quarks - one to partner with…
Huh, I thought Quarks only existed as triplets.
Re: Neil deGrasse Tyson AMA
#4Really interesting. A couple of physics things I did not know that Neil mentions: 1) The fact that an electron has no known size -- it's smaller than the smallest measurement we have ever made of anything. 2) That Quarks come only in pairs: If you try to separate two of them, the energy you sink into the system to accomplish this feat is exactly the energy to spontaneously create two more quarks - one to partner with…
re electron: It's probably more accurate to say "size" has no meaning at that scale. Particles turn into waves, spacetime isn't smooth, etc.
Re: Neil deGrasse Tyson AMA
#5Really interesting. A couple of physics things I did not know that Neil mentions: 1) The fact that an electron has no known size -- it's smaller than the smallest measurement we have ever made of anything. 2) That Quarks come only in pairs: If you try to separate two of them, the energy you sink into the system to accomplish this feat is exactly the energy to spontaneously create two more quarks - one to partner with…
Huh, I thought Quarks only existed as triplets.
They only come in "colorless" sets. The "colors" (which are just suggestive names and have nothing to do with light colors) are Red, Green, and Blue, along with anti-Red, anti-Green, and anti-Blue. Therefore, there are basically two options: mesons, which contain a quark/anti-quark pair (e.g. one Green and one anti-Green) and baryons, which contain quark of each colors (RGB, or antiRGB). Tetraquarks, pentaquarks, and hexaquarks have been searched for in experiment and would not violate the colorless rule, but have never been found. Physicists would prefer to be able to calculate from first principles whether such states are possible, but it turns out that no one knows how to do the calculation because of the non-perturbative nature of the strong force.
[Many caveats. For instance, any given hadron (the collective name for things made of quarks, which to date means only mesons and baryons) is not actually made up of quarks with definite color, but rather a quantum superposition of many possibilities. I think mesons, for example, are always a balanced superposition of R-antiR, G-antiG, and B-antiB. So you could never point to a given meson in an experiment and say "that meson was blue-antiblue".]
Re: Neil deGrasse Tyson AMA
#6Really interesting. A couple of physics things I did not know that Neil mentions: 1) The fact that an electron has no known size -- it's smaller than the smallest measurement we have ever made of anything. 2) That Quarks come only in pairs: If you try to separate two of them, the energy you sink into the system to accomplish this feat is exactly the energy to spontaneously create two more quarks - one to partner with…
Huh, I thought Quarks only existed as triplets.
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Re: Neil deGrasse Tyson AMA
#7Really interesting. A couple of physics things I did not know that Neil mentions: 1) The fact that an electron has no known size -- it's smaller than the smallest measurement we have ever made of anything. 2) That Quarks come only in pairs: If you try to separate two of them, the energy you sink into the system to accomplish this feat is exactly the energy to spontaneously create two more quarks - one to partner with…
re electron: It's probably more accurate to say "size" has no meaning at that scale. Particles turn into waves, spacetime isn't smooth, etc.
>It's probably more accurate to say "size" has no meaning at that scale
Not at all. Size has unambiguous meaning down to the Planck scale (10^-35 meters) and electrons simply haven't been probed at scales smaller than 10^-22 meters. They could very well have heretofore-undetected structure (e.g. preon models) on the scales of 10^-20 while still have fifteen orders of magnitude (about the relative span between an atom and the radius of the earth) over which distances are perfectly sensible.
Likewise, before the deep inelastic scattering experiments of the 60's, physicist had no direct evidence that neutrons and protons had any internal structure. All they could say is "we know that if they have internal structure, it's smaller than this length scale".
[FYI: The Planck scale is (arguably!) where the notion of size becomes murky because quantum fluctuations in the background spacetime (against which the sizes of things are measured) become substantial. Of course, no one has ever seen (even indirect) evidence of a quantum fluctuation in spacetime. And, as is well known, appling quantum mechanics to gravity and spacetime is full of difficulties. But most physicists believe there are such quantum effects because it seems damn near impossible to reconcile a classical spacetime with quantum everything else.]
Re: Neil deGrasse Tyson AMA
#8Really interesting. A couple of physics things I did not know that Neil mentions: 1) The fact that an electron has no known size -- it's smaller than the smallest measurement we have ever made of anything. 2) That Quarks come only in pairs: If you try to separate two of them, the energy you sink into the system to accomplish this feat is exactly the energy to spontaneously create two more quarks - one to partner with…
See also:
Q: Since time slows relative to the speed of light, does this mean that photons are essentially not moving through time at all?
A: yes. Precisely. Which means ----- are you seated? Photons have no ticking time at all, which means, as far as they are concerned, they are absorbed the instant they are emitted, even if the distance traveled is across the universe itself.
Re: Neil deGrasse Tyson AMA
#9So, so many excellent quotes in that discussion. My favorite:
"Kids are never the problem. They are born scientists. The problem is always the adults. The beat the curiosity out of the kids. They out-number kids. They vote. They wield resources. That's why my public focus is primarily adults."
Preach it, dude.
Re: Neil deGrasse Tyson AMA
#10So he's skeptical of the singularity but he thinks we'll be able to live forever in a lifetime or so. Weird.