If you read my original post “What Cosmos Got Wrong Last Night,” you will know that I objected to their graphics department’s depictions of atoms. They showed electrons having flaming tails in orbits around atoms which is just wrong. I won’t repeat that objection as I had no expectation that that would have been fixed in this latest episode. Those episodes have been “in the can” for weeks I am sure. So, again in this episode atoms are depicted as being roughly spherical with a translucent outer membrane within which electrons spin in orbits around the nucleus. They look a little like fish or frog’s eggs, albeit with sparkly bits whizzing around inside. There is no membrane. There is no outer surface. There are no orbits. Enough said.
What they got wrong that was new was their depictions of atomic nuclei. I don’t blame them so much as most school books get this wrong (still!) possibly because they are just copying schoolbook diagrams in previous books. The big mistake was depicting atomic nuclei as bunches of separate particles. In one case they had roseate proton bubbles mixed in with blue neutron bubbles, both jiggling nicely. The only problem with this depiction is … wait for it … there are no protons and no neutrons in atomic nuclei. But, but, sputter, we were told…! Yes, I know, but people don’t always use their words well. You see, atomic nuclei are not made “of” protons and neutrons, they are made “from” protons and neutrons.
“… there are no protons and no neutrons in atomic nuclei. But, but, sputter, we were told…!”
Atomic nuclei are made in stars (the furnaces of creation). Ordinary stars make the elements up to iron on the periodic table and the elements past iron on that table are made when super massive stars explode as supernovae. These nuclei are made by a process called nuclear fusion in which the word “fusion” is meant to imply the elementary particles are melted together to make new ones. In our sun, right now, hydrogen is being fused together to make helium nuclei. The helium nuclei are made by fusing two protons and two neutrons together to make a new single particle. That particle, the helium nucleus, has all of the charge of the four particles it is made “from” but not quite all of the mass. Some of the mass of the four particles was converted into energy in the fusion process (which is why physicists are trying to harness this process to produce energy). And this is where Einstein’s famous equation comes in: E = mc2. The energy made when that mass is converted is equal to the amount of mass multiplied by a very large number (the speed of light) twice! That tells you that a tiny amount of mass will make a large amount of energy.
Now, it is important to note, that the helium nucleus this created is not massive enough to break apart into two protons and two neutrons. This is the only reason this nucleus is stable. People think that the “protons in that nucleus repel one another and the neutrons help them by keeping them apart.” That’s a nice description for fourth graders, but not for adults. The real reason is that there are no protons any more, they were destroyed when they were fused together with the other particles, there is but a single particle of a 2+ charge. There are no particles to separate or to repel each other.
Just to make the story complete; as helium and hydrogen are fused into heavier and heavier elements (lithium, carbon, … , up to iron) energy is given off, but in ever diminishing amounts. As the amounts of energy diminish, the gravity of the star crushes it into a smaller and smaller space. This is why stars “die.” And only in the mindboggling massively energetic explosions of supernovae are the other elements made as they can only be made with an input of energy, quite a bit of it.
The other thing Cosmos got wrong last night was a comment made by NDT about the 10 million year journey of a photon created in the center of the Sun to make is way out of the Sun to radiate off into space, and even maybe get intercept by a planet (most of the light, almost all of it, misses any planet and keeps on going). In describing this process he stated that photons bounce off of atoms ricocheting in a random fashion, so are immensely slowed. Actually in the center of the Sun, there are no atoms. There is so much energy available that the electrons are so energetic that no nucleus can hold them. I mentioned in that prior post that electrons bound to atoms have only certain energies that they can possess (why is a mystery). And electrons can only absorb photons that have energies corresponding to two of their “allowed” energy states; otherwise the photon just keeps rolling. What I didn’t tell you is that unbound electrons can absorb any amount of energy a photon has. So NDT’s newly created solar photon is not bouncing off of “atoms” but is being absorbed by electrons (and even nuclei) and then recreated a short time later with its direction of travel made random. I do not know how one could tell if the photon absorbed and the photo created are the same photon, but I’d have to guess not. (If you can’t tell them apart, then the point is moot as they all are identical, save for the amount of energy involved.) How electrons are able to do this is somewhat of a mystery. But if you magically were able to wiggle an electron fast enough you could create light that way. The reason I say the photon absorbed and the photon released later are not the same is because there are naturally occurring minerals that absorb light and release it minutes or even hours later (They can even convert ultraviolet light into visible light and look quite spooky under “black light.”) During the time the light is stored, those photons do not materially exist, their kinetic energy having been converted into potential energy.
In summation, I am finding the new Cosmos series quite delightful and “must see” TV and I hope grade schools up through colleges will play this series for every student coming through. I just wish they had been a little more accurate in some of their depictions because, as you know, “a picture is worth a thousand words.”