![]() So to find healthy skepticism, we must turn to leading physicists who are not cosmologists. "By the same argument as the preceding it can be shown that the earth can neither move in any one of the aforesaid oblique directions, nor ever change at all from its place at the centre." Claudius Ptolemy. Such certainty as is found in current cosmology has precedent. But skepticism seems to have disappeared from the consensus world of cosmologists. "IF" this hypothesis is true, "IF" such and such concept or interpretation is correct. The thing that I miss most in Ethan's The Greatest Story Ever Told is the word "IF". Hence neutrinos make up at most about 5 to 6% of all dark matter. Compare that to the density parameter of dark matter in total, which is about 0.11 (same paper, table 1 on page 3). Dividing by the 94 eV, one immediately sees that the neutrino density parameter times h^2 is at most about 0.006. Then, in section 4.7, they give an upper limit on the sum of all neutrinos masses of 0.58 eV (they also provide other upper limits, using additional data, but this is enough to show the point). They give the following relation between the density parameter for neutrinos and the neutrino masses (between equations 27 and 28): the sum of all neutrino masses, divided by 94 eV, is equal to the density parameter times h^2. If you've got something within the last year or so that dismisses this possibility, I'd like to see it. So come back for part 7, where we'll see if we can't save these unstable neutrons from Your "here" link merely links back to this comment thread.?!? At this point, the Universe is still only one second old, and still hotter than the center of the Sun, but it looks an awful lot more like what you're used to! And when two down quarks and one up quark get together, they can form a stable neutron.Īll told, the matter and antimatter has all annihilated away, and so our Universe is full of the radiation left over from that, and that tiny little excess of matter: protons, neutrons, and electrons. This means when two up quarks and one down quark get together, they can finally, when the Universe is about 10 microseconds old, form a stable proton. Things are instead coming together a little more calmly. So instead of a fiery inferno, where everything is continuously blasted apart mere instants after it's created, In other words, this happens.Īnd its counterpart, shown below, is no longer happening once the Universe gets cool enough. Even though matter and antimatter are constantly running into one another and annihilating, what's not happening anymore as the Universe ages is that you're not making more matter and antimatter to replace what you're destroying it's all becoming radiation. ![]() And when they do smack into each other, because things are cooling in addition to expanding, they hit each other with less energy. Well, what happens as the Universe expands and cools? Things smack into each other far less often, for one, because there's more space between them in general. ![]() (For those of you wondering just how far back in time I'm talking about, the Universe is about one femtosecond, or 10 -15 seconds, old at this point.) Everything moves away from everything else, just like dots on the surface of a balloon. And while all of this is going on, the Universe is expanding and cooling as it continues to age. For every ten billion antiquarks, there are something like ten billion and six quarks, and for every ten billion positrons, there are ten billion and six electrons. Well, the Universe is still full of hot radiation, flying around and slamming into everything, including nearly equal amounts of both matter and antimatter. So what does our Universe look like at this point? ![]() (If you're just joining us, go back for parts 1, 2, 3, 4 and 5.) Last time, we talked about how we made more matter than antimatter (and we clarified some questions). Welcome back to our series on The Greatest Story Every Told, where we start from before the big bang and come forward in time to get the Universe we have today. Electricity is actually made up of extremely tiny particles called electrons that you cannot see with the naked eye unless you have been drinking.
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