Big Bang Nucleosynthesis: The First Three Minutes of the Universe
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- Опубликовано: 27 мар 2024
- The story of the universe in its infancy is actually well-known from Classical Physics. Here we mean by Classical, anything that doesn't rely on anything that hasn't been tested in a lab on Earth. We follow the classic book by the same name on a journey back to when the universe was 180 seconds old. We find that there is nuclear fusion in all the cosmos, that it’s so hot nuclei cannot combine, that neutrons and protons are in balance with nuclear reactions. We find that, even more convincing than the cosmic microwave background, the ratio of hydrogen to helium that was fixed in these early moments is greater proof of the Big Bang. This ratio is seen in the most ancient stars, who still carry the original composition of the birth of the universe. We see this wherever we look. It takes will and guts to throw away old religious myths and adopt the reality of creation as it is truly understood.
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The First Three Minutes: A Modern View of the Origin of the Universe by Weinberg:
www.amazon.com/The-First-Three...
Cosmology: A Very Short Introduction: by Coles: www.amazon.com/Cosmology-A-Ver... 
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Gluons actually don't hold nucleons to other nucleons. They hold quarks together into hadrons, but because they have color charge themselves, gluons are just as bound into the hadron as the quarks. Instead, mesons called pions are exchanged between nucleons, and that is what holds the nucleus together. The force is slightly weaker and much shorter range as a consequence. Usually, the gluons are called "the strong force", whereas the pions are called "the strong _nuclear_ force".
Thanks for the correction!
Your lectures truly hit the spot, my first memory is reading about my grandpas encyclopedia about the space and thinking whether it would still count as something even if there was nothing, I think I was 5 years old. A bit later my father introduced me to computers which propelled me to msc of the same subject but now I feel like a kid in the candy store again listening all of this and being spoiled by everything we have learned since, it's truly a marvelous universe we live in.
I'm glad you're enjoying them.
These are a labor of love.
cool trance breaks in the beginning, im an old sckool dj that would make that.
Excellent course. I love it. I've been searching for this material for a very longtime and here it is perfectly presented. Thanks Dr. Kendall.
OH sweet another live episode! im a bit. Late but I watched the intro course then I always go to sleep watching youtube, and for somereason auto play always after two or three hours starts playing the intro to astro videos. so every morning I wake up with equations in my dreams. Its like learning through audio osmosis. Keep up the videos, be glad I dont have your email because gamma decay doesnt make sense like beta or alpha where the neutron proton goes back to the middle of the radio nucleotide that you find on JANUS. So gamma emitters are meta stable but how doe a massless photon get the ration of neutron to protons down to 1:1.5 or 1:2 in trans uranics? Also do you think there is another island of stability up past 118?
How globular clusters are formed out of primordia; matter in the first 3 minutes is mindboggling and how they preserved their relative distance from each other, even though forming a BH from time to time and not disrupting the overall structure is to me the most amazing fact.
This was a great episode, I love these early universe explanations, they always raise other questions in my mind however.
I struggle with photons colliding as the Pauli exclusion principle doesn't apply to photons or gluons as they are massless. Hence we have lasers. Though gluballs seem different again. And weak force bosons require energy for creation, do they take it from the photons or from spacetime itself?
Thoroughly enjoyed it Mr. Kendall, thank you.
Mass is mainly coming from the binding energy holding quarks together. I think less than a 1/8th is from physical matter.
Ending tally, we got photons, hydrogen, helium, deuterium. What about those neutrinos? How many of those roaming around?
Might want to point out that the observable universe was various sizes at different points, but the size of the entire universe was unknowable. Could have been infinite, even at the first microsecond.
RUclips challenge: do the first three minutes in three minute. My cousin greg invented the youtube challenge with the ice bucket when a player for his baseball team ;coach at uConn said als was like ice being dumped on him, then he said dump ice and donate. now we have all kind of challenges, most stupid but some good.
Yoiks! Perhaps I can just speed it up every time I say “So!”
I love how we say; 3 minutes ago. Lovit🌀
Let's go!
So do we have a measure of how quickly the photon energy density decreased over time? Evidently it was much grater than matter's,initially, but must have equaled it at some point.
Do we know what the mean free path of a photon was before recombination? On what scales did it scatter off of matter?
So maybe it's a stupid idea for I've had kicking around is when we smash particles together anti particles are produced right? who's to say they're being produced and not just being unlocked because my thinking is that anti quarks may be able to play nicely with standard quarks if theres 2 normals
What about the the top quarks and strange quarks? They must play at higher energies, why did you ignore them?
What I like a bout the pp chain is that it turns 4p into 2n + 2p….so where is the charge go?
Well the 2 beta+ go annihilate 2 electrons to keep balance. So we have 2e disappear. So where did the 2 units of lepton number go?
That’s left in the 2 neutrinos, so overall, it’s 4e goes to 2e + 2nu
Thanks for the additional clarification
18:24 Is the half-life of the neutron changed by the high energy density? 🤔
(43:50) “Quasars are extraordinarily bright objects”. I thought that it had been settled that quasars are active black holes emissions???
Didn't those guys miscalculate castle bravo mag.😮
Antielectron or Positron?
Same
They are the same thing
Positive electron.
I remember the first 3 minutes. This is not how it happened. Cool story though
An easy way to remember which quarks make up the neutron (Up, Down, Down) is that it can spell out 'DUD', or neutral.
Or that DUU means for sure bro, positively
Or UUD, like the tentacle-face aliens in Doctor Who....
The word “quark” was invented by James Joyce in Finnigan’s Wake, not Milton.🏳️🌈🤨🏳️🌈
So beautifully explained even I understood it. Thank you.