The Entire History of the Universe in 20 Minutes

 

CHAPTERS: 0:00 What this video is about 0:54 History of major cosmological discoveries 3:31 How modern Cosmology started with Einstein 6:04 All about the singularity 7:49 Timeline of 6 stages of the formation of the Universe 8:56 Cosmic Inflation 9:30 Elementary particle formation 10:15 Nuclei formation 11:00 Recombination: Atoms formed, CMB 12:01 How stars, planets and galaxies formed 15:00 Dark Matter 16:33 Dark Energy 17:50 Learn more on Wondrium

SUMMARY:

All cosmology: A brief history of the universe, from the Big bang to today by Arvin Ash. Our view of modern Cosmology has largely been shaped by discoveries made over only about the last 100 years. 

1920s - Edwin Hubble discovered galaxies outside our own Milky Way, and that the universe is expanding. 1949 - Fred Hoyle coined the term “Big Bang.” 

Penzias and Wilson discovered the Cosmic Microwave Background, or CMB, which is strong evidence for the Big Bang.
1970s - Vera Rubin found evidence for dark matter.
1980s - Alan Guth developed the theory of Cosmic Inflation.
1990’s - Evidence of dark matter was discovered. 

2015 - Gravitational waves were detected.

But modern cosmology began with Einstein’s formulation of the theory of General Relativity. 

So what is it? It described how mass and energy could change the underlying space and time itself. And this change is what manifests as gravity. Plugging everything into the equations gives us a model of our universe. We know our visible universe is expanding, so this means that if we turn back time, it will become smaller and smaller. So at some point, it should be infinitely small. This is called the singularity. This may not be real, but we know the early universe was very dense and hot. It was compressed to a very small size, about the size of a swimming pool. How can the entire universe fit into the size of a swimming pool? The universe was all energy, no particles. And energy has no size limit. The temperature is just very high at smaller volumes. The timeline of the universe can be divided into about 6 stages. 

The first stage at t=0, is the birth of the universe started from perhaps a singularity 13.8 billion years ago.  

Stage 2 is cosmic inflation at t=10^-36 seconds. The temperature is 10^32 Kelvin. 

Stage 3 is when elementary particles formed at t= 10^-11 seconds. The temperature cooled to 10^18K. 

Stage 4 is when nuclei formed at t=180 seconds, temperature was 1 billion Kelvin.
Stage 5 is Recombination, when atoms formed at t=380,000 years. Temperature was 3000 K. The first light of the universe can be detected at this point, called the cosmic microwave background or CMB.
Stage 6 is when stars, galaxies and larger structures formed.

Minor temperature differences can be detected on the CMB. This is what provided the seeds for large scale structures of the universe. Stars formed when gas clouds consisting of hydrogen and helium combined and gravitational pressure increased over time. Eventually, the pressure condensed the ball of gas and ignited forming stars. Elements heavier than helium formed in the cores of early stars, which exploded in supernovae explosions to form successive generations of stars. Our sun formed when a gravitational clump formed somewhere within a cloud of gas or nebula, consisting of prior supernovae explosions. When it got heavy enough to fuse hydrogen in its core, began to shine. The leftover debris from the sun’s birth consisting of heavier elements formed a proto-planetary disk which accreted over time to form the planets. That’s how the earth was formed. Galaxies are vast collections of stars like our sun. They also contain significant amounts of gas and dust. But these visible forms of matter do not appear to have enough mass to keep most galaxies gravitationally bound together. Calculations suggest that up to 5X more mass forms an invisible halo around galaxies and galaxy clusters that keeps them gravitationally bound. This is known as dark matter. Galaxies spin due to conservation of angular momentum. The rotation is also why galaxies are generally flat. If you take any object and spin it, it will flatten. The exact details of why we have the different galaxy types are not fully known. #cosmology #bigbang There is something that accounts for more than two thirds of all the energy we observe in the universe. It's dark energy which is like an anti-gravity force that pervades all of spacetime. It is accelerating the expansion of the universe. So in the early universe, where dark matter dominates, the attractive force of gravity reigns supreme, and things got together and formed structures. But as the universe aged, dark energy became more dominant, and made things move further away from each other. And there seems to be nothing that will stop the universe from expanding at an ever accelerating pace.

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Quran:  1444 Years ago

اَوَلَمْ يَرَ الَّذِيْنَ كَفَرُوْٓا اَنَّ السَّمٰوٰتِ وَالْاَرْضَ كَانَتَا رَتْقًا فَفَتَقْنٰهُمَاۗ وَجَعَلْنَا مِنَ الْمَاۤءِ كُلَّ شَيْءٍ حَيٍّۗ اَفَلَا يُؤْمِنُوْنَ

Have those who disbelieved not considered that the heavens and the earth were a joined entity, and then We separated them and made from water every living thing? Then will they not believe? [Quran: Al-Anbya 21: 30]

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يَوْمَ نَطْوِى السَّمَاۤءَ كَطَيِّ السِّجِلِّ لِلْكُتُبِۗ كَمَا بَدَأْنَآ اَوَّلَ خَلْقٍ نُّعِيْدُهٗۗ وَعْدًا عَلَيْنَاۗ اِنَّا كُنَّا فٰعِلِيْنَ

The Day when We will fold the heaven like the folding of a [written] sheet for the records. As We began the first creation, We will repeat it. [That is] a promise binding upon Us. Indeed, We will do it. [Quran: Al-Anbya 21:104]

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The Trouble with Gravity: Why Can't Quantum Mechanics explain it?

SUMMARY: In a classical universe, if we knew all the positions and velocities for all particles, we could predict the future and the past. Quantum mechanics is not like this. It shows that reality is not deterministic but is probabilistic. The precise location of a particle cannot be predicted in advance, even in principle. This is the most accurate theory we have. It can account for all the forces of nature, except gravity. Why is gravity so different? Why can’t gravity be modeled by quantum mechanics? Why is Quantum Gravity so difficult? General Relativity is very accurate, so why must we quantize gravity? Because quantum mechanics works. And General relativity falls apart at quantum scales. Quantum mechanics says that particles are not like little cannon balls but are like a wave described by a wave function. Particles are waves until some kind of interaction occurs, at which point the wave becomes localized like a particle. But prior to this, we can't predict the location of the particle. But a photon or electron, just like any quantum particle must also have a gravitational effect because that's what General Relativity says. But if it's a wave prior to an interaction, and it could be anywhere until the moment we measure it, where is its gravitational effect located? General Relativity can't tell us where. We don’t know how this works because we don’t have a quantum description of gravity.

So the bottom line, we know quantum mechanics works well at the smallest scales. 

And we know that General Relativity works well at large scales. 

But the problem is that general relativity does not work at the smallest scales. This cannot be because gravity must work at the smallest scales, otherwise its cumulative effects would not work at large scales. This is why most physicists think General Relativity must be brought into the fold of quantum mechanics. According to Quantum mechanics, all interactions between matter particles are mediated by the force particles. And all these interactions happen with space and time as the background. Gravity doesn’t fit this picture because in general relativity, gravityis due to a warping, or curving of the background spacetime itself. There is no force-carrying particle in general relativity which mediates gravity between matter particles. This does not mean that General relativity is wrong, it is just incomplete. Why is quantizing gravity so difficult? The short answer is because we get infinities when we try to incorporate gravity in quantum mechanics equations. Where are these infinities coming from? When an electron and a positron annihilate to create an energetic photon, which then converts back to an electron and a positron, quantum uncertainty is such that the photon on its way to turning into an electron and positron, can convert to any one of a number of different number of particles, for example it can turn into a top quark and anti top quark which annihilates, or it can turn into an electron and positron and back into a photon, or something else. And it can do this 10 times, 100 times, 1000 times, or an infinite number of times before turning into an electron and positron again. When describing this mathematically, we have to take all the momentums of all the particles and all potential interactions between the various particles into account. There turns out to be an infinite number of combinations of interactions . This is where the infinities crop up in the equations of quantum mechanics. However, this problem can be solved in quantum mechanics by something called renormalization. #quantumgravity But renormalization does not work with gravity because instead of just considering all the particles that the photon can turn into, and their interactions, we also have to take into account all the gravitational effects. But just because we can’t solve it does not mean that solutions don’t exist. They probably do, but a completely new approach is needed. Two popular approaches are Loop Quantum Gravity and String Theory.

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Edited by CFC