James Johnson's List: Origins of the Universe

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• Protons and neutrons come together to form the nuclei of simple elements: hydrogen, helium and lithium. It will take another 300,000 years for electrons to be captured into orbits around these nuclei to form stable atoms.
• After inflation, one millionth of a second after the Big Bang, the universe continues to expand but not nearly so quickly. As it expands, it becomes less dense and cools. The most basic forces in nature become distinct: first gravity, then the strong force, which holds nuclei of atoms together, followed by the weak and electromagnetic forces. By the first second, the universe is made up of fundamental particles and energy: quarks, electrons, photons, neutrinos and less familiar types. These particles smash together to form protons and neutrons.
• The universe begins with a cataclysm that generates space and time, as well as all the matter and energy the universe will ever hold. For an incomprehensibly small fraction of a second, the universe is an infinitely dense, hot fireball. The prevailing theory describes a peculiar form of energy that can suddenly push out the fabric of space. On a rare occasion, a runaway process called "Inflation" can cause a vast expansion of space filled with this energy. The inflationary expansion is stopped only when this energy is transformed into matter and energy as we know it.
• Gravity amplifies slight irregularities in the density of the primordial gas. Even as the universe continues to expand rapidly, pockets of gas become more and more dense. Stars ignite within these pockets, and groups of stars become the earliest galaxies. This point is still perhaps 12 to 15 billion years before the present
• they make up the faint glow of microwaves which bathe the entire universe.

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• The so-called Big Bang theory is the current favoured hypothesis of the formation of the universe according to astronomy.  This asserts that some 12-15 billion years ago there was a suddenly expansion and explosion of all matter and energy out of an original point - out of literally nothing - and that not only space but even time began at this moment.  (So we cannot speak of an explosion in space - because there was no space before, or no time at which this could be measured - space and time being properties of the universe rather than something outside of it).
• According to quantum theory, matter and antimatter particles are created in pairs all the time out of nothing (i.e. vacuum) and cancel each other out with no effect on the universe.  They are therefore called virtual particles).  At the Big Bang, however, massive amounts of matter and antimatter were created and although much of it was similarly cancelled out with a huge release of energy, matter won the day and spawned the universe as we know it.

• This lasted from the initial singularity until 10^-43 seconds after the Big Bang.  That moment is referred to as Planck time.  At that time the universe's size was about 10^-33 cm across. 10^-32 cm to 10^-35 cm is called the Planck width or Planck length or Planck distance.  At this time the quantum wavelength of the universe was larger than the size of the universe itself.  The universe has complete symmetry: all four forces we know today were unified. We do not know what happened before this time, because our knowledge of physics breaks down at this point.   Our present-day formulation of physics fails in principle to be able to explain what was going on.  A quantum theory of gravity is required if we can proceed any farther back toward the beginning.

  • This paragraph may be difficult to understand because humans live in the owrld of meters, seconds, hours, days and years. Anything really small or big becomes hard to comprehend. You don't need to know what the four forces at this time are. You will learn this later in your science careers.
    The easist way to think about the contents of this early universe is as follows:
    You know that when water is cold it is frozen. As is warms the water molecules move faster and fasater and eventually melt. As they heat more they seperate from each other and turn into a gas. If an indivudual water molecule continues to heat the hydrogen and oxygen will rip apart from eath other. As the heating continues the three parts of the atom seperate. This process continues until even the smallest most basic peices of matter are so hot even they cannot stay together to form anything.

• By 10^-32  seconds, >  the universe had expanded to 100 times its original diameter.  At >  this point Inflation stops >
• shortly >  after the Big Bang (10 > ^-35 >  seconds, or 100 billion trillion trillionths >  of a second, to be exact), the universe underwent a period of extraordinarily >  rapid expansion, which lasted until about 10 > ^-33 >  seconds. During >  this time the universe grew exponentially, increasing in diamter a hundredfold >  or more, and in volume  by 10 > > ^30 >  to 10 > ^60 >  times. >

• The Quark-Lepton era begins at 10^-32 seconds after the Big Bang sintgularity (i.e. 1/100,000,000,000,000,000,000,000,000,000,000th of a second, for thos ewho like a lot of zeros). The temperature has cooled to 10¹⁵ degrees Kelvin (1,000,000,000,000,000 degrees).  At this time there are only three fundamental forces, gravity, the strong nuclear force, and the electro-weak force.

  • You do not need to remember these forces in grade nine. You might learn them again if you take science later in your life.
• The universe was still so hot that even when matter and anti-matter particles collided and annihilated each other (as they constantly did) they would automatically reform.  The universe was pervaded by a sort of quark soup. 

  However the universe was still expanding and hence cooling.  By the time a one millionth of a second had passed since the original singularity, the universe was about the same diameter as the Solar System is now (only it was a 4 dimensional hypersphere rather than a sphere such as we can comprehend).  The temperature had dropped to 1,000,000,000,000 degrees Kelvin.  It was no longer hot enough to maintain the creation and annihilation of quark-anti-quark pairs and so quarks freeze out of the universe.  From this moment on they could only occur as pairs or triplets, never alone
• As the energy drops further the heavy particles known as baryons (protons and neutrons) freeze out.  The energy density is no longer sufficient to create and maintain protons. 
• For the next second (notice how things are slowing down...), electrons, which are much smaller than protons, remain in energy equilibrium with the universe.  This period is known as the Electron Era.  The universe is now quite huge (a light year and growing), but the temperature is dropping as heat has to be distributed through a larger and larger volume

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• The Radiation Era began two or three minutes to 300,000 years after the Big Bang, with a process known as nucleosynthesis.  This was when helium nuclei (in fact all the helium nuclei in the universe) were formed out of protons.  So this is the initial start of the atomic kingdom.
• This is the same ratio that is found in stars today, (except for the heavier elements produced later ) which argues in favour of the Big Bang theory
• For the rest of the Radiation Era (a period of 300,000 years) the universe remained fully ionized, and continues to expand. The entire universe was a plasma of freely moving protons, neutrons, and electrons, just as one finds in stars today.  Plasma, considered the fourth state of matter (after solid, liquid, and gas) is a state of charged ions (atomic nuclei) and electrons; with photons scattering off them and reionized any atoms that had formed.  There are no atoms as exist normally - i.e. electrons orbitting a nucleus, because the heat is so great that any electrons are automatically stripped away.

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• It began 300 to 500 thousand years after the Big Bang, when the temperature of the background radiation had dropped to around 3000 degrees K, cooler than the surface of the sun, but still hot enough to melt and vaporise most subtsances
• When the temperature dropped to about 3000 K, it was cool enough for electrons to form into atoms with the hydrogen and helium nuclei.  The previous state of plasma no longer ensured
• Electrons and protons recombine into hydrogen atoms, and matter as we know it, with electrons circling atomic nucleis, appears.
• matter to collapse into stars and galaxies under gravitational attraction.
• The first generation of stars (population III) formed from clouds of interstellar gas.  Thus began the Stelliferous era.  Massive stars create the chemical elements within their cores and return them to the interstellar medium when they explode as supernovae.   There is a period of element formation that lasts for some 100 million to one or two billion years.

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• After the Big Bang, the Universe was an incredibly hot fireball,
• Not only that, but by measuring this pattern across all of the sky, astronomers can calculate the shape and size of the whole Universe

• Because of its name many people think of the Big Bang as a kind of explosion that happened at some specific point in space, but this isn't correct, as the Universe didn't spring from one central ignition point. Instead, during the Big Bang space was first created and then stretched

• The steady state theory of cosmology  claims that the Universe simply exists without changing with time. This theory  presents many physical as well as philosophical difficulties. Evidence suggests that  the Universe is expanding. While  there are ways to explain expansion in a steady state universe, few astrophysicists  believe this theory, because there is little evidence to support it. As the first  widely held theory about the Universe it is included here for historical completeness.

• The idea of a static universe is one which demands that space is not expanding nor contracting but rather is dynamically stable. Albert Einstein proposed such a model as his preferred cosmology by adding a cosmological constant to his equations of general relativity to counteract the dynamical effects of gravity which in a universe of matter would cause the universe to collapse. After the discovery by Edwin Hubble that there was a relationship between redshift and distance, Einstein declared this formulation to be his "biggest blunder".^[1]

   

  Even after Hubble's observations, Fritz Zwicky proposed that a static universe could still be viable if there was an alternative explanation of redshift due to a mechanism that would cause light to lose energy as it traveled through space, a concept that would come to be known as "tired light". Subsequent cosmological observations have shown such a model to be an unviable alternative, leading most astrophysicists to conclude that the static universe is essentially falsified.