Formation of Hydrogen in

the early Universe:

Alexia Noirot UVI-5

Hydrogen is probably one of the most important elements on our planet followed by Carbon and Oxygen. Binding with Oxygen we get water, binding with carbon we get many of the organic molecules that make up our body. About 90% of the atoms and 75% of elemental mass of the universe is hydrogen.

But why are we concerned with knowing how much hydrogen there is in the universe? What does it matter to us?

The large abundance (amount) of Hydrogen in the universe has puzzled astrophysicists for many years, but it is the Big Bang Theory that can explain this large abundance.

The big bang theory states that the universe started out in a very hot, dense state (perhaps infinitely hot and infinitely dense) and has been expanding ever since. Immediately after the big bang, the universe was too hot and too dense for elements to form. Hydrogen didn’t appear until the universe had expanded and subsequently cooled enough for the first protons and neutrons, and later simple atoms, to form. Between about 10^-12 (ten to the power of minus twelve) and 10^-6 seconds after the Big Bang, neutrinos, quarks, and electrons formed. These are part of the Standard model: a model used by physicists to show every fundamental particle known to mankind of which further particles are made of. For example, quarks are part of the standard model but protons are not because they are made of quarks (two up quarks and one down quark, written uud) and likewise neutrons are made of two down quarks and one up quark (udd) - to read more about this check the article linked at the bottom. As the universe cooled, the quarks condensed into nucleons (protons and neutronscomponents of the atomic nucleus). This process is similar to the way that steam condenses to liquid droplets as water vapour cools. Protons and Neutrons began forming, from around 10^-6 to 1 second after the big bang. Within about three minutes, the Universe cooled enough to around 1 trillion degrees Kelvin, the quark plasma cooled to a Hadron gas where protons and neutrons could fuse to form hydrogen and some helium nuclei, this is called nucleosynthesis. But after about 20 minutes, nucleosynthesis ended and no further nuclei could form.

The problem at this point was that electrons couldn’t stay in orbit around any atomic nucleus because of the immense heat and radiation still flooding the universe. Shortly after any neutral atoms would form (neutral atoms contain the same number of protons and electrons, and thus carry no overall charge), they were knocked apart again by energetic radiation. Finally, after 380,000 years or so, the universe had again expanded and cooled enough for conditions to favour electrons staying in orbit around atomic nuclei. This is when recombination occurred neutral hydrogen (and helium) finally appeared because they could “recombine with” (hold on to) electrons without easily losing them to stray radiation.

The majority of the helium in our universe is Helium 4, this is its most stable isotope. The vast majority of this was formed through the recombination of electrons with pre-existing helium nuclei. However, large amounts of new helium is being created by nuclear fusion of hydrogen in stars. It takes four hydrogen atoms to fuse into each Helium nucleus. Fusion is a difficult process to mimic on earth but the conditions on stars, like our Sun, is perfect The stellar core is around 14 million Kelvin, a substantial energy barrier of electrostatic forces must be overcome before fusion can occur. The repulsive force between two positive protons must be overcome, this requires lots of energy and pressure which is provided by the conditions on the Sun and sun like stars. Hydrogen ‘burning’ initiates the energy source of stars and leads to the formation of Helium.

Immense amounts of energy is released from the process of fusion. The process releases energy because the total mass of the resulting single nucleus is less than the mass of the two original nuclei. The leftover mass becomes energy. Probably the most well known equation in physics - E=mc2 - can be used to describe this. ‘M’ denotes the missing mass in the helium nuclei, ‘c squared’ denotes the speed of an electromagnetic wave (3 x 10 ^8 squared, equal to 9 x 10^16) and ‘E’ is the energy that any mass has at rest If E and m are proportional, c^2 is the proportionality constant which describes how a tiny amount of mass can be converted into enormous amounts of energy

In summary, hydrogen was created very early on in the lifeline of the universe. Despite the fact that 380,000 years seems like a huge amount of time, the universe has been around for approx 13.8 billion years. The process of fusion forms helium and all other elements known to mankind. Masses of pressure are needed to force nuclei together and this has not been replicated on earth yet, but once we have figured out how too it has potential to be a massive power source.

If this process could be mimicked on earth, it has great potential to solve the clean energy crisis on our hands.

● More information on the Standard model: https://home.cern/science/phys ics/standard-model

Superfluidity

Siena Woolf UVI-8

A superfluid is a frictionless or zero viscosity fluid; it flows without any loss of kinetic energy and when it is stirred, it forms vortices (whirlpools) that continue to rotate indefinitely. They will do that because of its frictionless characteristic. Superfluids occur in two isotopes (equal number of protons but different number of neutrons in the nucleus) of helium, He-3 and He-4, when they are liquified to cryogenic temperatures from -150ºc to Absolute Zero (-270ºc). This temperature is where molecular motion ceases to occur.

Superfluids also exhibit the so-called “fountain effect” where a container with a superfluid empties itself spontaneously. Superfluids can also be in perpetual motion as a fountain which can be seen in a video.4

Superfluids are often related in conversation to Bose-Einstein Condensates (BECs). They are similar because a BEC is when a state of matter - that is typically formed when a gas of bosons at very low densities - is cooled to temperatures close to Absolute Zero. A boson is a type of particle that includes the photon as well as atoms such as He-4. These condensates can share a quantum state5 and were first predicted in 1924-1925 by Albert Einstein who was following and crediting Satyendra Bose in the new field which is now known as Quantum Physics. Einstein proposed that cooling bosonic atoms to a very low temperature would cause them to fall/”condense” into the lowest accessible quantum state, resulting in a new form of matter (the Fifth state of matter). The important thing to remember is that not all BECs are superfluids, and not all superfluids are BECs.

A superfluid creeps up the walls of the cup's wall and comes down on the outside forming a drop. This continues until the cup is empty

The History of superfluidity begins in 1908 when physicist Dr Onnes liquified Helium, which is usually in the state of matter of gas. The melting point of He is -272.2ºC and the boiling point is -268.9ºC. The boiling point is reached before the melting point and so in 1910, Onnes discovered that when Helium was cooled below 2.2ºK, it abruptly stops boiling.

4 https://www.youtube.com/watch?v=UNpKCYZFfDU

5 A quantum state is any of various states of a physical system (such as an electron) that are specified by particular values of attributes (such as charge and spin) of the system and are characterised by a particular energy Merriam-Webster.com

Further, in 1923, Onnes, and another physicist, Dana, measured Helium's specific and latent heat and observed a strange discontinuity in the process which they failed to explain.6 Later, in 1935, Doctors Wilhelm, Misenerand, and Clark measured the viscosity of liquid helium with a torsion pendulum and found that the viscosity sharply decreased below the lambda point. Furthermore, in 1935, Kapitsa also worked on the viscosity of the superfluid below the lambda point Kapitsa had an intuition that He-II had something in common with superconductors, but during his work, he was taken by Stalin to work on the USSR's nuclear arsenal.

Similarly, Lev Landau was also working on superfluids, but he was arrested for being an author of a leaflet criticising the Soviets. Landau was born in Baku and studied at the Leningrad Physico-Technical Institute where he worked among many scientists. He also worked in

6 Keemson and Wolfke were also working on liquid helium, but it was not until 1927 that they identified a transition between the two phases at 2.17ºK and named it Helium-I above it and Helium-II below, the transition was known as the Lambda Line.

Copenhagen under Niels Bohr who is renowned for proposing the theory for the Hydrogen Atom; that Electrons move around a nucleus, but only in prescribed orbits, and if electrons jump to a lower-energy orbit, the difference is sent out as radiation. Landau’s work branches through fluid mechanics and quantum field theory, and a large portion of his papers refer to the theory of the Condensed state. After Kapitsa’s discovery of the superfluidity of liquid Helium, Landau’s research led him to construct the complete theory of quantum liquids at very low temperatures. He consequently won the Nobel Prize in 1962 “For his pioneering theories for condensed matter, especially liquid helium”

Superfluids are also slightly controversial when discussing the Second Law of Thermodynamics (SLT). The law stands as “the entropy of an isolated system always increases”, in other words, as energy is transferred or transformed, more and more energy is wasted. But, Physicist Dr Yongle Yu has found a possible loophole in which entropy actually decreases with time.7 This is because the SLT does not correspond to a built-in rule in Quantum Mechanics, and so Dr Yu argues that it is quantum mechanics rather than the SLT which governs nature. In an equation, it can be shown that superfluid He-4 contradicts the SLT and that it is possible to convert thermal energy in the environment into useful energy.

7 https://arxiv.org/pdf/1611.02566.pdf

Researchers at the Argonne Laboratory say that they have found a loophole to show that entropy does decrease on a microscopic scale and only in the short term. These researchers studied the H-theorem on a quantum scale, more is explained: https://www.sciencealert.com/physicis ts-say-they-ve-found-a-way-to-break-th e-second-law-of-thermodynamics The ultimate goal is to develop scientific models that unify quantum mechanics with gravity This is known as Grand Unified Theory, where all forces are “unified”, since quantum mechanics already unifies three of the four known fundamental interactions which are the Electromagnetic, Weak, and Strong. This can be seen through Superfluid Vacuum Theory (SVT), where the fundamental physical vacuum is viewed as a superfluid or a Bose-Einstein Condensate. In space, dark matter and particles are substances that flow with zero friction, and SVT could explain how atoms move at similar temperatures in space. Currently, researchers are looking at nebulas with high energy x-rays and gamma rays with hopes that changes in the radiation as it travels to Earth will prove the theory of the Superfluidity of space.