Hydrogen is an element, usually in the form of a gas, that consists of one proton and one electron. Hydrogen is the most abundant element in the universe, accounting for about 75 percent of its normal matter, and was created in the Big Bang. Helium is an element, usually in the form of a gas, that consists of a nucleus of two protons and two neutrons surrounded by two electrons.
Helium is the second-most abundant element in the universe, after hydrogen, and accounts for about 25 percent of the atoms in the universe. Most of the helium in the universe was created in the Big Bang, but it also is the product of hydrogen fusion in stars. However, starlight consists of photons with enough energy to split hydrogen apart, reionizing it back into protons and electrons.
As more and more stars lit up, larger and larger holes of ionization got carved out of the primordial hydrogen clouds. Other, more exotic objects also began forming inside galaxies. Some stars left behind black holes that devoured nearby stars and generated powerful x-ray jets.
In the centers of galaxies, supermassive black holes were growing , with the masses of millions of suns. These events injected huge amounts of energy into the surrounding hydrogen clouds, heating and ionizing them, until, as we look out today, we see that all of the intergalactic hydrogen has been destroyed — reionized into its component particles, protons and electrons.
Using our most powerful optical telescopes, we are finding galaxies so far away that their light, emitted when the universe was only one billion years old, is just now getting to us.
The glimpse we get of these galaxies in the final throes of reionization is as the last remnants of intergalactic hydrogen are being burned away.
Yet as we try to look deeper, the hydrogen itself confounds us. It absorbs the very starlight that we use to observe distant galaxies, acting as a blanketing fog that conceals the chaos behind it. To solve this problem, my colleagues and I designed a new kind of telescope: an array of radio dishes that, instead of searching for distant galaxies, maps the intergalactic hydrogen itself throughout the process of being heated and reionized.
Our Hydrogen Epoch of Reionization Array combines cutting-edge supercomputing hardware with low-cost antenna construction in a unique design that gives it both the sensitivity and precision to create what will be the largest maps in the universe. HERA is sensitive to a specific kind of radio wave produced when the magnetic fields of the proton and electron inside of hydrogen switch their north-south polarity with respect to each other.
Just as two oppositely aligned bar magnets attract each other and release energy in the process, the switching polarity of the electron and proton causes hydrogen to release a small amount of energy. This hyperfine transition produces radio waves with a characteristic wavelength of 21 centimeters. AGE: It is the oldest molecule in the Universe.
It appeared after the Big Bang, more than 13 billion years ago. It is also the fuel of choice for rockets and is already being used to propel electric cars that produce their own power onboard. Hydrogen is used as a reagent in many industries, including oil refining. More than 13 billion years ago, just a few minutes after the Big Bang, the protons that compose the nuclei of hydrogen came into existence.
At this stage in the formation of the Universe, the temperature was extremely high—close to a billion degrees. The Universe then began a phase of expansion and cooling. After several million years, it was sufficiently cold to allow hydrogen molecules to form. A nebula was also behind the origin of the Sun about five billion years ago. Our star is mainly composed of hydrogen and helium, resulting from the thermonuclear fusion reaction that enables it to produce energy.
These two elements are the lightest and the most abundant in the Universe. The four giant gaseous planets in our solar system—Jupiter, Saturn, Uranus and Neptune—are also mainly formed out of hydrogen. However, we do find numerous sources of hydrogen on Earth, where it is combined with other elements, in water and hydrocarbons, for example. Hydrogen was discovered in by British physicist Cavendish. This extremely light gas was in fact hydrogen. He then noticed that burning it produced water vapor steam.
The first fuel cell model was built in a laboratory three years later by Sir William Grove, an English scientist. Thereafter, many other experiments involving the hydrogen molecule were carried out.
His liquefaction process was improved on by another chemist and physicist, the Frenchman Georges Claude, who was also one of the founders of Air Liquide. This was one of the first inventions that allowed humans to take to the skies untethered.
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