Cosmic timeline 07

The Hadron Epoch
In physical cosmology, the hadron epoch was the period in the evolution of the early universe during which the mass of the Universe was dominated by hadrons. It started approximately 0.000001 seconds after the Big Bang, when the unimaginable heat of the universe had dropped to a temperature that would allow the quarks from the preceding quark epoch to bind together into hadrons.

Initially the temperature was high enough to allow the formation of hadron/anti-hadron pairs, which kept matter and anti-matter in a sort of equal balance.

But what is anti-matter?
The modern theory of antimatter begins with a paper by Paul Dirac in 1928 who realised that his developing scientific theory was predicting the possibility of anti-electrons. These were discovered by Carl Anderson in 1932 and named positrons. So, in particle physics, antimatter is about the idea of the antiparticle to matter, where antimatter is composed of antiparticles in the same way that normal matter is composed of particles.

These ideas help cosmologists thinking about the Big Bang beginnings of our universe.

So, returning to the hadron epoch, as the temperature of the universe continued to fall, hadron/anti-hadron pairs were no longer produced. Most of the hadrons and anti-hadrons were eliminated as they interacted in what are termed annihilation reactions, leaving a small quantity of hadrons. The elimination of anti-hadrons was completed by one second after the Big Bang, when the following lepton epoch began.

Anti-matter and popular imagination
The novel Angels & Demons, by Dan Brown, involves antimatter created at the Large Hadron Collider to be used in a weapon against the Vatican. In response CERN published a “Fact or Fiction?” page discussing the accuracy of the book’s portrayal of the LHC, CERN, and particle physics in general. The movie version of the book has footage filmed on-site at one of the experiments at the LHC; the director, Ron Howard, met with CERN experts in an effort to make the science in the story more accurate.


This is what CERN say:
Do you make antimatter as described in the book?

No. The production and storage of antimatter at CERN is not at all as described in the book: you cannot stand next to the Large Hadron Collider (LHC) and see it come out, especially since the LHC accelerator is not yet in operation.

To make antiprotons, we collide protons at nearly the speed of light (to be precise, with a kinetic energy of about 25 GeV) with a block of metal, e.g. copper or tungsten. These collisions produce a large number of particles, some of which are antiprotons. Only the antiprotons are useful, and only those that fly out in the right direction. So that’s where your energy loss goes: it is like trying to water a pot of flowers but with a sprinkler that sprays over the whole garden. Of course, we constantly apply new tricks to become more efficient at collecting antiparticles, but at the level of elementary particles this is extremely difficult.

Why then do you build the LHC?

The reason for building the LHC accelerator is not to make antimatter but to produce an energy concentration high enough to study effects that will help us to understand some of the remaining questions in physics. We say concentrations, because we are not talking about huge amounts but an enormous concentration of energy. Each particle accelerated in the LHC carries an amount of energy equivalent to that of a flying mosquito. Not much at all in absolute terms, but it will be concentrated in a very minute volume, and there things will resemble the state of the universe very shortly (about a trillionth of a second) after the Big Bang.

The novel FlashForward, by Robert J. Sawyer, involves the search for the Higgs boson at the LHC. CERN published a “Science and Fiction” page interviewing Sawyer and physicists about the book and the TV series based on it.

Two hadrons collide, creating a shower of subparticles. Such an ‘event,’ as physicists term it, should produce evidence of the Higgs boson, if current theory is correct.


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