Comments on Dark Matter and Dark Energy

A reader of my article Big bang fudge factors wrote the following comments:

Dark matter has been detected: neutrinos fit the definition of Weakly Interacting Massive Particles, as they have such small probabilities of interacting with atomic matter that it takes several moles of neutrinos to achieve the same probability of a single interaction as a single neutron or photon. Though individually nearly massless and invisible to matter, the sheer number of neutrinos surrounding us makes it possible to detect them, and makes their combined energy a significant component of the mass of the Universe.

Likewise, Massive Compact Halo Objects are quite ordinary matter. They are planetary and sub-planetary bodies, producing little or no light, and so hard to detect. To these, we add black holes, neutron stars, and brown dwarfs, which also emit little or no light, despite their mass.

Neither should the existence of dark energy be any surprise to Christians. After all, the Bible say, “The heavens are stretched out like a curtain.” Dark energy is the energy of the vacuum state, less than 1 microjoule per cubic meter, distributed uniformly. Only because of the vastness of space are we able to observe its effects. Even so, were this tremendous amount of energy somehow liberated, “the elements shall be consumed by fire.” The decay of the vacuum state, unleashing the tremendous amount of energy stored in it, could very well be the means by which the Lord transforms the Universe at the end of the age.

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Has the dark matter mystery been solved?

Unseen dark matter has been invoked several times to solve problems in astrophysics and cosmology. Historically the most significant problem has been the rotation curves of galaxies, particularly spiral galaxies. Using the Doppler Effect the speeds of the stars and gases in the disk regions of spiral galaxies can be measured. See Fig. 1.

By now hundreds of thousands of galaxies have been measured this way. What is observed is that the speeds of the stars, and the gases beyond where the stars are observed, are much greater than it would appear Newtonian physics allows for.

Figure 1: Edge on spiral galaxy and a rotation curve. Speeds of stars measured from the centre of a galaxy like this, as a function of distance in light-years. Using carbon-monoxide (CO) as a tracer gas the speeds of gas in the rotating disk can be also measured where there are no visible stars (labelled “No Stars”).

As a result it has been suggested that there is an invisible halo of cold non-interacting matter. This putative invisible halo has the needed gravitational effect on the stars and gases but it cannot be seen, hence it is called dark matter. Dark matter is alleged not to be normal atomic matter, made from protons and neutrons (which are known as baryons), but some sort of slowly moving (cold) exotic non-baryonic matter. Weakly Interacting Massive Particles (WIMPs) were suggested. Continue reading

SUSY is not the solution to the dark matter crisis

On August 19, 2016, the “SUSY Bet” event took place in Copenhagen at the conference on Current Themes in High Energy Physics and Cosmology at the Niels Bohr International Academy. An adjudication of the wager on supersymmetry (SUSY) first made in 2000 was given. The detail of wager is explained in the image below.

Supersymmetry

The bet involved two aspects of supersymmetry theory.1

  1. That after 10 years (from 2000) the Large Hadron Collider (LHC) would have collected enough experimental data to confirm or deny the existence of the supersymmetric particles that the theoretical physicists were thinking about at that time.
  2. That supersymmetric particles with sufficiently low masses would be discovered like “sitting ducks” (as Gerard ‘t Hooft put it).

At the event, the Yes side of the bet, who believed the particles would be detected, conceded the loss of the bet to the No side. The bet was meant to be decided on June 16th 2016 if no SUSY particle was detected after effectively 10 years of operation of the LHC. The adjudication of the bet was extended by the ‘No’ side by an addition of 6 years due delays in getting the LHC online, part of which was a delay due to an explosion, which caused a delay of 2 years.

On the larger question of the significance of the negative LHC results, a recorded video statement by Nobel Laureate Gerard ‘t Hooft (who had bet against SUSY) can be viewed above, and a statement by Stephen Hawking (not in on the bet, but in the audience) claimed that if arguments for SUSY were correct, the LHC should have seen something, so they think nature has spoken and there’s something wrong with the idea.
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Dark matter search comes up empty

An online news reportfrom phys.org, titled “Scientists looking for invisible dark matter can’t find any,” reported the following:

Scientists have come up empty-handed in their latest effort to find elusive dark matter, the plentiful stuff that helps galaxies like ours form.

For three years, scientists have been looking for dark matter—which though invisible, makes up more than four-fifths of the universe’s matter—nearly a mile underground in a former gold mine in Lead, South Dakota. But on Thursday they announced at a conference in England that they didn’t find what they were searching for, despite sensitive equipment that exceeded technological goals in a project that cost $10 million to build.

7-scientistslo

Lead co-investigator Richard Gaitskell explains the experiment.

The experiment, called the Large Underground Xenon experiment or LUX, was found to be 4 times its original design sensitivity. It involves a detector that consists of about a third of a ton of supercooled xenon in a tank festooned with light sensors, each capable of detecting a single photon. As the so-called WIMPs (Weakly Interacting Massive Particles) pass through the tank, they should, on very rare occasions, bump into the nucleus of a xenon atom. Those bumps cause the nucleus to recoil, creating a tiny flash of light and an ion charge, both of which are expected to be picked up by LUX sensors.

The experiment is located in a hole a mile (1.6 km) underground in an old gold mine to exclude all sorts of background sources that might give false signals. The alleged dark matter particles are hardly affected by the intervening matter and pass mostly undisturbed through the planet, or so the theory alleges. But alas nothing has been detected. In fact for at least 40 years now no such local lab experiment has found anything.

Scientists are already starting to revamp the South Dakota mine site for a $50 million larger, higher-tech version of LUX, called LZ, that will be 70 times more sensitive and should start operations in 2020, said Brown University’s Richard Gaitskell, another scientific spokesman for LUX.1

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