Originally published 29 April 2003
You may have heard of the medieval philosophers who supposedly debated how many angels could dance on the head of a pin. The modern equivalents are surely the astrophysicists who study the beginning and evolution of the universe.
They tell us that the universe is 13.7 billion years old, plus or minus a few hundred million years.
They tell us that a trillion-trillion-trillionth of a second after the big bang, the universe had inflated from a microscopic speck to something large enough to contain every thing we see today.
They tell us that 90 percent of the stuff of the universe is so-called dark matter, invisible particles of a nature yet to be determined.
You have to admire folks who can toss off such statements as if they were talking baseball stats. It’s as if the medieval philosopher answered, “Oh, 7,315 angels, plus or minus 23.”
I once mentioned some of these cosmological assertions to a friend. “Ninety percent of the stuff of the universe is stuff we know nothing about,” I said. He replied, somewhat dourly, “It’s probably the best stuff, too.”
His remark would not have been out of place in the Middle Ages. Folks then, too, believed that much of creation was invisible, and the best stuff, too. Those angels weren’t just dancing on pinheads, they were everywhere.
Is the dark matter of the astrophysicists any different than angels? And why do astrophysicists suppose that dark matter exists?
When astronomers turn their telescopes to galaxies and groups of galaxies, they see stellar motions and gravitational clumping-together that cannot be explained by the gravity of visible matter — stars, galaxies, and luminous nebulas. If the law of gravity is the same in intergalactic space as hereabouts, then something massive and unseen must be pulling on the stars and galaxies: Dark matter.
There are several theoretical guesses for what dark matter might be. One of the best candidates is sluggish, super-massive particles called neutralinos (not the same as neutrinos), whose existence is predicted by a theory called supersymmetry. The theory was invented to unify the laws of physics and explain results of experiments with high-energy particle accelerators, the biggest and most expensive machines in the physicist’s arsenal of instruments. These machines are designed to reproduce in miniature the conditions that existed in the first moments of the big bang.
No one knows if supersymmetry theory is true, but if so, then the Big Bang should have produced just the right number of neutralinos to explain what the astronomers see.
According to astrophysicist David Cline, writing in Scientific American, as we spin our way through the Milky Way galaxy, about a billion neutralinos stream through our bodies every second.
These particles interact with ordinary matter exceedingly rarely. Nevertheless, it should now be possible — just barely! — to detect the dark matter with quantitative, reproducible experiments. A number of experimental groups in the United States and Europe are currently building exquisitely sophisticated instruments to snag a few of the supposed particles that are streaming by the Earth.
If the particles are detected, then we will be confident that gravity as we know it is a universal force. If not, then it’s back to the theoretical drawing board. Says astrophysicist Cline: “The greatest mystery in modern astrophysics may soon be solved.”
If all of this makes your head spin, know that you are not alone. Only a few hundred very smart physicists understand it completely, just as those medieval philosophers who speculated about dancing angels were a band unto themselves.
The difference, of course, is that the dark particles of the astrophysicists will reveal themselves as countable, reproducible blips of energy on the screen of a computer connected to a very clever particle detector. Angels are rather more elusive.
I will leave you with this thought: If the astrophysicists are right in their dark matter speculations, then a thousand neutralinos stream every second through the head of a pin.
To date, neutralinos have not been detected experimentally and remain hypothetical. ‑Ed.
Dark Matter is more likely to go the way of phlogiston, caloric, and polywater, as sensitive experiments confirm the reality of a slight, but measurable change in the value of Newton’s gravitational constant, both diurnally and semiannually, leading to a confirmation of the MOND proposition, and a reassessment of Vera Rubin’s study of galactic rotation curves.
https://www.google.com/url?sa=t&source=web&rct=j&url=https://hal.archives-ouvertes.fr/hal-02867435/document&ved=2ahUKEwiHitSfld36AhW4jYkEHfuyBTsQFnoECA8QAQ&usg=AOvVaw1GnTmKV_GNWOQdf-8D5mr7
If you check the chart of values of Big G..they diverge rather than converge on a single value, consistent with a varying value, depending on what time of day and time of year the measurements were done. Longer runs then yield larger error bars.…a surprise to careful experimentalists.
I too was in high school many years ago, and predicted a varying value of G, depending on variations in the isotropy of the ambient neutrino flux.
That anisotropy, confirmed at the Sudbury Neutrino Observatory, as neutrino lepton fractions oscillate, and resolved the Homestake Mine anomaly for John H Bahcall, causes the slight variation in G seen in these experiments .
Since Earth has an elliptical orbit, simple inverse square law matches the gradual attenuation of the value of G.
Mars, with a much larger eccentricity, should produce a distinctly larger variation, and I submitted a paper to the Gravity Research Foundation Writing Competition, predicting a simple 25 cm pendulum would record approximately 4 more swings per Martian day at aphelion vs perihelion, based on the seen variation at Earth, by Asher G.Gasanalizade.
Betcha a hot fudge sundae?…lol
George
Asger Gasanalizade…typo