Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Wednesday, November 14, 2018

Dark hurricane

There are times that scientists use placeholder names for things they're pretty sure must exist, but haven't identified with sufficient clarity that they can say anything in detail about them.

One example -- that didn't end so well -- is the "ether."  The concept of the ether came about because once Christiaan Huygens, Augustin-Jean Fresnel, and Leonhard Euler made cogent arguments that light had many of the properties of waves, the next question was, "what medium is waving?"  In any familiar sort of wave, there's some sort of medium involved, the particles of which are moving as the wave propagates past.  So, not unreasonably, physicists proposed that there was some sort of medium permeating the universe through which light was propagating, and they called this substance the luminiferous ether.

The problem was, the ether didn't exist, as demonstrated by the Michelson-Morley experiment.  So scientists, scrambling about like mad to save their precious theory, proposed all sorts of convoluted dodges to explain why Michelson-Morley and the ether weren't mutually exclusive, but the whole thing came crashing to the ground when Albert Einstein came up with the Special Theory of Relativity -- which did away with the need for ether.

We have a similar situation right now in physics, except that (being in the middle of it) no one knows how it's going to end -- with a confirmation of an ether-like mysterious substance, or a 21st-century Einstein who proposes a shift in our understanding that makes the entire thing collapse.  I'm referring to dark matter, which was discovered in 1978 by Vera Rubin and Kent Ford because of its gravitational effects.  But this is no minor constituent of the universe; by Rubin and Ford's estimates -- which still hold -- dark matter comprises 85% of the mass of the universe.

The problem is, dark matter, whatever it is, is "non-baryonic" in nature.  Put simply, it does not interact with other matter, and has no effect on light except for the fact that its gravity warps the fabric of the universe and can deflect light's path (a phenomenon called gravitational lensing).

So at this point, we're pretty sure it's there, but no one knows anything about what it actually is.

But this may be about to change.  Last week a paper appeared in Physical Review D claiming that not only are we immersed in dark matter, we are currently in a stream of it (called "S1") that is blowing past us at an unimaginable 500 kilometers per second.  A team led by Ciaran O'Hare of the University of Zaragoza has been analyzing this matter stream, and have concluded that it was generated by the interaction between the Milky Way and a (now-defunct) dwarf galaxy the Milky Way devoured over a billion years ago.  But the remnants are still zooming past us, a dark hurricane light years wide in which we have been immersed without even knowing it until recently.

What the current study suggests is that we might use this to get some long-awaited hard data on dark matter.  Detectors are being set up to detect what are considered the two most likely constituents of dark matter -- WIMPs (weakly-interacting massive particles) and axions (which some theories say could exist in sufficient numbers to account for dark matter).

The problem is, there have been other attempts to find WIMPs and axions, and all have been completely unsuccessful.  In fact, the Wikipedia page on WIMPs (linked above) starts with the unpropitious words, "There exists no clear definition of a WIMP," which to my ears makes it sound like the 19th century physicists' "there's this stuff called ether, and we think it's there, but we can't tell you anything else about it."

The physicists, for their part, are hoping like hell something will come of all this, because if dark matter doesn't exist, it will punch a great big old hole not only in the General Theory of Relativity, but the Standard Model of Quantum Mechanics.  This isn't necessarily a bad thing; look at what the collapse of the ether theory led to.

Um.  The General Theory of Relativity and the Standard Model of Quantum Mechanics.  A little awkward, that.

Of course, I'm a layperson, despite my B.S. in physics.  Far smarter brains than I am are still taking the search for dark matter seriously.  If I was a betting man, though, I'd put money on the likelihood that there's something major we're missing, just as we did with Relativity.  This could lead to great things either way -- which is why this invisible storm is such an exciting discovery.


If you are one of those people who thinks that science books are dry and boring, I'll give you a recommendation that will put that misconception to rest within the first few pages: Sam Kean's The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of Elements.

Kean undertook to explain, from a human perspective, that most iconic of all images from the realm of chemistry -- the Periodic Table, the organized chart of elements from the simplest (hydrogen, atomic number 1) to largest and most complex (oganesson, atomic number 118).  Kean's sparkling prose shows us the personalities behind the science, including the notoriously cranky Dmitri Mendeleev; tragic, brilliant Henry Moseley, a victim of World War I; and shy, self-effacing Glenn T. Seaborg, one of only two individuals to have an element named after them while they were still alive.

It's a fun read, even if you're not a science geek -- maybe especially if you're not a science geek.  Because it allows you to peer behind the curtain, and see that the scientists are just like the rest of us, with rivalries, jealousies, odd and misplaced loyalty, and all the rest of the faults the human race is subject to.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

1 comment:

  1. I believe it is Dark Energy, not Matter, that makes up most of the cosmos, in current thought. That said, both will likely be disproved by 2100.