Twinkle, twinkle, little antistar

It's a big mystery why anything exists.

I'm not just being philosophical, here.  According to the current most widely-accepted cosmological model, when the Big Bang occurred, matter and antimatter would have formed in equal quantities.  As anyone who has watched Star Trek knows, when matter and antimatter come into contact, they mutually annihilate and all of the mass therein is converted to a huge amount energy in the form of gamma rays, the exact quantity of which is determined by Einstein's law of E = mc^2.

So if we started out with equal amounts of matter and antimatter, why didn't it all eventually go kablooie, leaving a universe filled with nothing but gamma rays?  Why was there any matter left over?

The answer is: we don't know.  Some cosmologists and astrophysicists think that there may have been a slight asymmetry in favor of matter, driven by random quantum fluctuations early on, so while most of the matter and antimatter were destroyed by collisions, there was a little bit of matter left, and that's what's around today.  (And "a little bit" is honestly not an exaggeration; the vast majority of the universe is completely empty.  An average cubic meter of space is very unlikely to have much more than an atom or two in it.)

One question this sometimes brings up is whether the stars and galaxies we see in the night sky are matter; if, perhaps, some entire galaxies are made of antimatter, and there really are equal amounts of the two.  After all, antimatter is predicted to act exactly like matter except that its fundamental particles have the opposite charges -- its protons are negative, its electrons positive, and so forth.  So a planet entirely formed of antimatter would look (from a safe distance) exactly like an ordinary planet.

And just to throw this out there, an antiplanet wouldn't have copies of all of us except for having the opposite personalities, for example some people who are good guys being evil and/or having beards, as outlined in the highly scientific Lost in Space episode "The Antimatter Man:"

Nor would there be a creepy bridge between the two universes, covered with fog and backed by eerie music:

Which is a shame, because I always kinda liked that episode.

Considerations of evil Major Don West with a beard notwithstanding, here are two arguments why most physicists believe that the stars we see, even the most distant, are made of ordinary matter.  The first is that there is no known process that would have sorted out the matter from the antimatter early in the universe's life, leaving isolated clumps of each to form their respective stars and galaxies.  Secondly, if there were antistars and antigalaxies, then there'd be an interface between them and the nearest clump of ordinary stars and galaxies, and at that interface matter and antimatter would be constantly meeting and mutually annihilating.  This would produce a hell of a gamma ray source -- and we haven't seen anything out there that looks like a matter/antimatter interface (although I will return to this topic in a moment with an interesting caveat).

A paper last year found that the key to understanding why matter prevailed might lie in the mysterious "ghost particles" called neutrinos.  There are three kinds of neutrinos -- electron neutrinos, muon neutrinos and tau neutrinos -- and one curious property they have is that they oscillate, meaning they can convert from one type to another.  The rate at which they do this is predicted from current theories, and it's thought that antineutrinos do exactly the same thing at exactly the same rate.

The experiment described in the paper took place in Japan, and found that there is an unexpected asymmetry between neutrinos and antineutrinos.  Beams of muon neutrinos and muon antineutrinos were sent on a six-hundred-kilometer journey across Japan, and upon arriving at a detector, were analyzed to see how many had converted to one of the other two "flavors."  The surprising result was that the neutrinos had oscillated a lot more than predicted, and the antineutrinos a lot less -- something called a "CP (charge-parity) violation" that shows antimatter doesn't, in fact, behave exactly like matter.  This asymmetry could lie at the heart of why the balance tipped in favor of matter.

But now a new analysis of data from the Fermi Gamma-ray Space Telescope has thrown another monkey wrench into the works.  The study was undertaken because of a recent puzzling detection by an instrument on the International Space Station of nuclei of antihelium, which (if current models are correct) should be so rare in the vicinity of ordinary matter that they'd be entirely undetectable.  But what if the arguments against antistars and antigalaxies I described earlier aren't true, and there are such odd things out there?  Antistars would be undergoing fusion just like the Sun does, and producing antihelium (and other heavier antielements), which then would be shed from the surface just like our Sun sheds helium.  And some of it might arrive here, only to fall into one of our detectors.

But what about the whole gamma-rays-at-the-interface thing?  Turns out, the study in question, the subject of a paper last week in the journal Physical Review D, found that there are some suspicious gamma-ray sources out there.

Fourteen of them, in fact.

These gamma-ray sources are producing photons with an energy that's hard to explain from known sources of gamma rays -- pulsars and black holes, for example.  In fact, the energy of these gamma rays is perfectly consistent with the source being ordinary matter coming into contact with an antistar.

Curiouser and curiouser.

It doesn't eliminate the problem of why the universe is biased toward matter; even if these are antistars, their frequency in the universe suggests that only one in every 400,000 stars is an antistar.  So we still have the imbalance to explain.

But it's a strange and fascinating finding.  Astrophysicists are currently re-analyzing the data from every angle they can think of to try and account for the odd gamma-ray sources in any way other than it being evidence of antistars, so it may be that the whole thing will fizzle.  But for now, it's a tantalizing discovery.  It brings to mind the famous quote from J. B. S. Haldane -- "The universe is not only queerer than we imagine, it's queerer than we can imagine."

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When people think of mass extinctions, the one that usually comes to mind first is the Cretaceous-Tertiary Extinction of 66 million years ago, the one that wiped out all the non-avian dinosaurs and a good many species of other types.  It certainly was massive -- current estimates are that it killed between fifty and sixty percent of the species alive at the time -- but it was far from the biggest.

The largest mass extinction ever took place 251 million years ago, and it destroyed over ninety percent of life on Earth, taking out whole taxa and changing the direction of evolution permanently.  But what could cause a disaster on this scale?

In When Life Nearly Died: The Greatest Mass Extinction of All Time, University of Bristol paleontologist Michael Benton describes an event so catastrophic that it beggars the imagination.  Following researchers to outcrops of rock from the time of the extinction, he looks at what was lost -- trilobites, horn corals, sea scorpions, and blastoids (a starfish relative) vanished completely, but no group was without losses.  Even terrestrial vertebrates, who made it through the bottleneck and proceeded to kind of take over, had losses on the order of seventy percent.

He goes through the possible causes for the extinction, along with the evidence for each, along the way painting a terrifying picture of a world that very nearly became uninhabited.  It's a grim but fascinating story, and Benton's expertise and clarity of writing makes it a brilliant read.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Ground state

It's been a while since we've looked at bizarre alt-med health claims, so I was excited to stumble on an article in WellnessMama called "How to Get Healthy While You Sleep: How to Use Earthing & Grounding to Boost Health."

We're put on notice right away in the first paragraph when we read the following:

I’ve been self-testing an innovative new way (inspired by a very old way) of reducing stress and improving sleep lately and I now feel like I have enough personal data to pass on my results to you.

Because if there's anything that we find out from any reputable scientist, it's that the plural of "anecdote" is "data."  But this is only the beginning of the issues with this article, so we'll let that be for the moment.

The next thing she tells us is that we would all benefit from coming into direct contact with the ground regularly, i.e., walking barefoot.  I'm certainly not opposed to that; in fact, when the weather is warm, I tend to wear the legally permissible minimum amount of clothing, and in fact have been known to enjoy a nice skinnydip in my pond at times when no one is looking.  But wait till you find out why she thinks that going barefoot is good for you:

Basically, the theory is that our bodies are meant to come into contact with the Earth (a “grounding” force) on a regular basis. Positive electrons in the form of free radicals (ever heard of those guys?) can build up in our bodies and direct contact with the ground balances this out as it is a negative grounding charge. 

Our bodies and cells have electrical energy, and especially with the high prevalence of Electromagnetic waves, Wi-Fi and mobile phone waves, many of us have a high amount of positive electrons built up in our bodies.

"Positive electrons" do exist, by the way.  They're better known to physicists as "positrons."  But there's one problem with her claim, and that is that positrons are actually antimatter.  If your body built up a "high amount of positive electrons," they would come in contact with the plain-old-garden-variety negative electrons in your body, self-annihilate, and you would explode in a flash of gamma rays.

Which honestly sounds worse than being stressed and sleepless.

[image courtesy of CERN and the Wikimedia Commons]

Oh, but it's all real, she assures us:

At first I was skeptical that something so simple could work but after researching it... it seemed at least plausible that it would work.  I also ran the idea by some electrical engineer friends and a friend who has done research in the biomedical field and they confirmed that there was some science to back it up.

So let me get this straight; you told some electrical engineers and biomedical researchers about your body building up positive electrons, and how those were the same thing as free radicals, and they said that this all made sense?

Where did your friends get their degrees, Big Bob's Discount Diploma Warehouse?

Then we hear some of her evidence that this works:

Have you ever noticed that you sleep better on a beach vacation after walking in the sand or being in the ocean?  The sand and ocean water and both naturally conductive materials and both help ground the body and remove excess positive electrons.  For the same basic reason that we ground electrical outlets to avoid the build up of excess positive charge, our bodies need the same ground effect.

No, I think I sleep better while on vacation because I don't have to spend every spare minute thinking about lesson plans and grading papers.  And we don't ground electrical outlets to "avoid the buildup of excess positive charge," it's so that if there's a short in the wiring, the current will divert harmlessly rather than electrocuting you or burning your house down.

Or did you learn about that from your electrical engineer friends, too?

Then we hear all about the things that walking barefoot can cure, which include high blood pressure, insomnia, muscle aches, headaches, jet lag, bedsores, and (I'm not making this up) snoring.

Bet you didn't know that snoring was caused by excess positrons in your nasal cavity, did you?  I sure didn't.

In any case, the reality is that even if you wear rubber-soled shoes -- hell, you could wear an entire rubber suit if you wanted -- you ground yourself every time you touch a faucet (or anything metallic that's in contact with the ground) with your bare hand.  It's the principle of the carpet shock; you do sometimes build up a static charge (it could be positive or negative) on your body, but if you brush against a grounded object, the excess electrons will jump one way or the other and you're going to become neutral with respect to that grounded object.

Because that's the way electricity works.

Then she goes into how we should not only all walk barefoot, we should buy "grounding mats" to sleep on.  At that point, my eyes were crossing and I had to stop reading.

So the upshot of it all: go barefoot if you want.  It does feel nice, although we do have shoes for a reason, which you'll discover the next time you're "grounding yourself" in your front yard and you step on a thistle.  As far as the rest of her claim, it seems to be unadulterated fiction.

Just like her "free radical positive electrons."