A sun with no size

When I was in college, the original series Cosmos, hosted by Cornell University astrophysicist Carl Sagan, aired for the first time.

I was absolutely captivated.  I'd been an astronomy buff since middle school.  I was given my own telescope as a birthday present when I was thirteen, and spent many a happy evening in my parents' front yard trying to find the cool-looking astronomical objects I found on the star maps I collected obsessively.  (This is when I first fell in love with the Pleiades -- still my favorite naked-eye star group -- and when I found out that these were recently-created stars, almost fifty times younger than the Sun, I thought that was so cool.  It wasn't until I took an astronomy course in college that I learned how astronomers knew this.)

But when Cosmos came on, it took my interest to a whole new level.  For the time, the special effects and animations were stunning.  The soundtrack was nothing short of brilliant (in fact, it was my first introduction to the music of Dmitri Shostakovich, who has been one of my top three favorite composers ever since).  Sagan's writing and delivery were captivating; like many people who've seen it, if you read quotes from the scripts, you'll hear them in Sagan's unmistakable voice.  I'm not the only one who responded this way; the wildly talented rapper Greydon Square's song "Galaxy Rise" from his album The Mandelbrot Set is a tribute to Sagan and American physicist Michio Kaku.  Square himself majored in physics in college and includes concepts from science in a great many of his songs.

There were a couple of moments, though, that stand out in my memory as being jaw-dropping.  One was the breathtaking animation of colliding galaxies -- all generated from then cutting-edge computer models -- in episode ten, "The Edge of Forever."  But one passage from episode nine, "The Lives of the Stars," impressed me so much that now, forty-two years later, I can very nearly quote it from memory:

There are three ways that stars die.  Their fates are predestined; everything depends on their initial mass.  A typical star with a mass like the Sun will one day continue its collapse until its density becomes very high, and then the contraction is stopped by the mutual repulsion of the overcrowded electrons in its interior.  A collapsing star twice as massive as the Sun isn't stopped by the electron pressure.  It goes on falling in on itself until nuclear forces come into play, and they hold up the weight of the star.  But a collapsing star three times as massive as the sun isn't stopped even by nuclear forces.  There's no force known that can withstand this enormous compression.  And such a star has an astonishing destiny: it continues to collapse until it vanishes utterly.

Each star is described by the force that holds it up against gravity.  A star that's supported by its gas pressure is a normal, run-of-the-mill star like the Sun.  A collapsed star that's held up by electron forces is called a white dwarf.  It's a sun shrunk to the size of the Earth.  A collapsed star supported by nuclear forces is called a neutron star.  It's a sun shrunk to the size of a city. And a star so massive that in its final collapse it disappears altogether is called a black hole.

It's a sun with no size at all.

I can't imagine hearing the last line and not being a little goggle-eyed.

Since Sagan's time, we've learned a great deal more, but by and large, his series still holds up pretty well.  In fact, three years ago astronomers captured the first-ever photograph of a black hole (visible because of the x-ray emission of matter spiraling down toward its event horizon).  And just last week a paper appeared in Physical Review Letters about an event of cataclysmic proportions -- the collision of two black holes.

The collision was detected because of gravitational waves -- ripples in the fabric of spacetime that propagate outward from accelerating masses at the speed of light.  Most gravitational waves are tiny, so it takes huge masses moving really fast to detect them here on Earth; but these were so enormous that they were picked up by two separate detectors (LIGO and Virgo) from 1.2 billion light years away.  Here's artist Aurore Simonnet's conception of what this would have looked like from (much) closer:

It's hard to describe this event without lapsing into superlatives.  One of the most amazing things about it is that apparently, there was an asymmetry in the production of gravitational waves, and that gave a kick to the (larger) black hole produced once they coalesced, because of Newton's Third Law.

Well, "kick" doesn't begin to describe it.  The recoil from this particular gun left the bullet traveling at 0.5% of the speed of light -- about 1,500 kilometers per second.  Imagine the force it would require to propel a mass that large at that speed.  (Remember that Sagan said black holes only form from stars with a minimum mass of three times that of the Sun.  Minimum.  And this was two of them put together.)

So that's our mind-blowing news from astronomy for today.  Even though I have (on some level) known about this stuff for more than four decades, I still can't help being left in awe by the grandeur and beauty of the universe we live in, and by what we continue to add to our body of knowledge about how it works.

I think Carl Sagan would be delighted.

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In the dark

 "Okay, that's cool, but what the hell am I looking at?"

That was my reaction to a press release last week from the Harvard-Smithsonian Center for Astrophysics about a new study of the distribution of dark matter in the universe.  Turns out it's not uniform, which is what I'd have expected given that it apparently doesn't interact with anything except via gravitation (although I hardly need to point out that my opinion on the matter counts for next to nothing because I'm not a physicist).  It exists in filaments and haloes, where the majority of galaxies are concentrated.  Here's one of the images they generated:

I know you can't read much into appearances, but I was immediately struck by how much this image, especially the right-hand part, looks like a neural net.  (I'm just waiting for the woo-woos to latch onto this and claim that this proves the universe is a giant brain.)

"Amongst the things we’ve learned from our simulations is that gravity leads to dark matter particles 'clumping' in overly dense regions of the universe, settling into what’s known as dark matter haloes," said study lead author Sownak Bose.  "These can essentially be thought of as big wells of gravity filled with dark matter particles.  We think that every galaxy in the cosmos is surrounded by an extended distribution of dark matter, which outweighs the luminous material of the galaxy by between a factor of 10-100, depending on the type of galaxy.  Because this dark matter surrounds every galaxy in all directions, we refer to it as a 'halo.'"

So this could be a partial explanation for structures like the Boötes Void, a region of space so empty that (in the words of astronomer Greg Aldering) if the Milky Way was at the center of it, we wouldn't have known about the existence of other galaxies until the 1960s.  It's about 236,000 cubic megaparsecs -- equivalent to a cube 61 trillion parsecs on each side -- and, as of this writing, seems to contain only sixty galaxies.

That, my friends, is a whole lot of nothing.

The distribution of matter in space is clumpy and irregular.  Whether this drives the distribution of dark matter, or it's the other way around (the distribution of dark matter drives the arrangement of ordinary matter in the cosmos) is unknown.

Because that's the trouble, here, to go back to my initial question.  We've got some wonderful pictures of dark matter haloes and filaments, but what the hell is it?  I know the physicists have been working on this question ever since astronomer Vera Rubin demonstrated its existence back in the 1990s, but for cryin' in the sink, it makes up 83% of the mass of the universe, and we still don't have a good idea of what it's made of or how it interacts (again, other than its gravitational signature, which is how it was detected in the first place).

But what dark matter actually is still lies in the realm of speculation.  "Ground-based telescopes like the Very Energetic Radiation Imaging Telescope Array System (VERITAS) can be used for this purpose [detecting dark matter], too." said Jie Wang, who co-authored the study.  "And, pointing telescopes at galaxies other than our own could also help, as this radiation should be produced in all dark matter haloes.  With the knowledge from our simulation, we can evaluate many different tools to detect haloes—gamma-ray, gravitational lensing, dynamics.  These methods are all promising in the work to shed light on the nature of dark matter particles."

So the upshot is there's a network of invisible stuff spreading through the entire universe, perhaps organizing the distribution of ordinary matter, but for sure surrounding and penetrating everything there is.  Without interacting with it in any way other than gravity (as far as we can tell).

Which is a hell of a mystery, isn't it?

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This week's Skeptophilia book-of-the-week is about one of the most terrifying viruses known to man: rabies.

In Rabid: A Cultural History of the World's Most Diabolical Virus, by Bill Wasik and Monica Murphy, we learn about the history and biology of this tiny bit of protein and DNA that has, once you develop symptoms, a nearly 100% mortality rate.  Not only that, but it is unusual amongst pathogens at having extremely low host specificity.  It's transmissible to most mammal species, and there have been cases of humans contracting rabies not from one of the "big five" -- raccoons, foxes, skunks, bats, and dogs -- but from animals like deer.

Rabid goes through not only what medical science has to say about the virus and the disease it causes, but its history, including the possibility that it gave rise to the legends of lycanthropy and werewolves.  It's a fascinating read.

Even though it'll make you a little more wary of wildlife.

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

Fair and balanced nonsense

I suppose by now that I should have expected something like this, but still, I was surprised when I heard that the creationists are now asking for airtime for their views, so that the media can be more "fair and balanced."

It's another jab at Neil deGrasse Tyson and Cosmos again, of course.  Tyson is, as I mentioned in a recent post, unabashedly supportive of the evolutionary model, as well he should be; if you accept the methods of science at all, the amount of evidence in favor of evolution (and the complete dearth of evidence for any other competing model) leaves you little room to escape.  But that doesn't stop people from disbelieving, and it certainly didn't stop folks like Ken Ham from squalling like mad when Tyson called creationists simply "wrong."

What I didn't expect, though, was that the creationists were going to turn things around and demand that they have equal air time for their views, in the interest of fairness.

The idea jumped into public media a couple of days ago when Danny Faulkner of Answers In Genesis and the Creation Museum appeared on The Janet Mefferd Show.  Mefferd opened the topic up by asking if Cosmos will "ever give a creationist any time," and Faulkner answered that "creationists aren’t even on the radar screen for them, they wouldn’t even consider us plausible at all."

Mefferd said in response that Tyson and the writers of Cosmos weren't playing fair.  "Boy, but when you have so many scientists who simply do not accept Darwinian evolution," she said, "it seems to me that that might be something to throw in there, you know, the old, 'some scientists say this, others disagree and think this,' but that’s not even allowed."  (To listen to an audio recording of the interview, go here.)

There are two problems, of increasing seriousness, with this statement.

First, would you care to name for me the "so many scientists" who do not accept evolution?  There might be a few non-biologists, perhaps.  Amongst biologists, I think you'd be hard pressed to find more than one or two serious doubters -- and I would argue that even those, if they indeed exist, inhabit some sort of fringe-y twilight zone of biological research.  I.e.: I suspect they're cranks, not serious researchers.  At this point in the game, a biologist doubting evolution would be a little like a chemist doubting the periodic table.

A second, and more troubling problem, is that Mefferd and Faulkner think science needs to be "fair."  Wherever did they get that idea?

Now, don't get me wrong; in many circumstances, fairness is a good thing.  I try to deal with my students fairly; I expect to be treated fairly in business; I expect politicians to engage in fair dealings.  In any kind of human social interactions, fairness forms a good base guideline for behavior.

But science... science isn't fair at all.

Why not?  Well, partly it's because the universe isn't fair either.  There is absolutely no reason why the universe has to behave in such a way as to make me happy.  On a simplistic level, I would love it if magic was possible, if there was life after death, if there were friendly aliens who paid us visits periodically (I'm thinking of the wonderful final scene in Star Trek: First Contact).  Hell, while I'm wishing, I wish I could fly.  But there is no reason to believe that just because I'd like something to be a certain way, that the universe must conform to my wishes.  And more to the point, if science finds out different -- e.g., if controlled studies show that my magic wand can not make my dog levitate -- then science isn't being unfair to me.

It's simply showing me how things are.

[image courtesy of photographer Des Colhoun and the Wikimedia Commons]

So in a way, I misstated the fact; it's not that science isn't fair, it's that it's kind of above considerations of fairness and unfairness.  It deals with what is demonstrably real, and leads our understanding where the evidence takes us.  If that's a different place than where we'd hoped to be, well... too bad, so sad.

And there is no reason in the world that any responsible media outlet should feel compelled to give the creationists equal time, any more than I should be encouraged to teach the Theory of Magical Dog Levitation in my science classes.  Creationism and Magical Dog Levitation are both supported by equal amounts of hard evidence (i.e., zero), and therefore to give time to either one wouldn't be fair, it would be idiotic.

But of course, the media is not controlled by what is scientifically sound, it's controlled by what gets viewers (and therefore, what gets sponsors and makes money).  Witness what has happened in the past few years to the This Really Has Nothing To Do With History Channel.  So I wouldn't be at all surprised if we see a series coming down the line called The Six Days of Creation.

At least I can feel some joy in the knowledge that whoever they'd get to narrate it wouldn't be nearly as badass as Neil deGrasse Tyson, because he seems to have cornered the market on badassery these days.

Big brawl over the Big Bang

So apparently, there are a number of people who have their knickers in a twist over the new Cosmos.

The young-Earthers are, predictably, upset with host Neil deGrasse Tyson's repeated mentioning of evolution.  Dan Dewitt, writing for Baptist Press, was perturbed by the whole message, but showed evidence of a severe irony deficiency when he stated that Tyson's Cosmos was "regurgitating... old myths... and proposing theories that have zero physical evidence."

Then we have the climate change deniers, who were torqued by a mention of anthropogenic climate change in each of the first two episodes, with more likely to come.  Jeff Meyer, writing at Brent Bozell's conservative outlet Media Research Center, said, "...deGrasse Tyson chose to take a cheap shot at religious people and claim they don't believe in science, i.e. liberal causes like global warming."

Well, yeah.  Because, largely, they don't.  And climate change is hardly a "liberal cause," unless you accept the idea that in Stephen Colbert's words, "reality has a well-known liberal bias."

Then, we have the people who object to the idea of the Big Bang, which was more or less the topic of the entire first episode.  Elizabeth Mitchell, writing over at the frequently-quoted site Answers in Genesis, had the following to say:

The “observational evidence” [for the Big Bang] to which Tyson refers is not, however, observations that confirm big bang cosmology but interpretations of scientific data that interpret observations within a big bang model of origins. The big bang model is unable to explain many scientific observations, but this is of course not mentioned.

What makes Mitchell's comment even more ludicrous than it would be if read alone is how it appears in juxtaposition with the news from two days ago, in which we find that scientists working in Antarctica have conclusively proven the existence of gravitational waves -- remnants of quantum fluctuations that were created in the first 0.00000000000000000000000000000001 seconds of the universe's existence.  (For those of you who don't want to count, that's 31 zeroes; if you're conversant in scientific notation, it's 10^-32 seconds.)

This map represents nine years' worth of data from the Wilkinson Microwave Anisotropy Probe, which shows minor temperature fluctuations registering in the microwave region of the spectrum -- fluctuations caused by inflation that occurred 13.7 billion years ago.  [image courtesy of NASA, the WMAP team, and the Wikimedia Commons]

I'm sure Mitchell would shriek about "observational" versus "historical" science, and how I wasn't there during the Big Bang to observe what the universe was doing (and given what was happening at the time, I'm damn glad I wasn't).  But keep in mind that the gravitational waves that have been observed were predicted years ago by Andrei Linde, one of the chief architects of inflation theory -- a model of Big Bang cosmology that has now been given a significant leg up over other theories of the early universe.

The synchronicity of Mitchell's snarky little commentary, followed by the triumphal announcement of Linde's vindication, makes me think that if there is a god, he's got quite a wicked sense of humor.  It puts me in mind of a quote from Voltaire: "God is a comedian playing to an audience that is afraid to laugh." And if you want to see something uplifting to counterbalance Mitchell's ignorant criticism, watch this video of Linde being told by physicist Chao-Lin Kuo that the existence of gravitational waves had been proven.  It'll make you smile.

But back to Cosmos.  I do find it heartening that Tyson isn't pussyfooting around on these subjects.  Sagan, partly driven by the fact that the original series was filmed in the 1970s, had to be a little more circumspect about what he said, a little more diplomatic.  Myself, I think Tyson is taking the right approach.  I'm sorry if you don't "believe" in the Big Bang, in evolution, in climate change.  You're wrong.  You can continue to claim that the evidence doesn't exist, or is inconclusive or equivocal.  You're wrong about that, too.  If you'd like to remain ignorant of the reality, that's entirely your prerogative, but you can no longer expect the rest of us to go along with you out of some odd notion that ideas, however ridiculous they are, deserve respect.

Time to play hardball, people.