Frank on Science!: Dark Matter

If you wonder how Science! can know facts about distant objects likes black holes and quasars, it’s that we come at it from a number of different angles and make sure it all adds up. For instance, if we want to check the mass of a distant galaxy, we estimate it based on its brightness versus known masses of stars. Then we estimate the mass of the galaxy based on the galaxy rotation curve (orbital velocity of stars versus distance from the center of the galaxy). And those two should match.

Except they don’t. In fact, it’s not even close. Like we get a number around twenty times bigger looking at the galaxy’s rotation. So basically, the matter we can see only accounts for around 5% of the universe, and the rest is… well… invisible.

Yeah, I know what you laymen are thinking: “Silly scientists! You just forgot to carry to one and are making a big deal about it! It’s like me thinking there are invisible cheeseburgers because the amount of money in my register didn’t match sales at the end of my shift at Wendy’s.”

No, we’ve like checked this a million times. We’d love to say it’s just a math error, but the only conclusion we can come to is we can’t find most of the universe. This “dark matter” (transparent, really) is most of existence and we don’t have a friggin’ clue where it is. And most of it is nonbaryonic, which means it contains no atoms and does not interact with normal matter.

No! That does not mean it’s imaginary! It’s not Snuffaluffagus matter. It’s just invisible and can’t be felt, but it is totally there. Just look at galaxy rotation curves or galaxies’ velocity dispersion or apply the viral theorem; we’re missing a lot of mass, and it is very frustrating. I know Science! will make it clear eventually, but it’s hard to just push out of our minds right now.

Anyway, if you see any mass that’s unaccounted for, please go to your nearest Sciencetorium and report it. And, as I have to keep explaining to you laymen, be as descriptive as possible. Just saying, “It was big!” doesn’t help us.

Science!

50 Comments

  1. If it does not interact with normal matter than it can’t possibly be of any use … so then the purpose of the investigation into dark matter is to provide scientists with a reason to ask for grant money.

    [Yes, what possible reason could people want to have answers to unanswered questions than more grant money. We figure out what it is, then maybe we find a use for it.

    Science!]

  2. “The Dark Matter Dragon In My Garage” with apologies to Carl Sagan

    “A fire-breathing dragon lives in my garage.”

    Suppose I seriously make such an assertion to you. Surely you’d want to check it out, see for yourself. There have been innumerable stories of dragons over the centuries, but no real evidence. What an opportunity!

    “Show me”, you say, and I lead you to my garage. You look inside and see a ladder, empty paint cans, an old tricycle – but no dragon

    “Where’s the dragon”, you ask.

    “Oh, she’s right here”, I reply, waving vaguely. “I neglected to mention that she’s an invisible dragon”.

    You propose spreading flour on the floor of the garage to capture the dragon’s footprints. “Good idea”, I say, “but this dragon floats in the air”. Then you’ll use an infrared sensor to detect the invisible fire. “Good idea, but the invisible fire is also heatless”, I say. You’ll spray-paint the dragon and make her visible. “Good idea, except she’s an incorporeal (bodyless) dragon and the paint won’t stick!”

    And so on. I counter every physical test you propose with a special explanation of why it won’t work.

    Now what is the difference between an invisible, incorporeal, floating dragon who spits heatless fire and no dragon at all? If there’s no way to disprove my contention, no conceivable experiment that would count against it, what does it mean to say that my dragon exists? You’re inability to invalidate my hypothesis is not at all the same thing as proving it true. Claims that cannot be tested, assertions immune to disproof are veridically worthless, whatever value they may have in inspiring us or in exciting our sense of wonder. What I’m asking you to do comes down to believing, in the absence of evidence, on my say-so.

    But then I say, “Well, that’s because the dragon is made of Dark Matter.” And then you walk away satisfied that there really is a dragon in my garage, because apparently, scientists nowadays will believe anything, as long as it’s told to them by other scientists. Witness Climategate.”

    [These are not imaginary dragons! These are reproducible calculations to show there is missing mass! Gah! -Science! Ed.]

  3. Perhaps it is all the craptacular TV we have been beaming out into space for the last 60 years. If ‘perfect strangers’ isn’t weighing down the universe like a christmas fruitcake I don’t know what is.

    Also perhaps it is angels. There must be alot of them and each one has a lot of stuff.

  4. I figure it’s from one of two things, either scientists have no idea what “known” stars mass so they’re basically multiplying nonsense numbers together and not finding anything or they keep doing our galaxy in US units and other galaxies in SI units.

  5. Alternatively, since we have no idea how gravity works, we’re not calculating what we think we are.
    Dark Matter is just a sciency way to say, “Magic elves”.
    Which are the ones you said make gravity work as I recall.

    Hmmmmmm.

    [Based on our current understanding, “magic elves” is still a valid hypothesis. -Science! Ed.]

  6. One thing we can learn from Climategate is that Science! doesn’t like heretics, especially those who come to the game armed with facts, evidence, and the pocketbook set of physical law definitions capable of backing up their heresies. That is NO FUN. The heretical rubes simply don’t get it – when Science! comes to the game, the point is to play WITH the facts, not simply use them as a basis. And (insert deity of choice or “Present” here) help the unwashed non-degreed B+ muggles who want to have a voice in the matter.

    Anyways, not that it is very humorous… or even humorous at all, but there actually is a real answer as to why we can’t detect “Dark Matter” – there isn’t any. We’ve come to the “Dark Matter” conclusion, having “checked this a million times”, by starting on an unsound premise.

    You want a firm foundation? Remember your Electrical Engineering and check out the “Electric Universe” theory (which due to overwhelming overlap is often – and quite justly – confused with “Plasma Cosmology”). One thing you’ll find right off the bat is that the proponents are considered heretics, quacks, loons, and hacks by the Science! orthodoxy. But the EU crowd actually follows the science and refrains from creating wholesale sci-fi scenarios (and bad sci-fi at that) when examining things like slight fluctuations in a star’s spectrum. To Science! that’s no fun, and a real looser when trying to get a grant proposal going…

  7. SCIENCE ! is just an excuse to use lots and lots of polysyllabic latinate words to impress coeds.
    you know…words like, Dark and Matter and Snuffaluffagus.
    Remember if you stare to long into the dark matter, the dark matter will stare into you.
    seriously, -what-went bang? (as in big)

  8. Frank said: “This “dark matter” (transparent, really) is most of existence and we don’t have a friggin’ clue where it is. And most of it is nonbaryonic, which means it contains no atoms and does not interact with normal matter.”

    Well, that’s the perfect explanation for liberal brain mass, i.e.: see Obama’s first year:

  9. Personally, I think it’s more likely that the underlying assumptions behind the calculations are wrong. “Dark Matter” logic doesn’t hold up in any other field.

    Detective: All the evidence and logic indicate that there was no-one in the room with the victim when he was murdered. Therefore, he was murdered by an invisible, incorporeal man who leave no evidence behind!

    Engineer: All my calculations show that this building should not be standing. Since it is still standing, therefore there must be some sort of invisible, incorporeal support beams holding it up!

    Conspiracy Nut: All of my calculations show that there is no way an airplane could bring down the Twin Towers. Therefore, there must have been some really, really sneaky government agents, who no-one saw, who planted explosives in the buildings, which no-one ever found evidence for!

    The only reason anyone believes in Dark Matter is because it’s all really, really far away, and we have to take Scientists’! word for it.

  10. HWUU- Carl Sagan maintained that all those years of craptasic Tv being beamed into space was proof enough that we are alone in the universe. Surely, by now, the Vulcans would have stopped by and told us to knock it off!

  11. Frank, please follow this up with a piece on Dark Energy, aka the Cosmological Constant hokey-pokey. Great Feynman’s Ghost but we never test our theories these days!

    “If she weighs like a duck, she must be a witch!”

  12. Hey, has there been any improvement in measuring the intrinsic brightness of a galaxy? I got bored and stopped reading the literature back in the late 70s when we used variable stars inside the galaxies…* To use such a yardstick, you must assume that a variable star with a certain period always has a certain brightness, so we can infer the distance…

    I think that intrinsic brightness measurement is like important and stuff, because it determines the first part of your non-equating equation, the mass of the galaxy based on brightness based on distance. Hey?

    *Okay, I never read the literature, I only ever watched reruns of Project Universe on PBS

  13. How do they measure the speed of rotation of a galaxy again?
    Is there one old dude in the observatory with a stop-watch waiting for a mile marker to go past?
    Maybe what’s holding the galaxies togeather is static-cling?

  14. For instance, if we want to check the mass of a distant galaxy, we estimate it based on its brightness versus known masses of stars.

    At least that’s what we want to think we are doing. Of course, what we are really doing is making a comparison to the theoretical masses of stars.

  15. Science! Is still the best way we can test and verify what is ‘real’. I won’t dis the scientific method.

    But I agree things like dark matter and string theory are a long way from being veritable because they are a bit much of theories based upon theories, that probably for a long while to come, will not be verifiable… for instance, until we can get a probe a bit farther out to see another star (solar) system and how it functions, or how gravity really works. We are as one scientist said, (I think Michao Kaku? (spelling?) mkaku.org ) We’re 3 dimensional creatures attempting to possibly be describing an 11, 12 or even more dimensional universe, like Koi making assertions about objects outside their pond.

    We’ve got a long way to go.

  16. I’d say “Dark Matter” explained the liberal brain but there head is full of a different matter. I’ll give you a hint it smells and it’s what my neighbor’s dog did in my front yard.

  17. First, the Dark Elf’s name is Eol. Silmarillion!

    Next, it’s okay if we can’t find most of the universe. It knows where to find us, if it needs us; but it is a very benevolent sort of universe and mostly just lets us alone in our local playpen, where we can dream of Science! and Snuffaluffagus matter and “dark energy”/”dark matter”/”Cinderella universes” and other such fun nonsense.

    Finally, this may just all mean that we’re playing the game correctly, because as the eminent laffologists Pratchett and Gaiman noted in their field report Good Omens, “God does not play dice with the universe; He plays an ineffable game of His own devising, which might be compared, from the perspective of the players, (ie everybody), to being involved in an obscure and complex version of poker in a pitch-dark room, with blank cards, for infinite stakes, with a Dealer who won’t tell you the rules, and who smiles all the time.”

  18. While elves is a valid hypothesis, you can’t hypothesize that the elves are magical, because magical = non-scientific, so there is no scientific method for determining whether something is magical. You can only say in religion class that some people believe the elves are magical.

  19. @shiggz Maybe they do; dunno. Maybe more conservatives (and others) should write..

    I miss TP; hope he’s doing well, wherever he’s at just now. NG is writing children’s books, and doing quite well, I guess. If only I had more time, I’d read them. Anyway, Good Omens is where I first heard of G. K. Chesterton, and that’s good. That’s very good.

    A trailing meteor on the Downs he rides above the rotting towns,
    The Horseman of Apocalypse, the Rider of the Shires.
    For London Bridge is broken down, broken down, broken down;
    Blow the horn of Huntington from Scotland to the sea —
    …Only flash of thunder-light, a flying dream of thunder-light,
    Had shown under the shattered sky a people that were free.

    — From “The Old Song,” by Chesterton

  20. 4of7, actually rotation is pretty accurately measured by the blue-shift of light from stars rotating toward us, compared to the red-shift of those rotating away from us. Course, everything is red-shifted due to expansion of the universe.

    Thank you! I’ll give you my shipping address and garter size for my Major Award.

  21. @Capitalist_B, I don’t think that comes into the rotation measurement, if you’re just measuring relative red shifts. I mean, the spectrum of one star on one side vs. the spectrum of a similar star on the other side. Perhaps I’m missing something?

    I’m not biased against the Dark Matter idea, but to my earlier point I’m genuinely curious to know if we have better methods nowadays to measure the intrinsic brightness of a distant galaxy. It seems to me a lot is riding on that measurement…

  22. @Arnie: well, I have something against dark matter! I’d like to term it “graviston” so that it sounds more like “phlogiston.”. Rotations is a good answer, but gravity is still inertia is still gravity. There’s something very fundamental about General Relativity that we’re missing here, and it’s staring us straight in the face.

  23. Always helps to remember that mathematics and time are HUMAN constructs.
    Three dimensional beings contemplating a multi-dimensional universe , that’s a tough row to hoe.
    For the time being Elves are a lot more appealing then mini black holes. even if they keep hiding my car-keys

  24. #43 – Arnie,
    Thanks!
    I figured it had something to do with that red shift/blue shift deal, because I know we haven’t be looking out into space long enough to see a galaxy make one full revolution.
    (But wouldn’t That be cool?)

    “What? You can actually See it move?!”
    “Yeah. Do You want to try explain it?”
    “Er… Let’s agree to never look in that direction again, OK?”
    “I didn’t see a thing!”

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