Episode 150 - Is Dark Matter Liberal Pseudoscience?
Recap: Moving away from the Earth-centric episodes since The Return of the podcast, this epsidoe addresses the concept of dark matter and claims that it is pseudoscience (and liberal pseudoscience at that!). Throughout the episode, we explore the history of the concept, how it arose, and why it arose, and then some alternative explanations. I make the case that it is not pseudoscience at all, but real, genuine, Grade-A science.
- References and Resources
- Logical Fallacies / Critical Thinking Terms addressed in this episode: Ad hominem, God of the Gaps, and Occam's Razor
- Relevant Posts on my "Exposing PseudoAstronomy" Blog
Claim: This is perhaps a bit of an odd claim, especially for an episode as psychologically significant as 150, but I wanted to get away from the last couple which were very Earth-centric and, well, dark matter is about as far as you can get. So, dark matter ... is it liberal pseudoscience? That's the claim made by a website that I don't think I've used before on this podcast, and that is Conservapedia, which bills itself as "The Trustworthy Encyclopedia." On their page about Dark Matter, which I will discuss in more depth in a few minutes, if you scroll all the way to the bottom, it has a table titled, "Theory of Relativity." Underneath it are the topics, "Theories," "Geometry," "Controversy and disproofs," "Liberal pseudoscience," and "See also." Listed next to the liberal pseudosciece are Black holes, Dark Matter, Moral relativism, and Wormholes. I think just from the categorization of these, you can get an idea of where this might be headed, but let's delve in a bit more. As always, the purpose of this show is not to just point out something crazy, but to use it as an excuse to learn about science.
But, that doesn't mean we can't talk about the crazy. Conservapedia is just that. The site was founded by Andrew Schlafly, son of the late Phyllis Schlafly, who was an icon in the social conservative movement in the United States. Phyllis made her name really in the 1970s as a counter to the feminist movement, organizing widespread opposition to the Equal Rights Amendment. She remained a figurehead of those conservative ideas throughout her life, and it was in that environment that her childrens' views were shaped.
Andrew Schlafly was no exception, and he founded Conservapedia in 2006 as a counter to what he and others on what I think I can fairly term the extreme social conservative movement viewed as too much "liberal bias" in Wikipedia.
I've been able to get this far without mentioning religion, but that's as far as I can get. Conservapedia itself has many pages which are practically clones of CreationWiki, an online collaborative encyclopedia which, as the name suggests, is written by creationists, specifically, usually, of the young-Earth viewpoint.
Therefore, it is within these two viewpoints -- extreme conservativism and young-Earth creationism - that Conservapedia lies, and the topic du jour of this episode, is dark matter liberal pseudoscience.
Removing the Political Label
With that background out of the way, and I think a very "restrained" description of Conservapedia, we can begin to answer the question. And, I'm going to be frank here and just say off the bat I'm not going to address the idea of liberal versus conservative pseudoscience. Science is science, and if I can show that dark matter is not pseudoscience but rather science, then it has no political component. Science is science, it's not liberal or conservative.
The Astronomy Problem in the 1990s
To then make the case of whether the idea of dark matter is science or pseudoscience, we have to go back to the 1990s, a fun decade that had competing boybands and a budget surplus. Y2K was going to kill all technology, and Donald Trump was just a real estate developer and on his first wife.
It was the 1990s that saw a culmination of numerous, independent lines of evidence that what we thought we understood about the nature of the universe was wrong.
To understand what I mean by that, we need to go back to the Roaring Twenties, when Jacobus Kapteyn proposed in 1922 that there might be material in the universe that we couldn't see. This was supported by Jan Oort in 1932. Both astronomers were studying the motions of stars. What they saw was the overall, bulk motions of the stars were moving faster than they should.
They had looked at all the light from visible objects, calculated how fast stars should be moving, and what they really observed for the stars' motions was too fast. Therefore, both independently proposed that there might be material that was unseen that was causing the stars to move as fast as they were. I'll quickly note that Oort's specific measurements were later shown to be wrong.
But, I now need to explain why the proposed answer to the observation was more, unseen mass. To do that, we go back to one of the main sponsors of the podcast, Johannes Kepler. Kepler's Third Law of motion tells us how long it should take for an object to orbit something given the distance from the object and the mass of the two objects. If you know the distance and the length of time of the orbit, you can very easily calculate what that orbital speed should be.
And so, using Kepler's laws, if you add up the mass of the objects emitting light, and you observe a star at a certain distance from the center of a galaxy, then you know how long it should take that star to orbit around the center of the galaxy, and you can calculate what the speed should be.
We can use pretty straightforward methods to observe how fast stars are moving towards or away from us - basically, the Doppler Shift. If an object is moving towards us, the light will be shifted to shorter wavelenghts because they're compressed, so they'll look bluer than they really are. Moving away from us is the opposite. So we can get at the real speed of the stars, compare that with the theoretical speed, and dee if they match.
If they don't match, really, that can only mean three things: (1) Either the measurements are wrong, (2) the mass is wrong, or (3) our understanding of gravity, which is the theoretical underpinnings that support Kepler's Laws, is wrong.
So, as a quick mid-section recap: Nearly a century ago, we used straightforward measurements to compare the speeds of stars in other galaxies with predictions. The stars moved too fast. But, option 1 - bad measurements - were the reason for Jan Oort's.
However, these kinds of measurements persisted. Fritz Zwicky saw the same thing with galaxy clusters in 1933 and made the first formal proposition about the existence of the idea of "dark matter," or "dunkle Materie," an unseen mass that provided the extra gravity to make stars move as fast as they were seen to move (and yes, I realize I haven't defined dark matter yet -- I'm getting there). His observations suggested that the large galaxy cluster called the Coma cluster required 400 times more mass than was available in all the stars and all the nebulae.
Same thing with the Andromeda galaxy in 1939, other galaxies in the 1960s and '70s, and many other observations after that.
What changed in the 1990s was that a second, independent line of evidence was made available for the existence of some unseen material. The Cosmic Microwave Background radiation, which had been discovered in the 1960s and earned its discoverers a Nobel Prize in Physics, is the leftover radiation from when the universe first became transparent to light, about 375,000 years after the Big Bang.
The COBE satellite, or Cosmic Background Explorer, returned its data in 1992 and became the first instrument to measure little, teeny tiny variations in the nearly perfect temperature. These fluctuations are at a level of 0.01%.
What's important about these fluctuations is that their size on the sky is dependent on a few very fundamental things about our universe, and one of them is whether there is dark matter and if there is, how much of it. By adjusting these parameters, you can get different predictions for how the Cosmic Microwave Background radiation should look, and the absolute best fit comes with a universe where the amount of dark matter is a little more than five times as much as normal matter.
And so, at the end of this history lesson, we have the following situation:
For hundreds of years, based on empirical relationships from Kepler and the theoretical underpinnings of gravity from Newton, we know how fast stuff should move around other stuff in space.
For one hundred years, we've measured that the objects at the edges move too fast based on adding up all the material that can be seen and estimated based on other methods. For observational astronomers, that's the biggest and most obvious clue that there is some missing matter. OR, gravity acts differently on the largest scales in the universe.
Then came precise measurements of the Cosmic Microwave Background radiation which showed that normal matter only makes up about 4% of the mass-energy of the universe, and another 21% is made of matter which we can't see. For theoreticians, this is some of the best evidence for dark matter.
There are several other lines of evidence for dark matter, but those are really the main two and easiest to explain. I have also left out a huge number of details in the discussion here, but if you're interested in learning more, Wikipedia, with all its alleged liberal bias, has a lot of detail of the observational evidence for dark matter that I'll link to in the shownotes.
MOND: MOdified Newtonian Dynamics
I would be remiss at this point if I did not mention MOND, or MOdified Newtonian Dynamics. After all, I said there were three possible reasons for the galaxy rotation curves, and after experimental error was ruled out, just two: Either there's more mass, or there may be a missing component to our equations for gravity which only become apparent at giant scales.
MOND is that component. Hence the name, it modifies Newtonian dynamics, or Newton's theory of gravity.
Most cosmologists though, consider MOND to be less likely than dark matter. The cosmic microwave background especially fits the predictions for dark matter but didn't fit MOND, though the person who came up with MOND claims he can modify it to fit the background radiation measurements.
Suffice to say for THIS podcast, MOND is now generally considered to be a fringe idea and very, very few of the people who study cosmology consider it seriously anymore. BUT, whether is is the reality of the universe or dark matter is, what I've set out to do is to make the case that the idea of dark matter is not pseudoscience. And, just because some idea may later be shown to be wrong does not mean that it is pseudoscience so long as the ideas behind it were sound at the time.
What Is Dark Matter?
So, let's get back to dark matter. I've made the case for why people think there is something extra there, but now I need to tell you what dark matter really is. We have no idea. Well, we have ideas, but we haven't been able to verify anything yet, though we've ruled things out over the last 20 or so years.
The core idea behind the "stuff" is that it's matter - as in material like atoms as opposed to energy like photons of light - and it's "dark" in that we literally cannot see it at all in any wavelength we've looked at with light. This is as opposed to ordinary matter, which does interact with light.
The only thing that dark matter seems to interact with is gravity.
So, what could it be?
If you go back to episode 69, I discussed the solar neutrino problem, something that was solved in 2001 that showed that neutrinos, particles that can pass through Earth without a second thought, have mass. This was incredibly important because it had been thought before that they were massless. But, from examining the large-scale structure of the universe and details of the cosmic microwave background, neutrinos only make up a very small portion of the mass-energy of the universe, and so they can't be what dark matter is.
We also thought for a time that it could be something like a large population of black holes, or other massive objects that didn't emit light called "MACHOs" for "massive compact halo object." On the other end, some theoreticians have proposed WIMPs may make up dark matter, where WIMP stands for "weakly interacting massive particle."
But, we've really looked, and there are multiple lines of evidence that say we're looking for something that really is unlike any kind of matter we're familiar with, where even MACHOs and WIMPs would still be new to discover, but they can still interact with light whereas dark matter does not.
One way we've ruled these out as dark matter is through the cosmic microwave background which I've already mentioned. We can really only reproduce theoretically what we see observationally if there's a large component of the universe which only interacts with light through gravity, and not through absorption and/or emission and/or reflection.
Another way is that we've looked for MACHOs. Even if they're dark, their gravity will bend the light of distant objects through a process called "gravitational lensing." If a sizable component of dark matter were MACHOs, then we should see gravitational lensing at a much, MUCH larger rate than we do. And on the other end, we've looked for WIMPs through numerous particle detector experiments and still haven't found anything.
So, what we're left with is ideas, possible methods to test some of them, and many, many things that have been ruled out.
Is that science? The process of evidence for something and then lots of elimination of different possible components of it? I would argue yes.
I would argue that the process here follows the process of science rather than pseudoscience, it's withstood many attempts to falsify or explain it through other means, and we keep coming back to the idea that the best explanation is still one where there's some weird form of matter that only interacts with the rest of the universe through gravity.
Alternative Science (fiction?) Explanations
That doesn't mean there aren't other potential explanations. I've already mentioned MOND.
Another possible explanation which I think would be really neat if there were ANY way to test it is that maybe there are extra dimensions to our universe, and gravity is the only fundamental force that can cross between them. That could explain why gravity is the weakest of the four known fundamental forces in the universe, because it's spread out over more dimensions. Then, the missing mass, or dark matter, would be in those other dimensions and therefore only visible through their interaction with gravity. So the movie "Interstellar" was correct.
Another possibility that's been proposed is that there are primordial "defects" in quantum mechanical fields. Those defects contain embedded energy and therefore have a gravitational component. This could actually be tested with a network of space-based atomic clocks, but a direct test has never been done. And if my explanation here seems even more wishy-washy than usual, that's because I am not a quantum physicist or mathematician and the idea of topology of quantum fields leaves me guessing at even the name, let alone delving any further.
But, with that said, and what I said before, I still think that I made a complete case for the idea of dark matter to be science and not pseudoscience. And with that made, I don't have to discuss liberal or conservative.
Young-Earth Creationist Viewpoint
After all this, I should give fair say to the young-Earth creationist viewpoint which inspired the Conservapedia article. From Creationwiki.org, which really is from what the Conservapedia article was copied-and-pasted in what Expat recently termed in a blog post about Mike Bara, "ctrl+c/ctrl+v scholarship," we have this:
"Creationism, of course, declares that any observed effect results from the creative action of God. In 2000, relying primarily on this theory, Don DeYoung, writing in the Creation Research Society Quarterly, concluded that the hand of God was responsible for holding rapidly spinning galaxies and larger systems together, despite the observed mass deficits. Most creation scientists, however, prefer to assume an economy of miracles.
The page then goes on to explain some ad hoc math that claims to give the right answer. The page also states that Don DeYoung "challenged the notion of dark matter as a fanciful concept with little justification. He pointed out that none of the conventional explanations popular AT THE TIME were satisfactory" (emphasis mine). As I already explained, though, real scientists have also ruled those out and continued to point to something that is not made of normal matter, which all of DeYoung's criticisms were about MACHOs and WIMPs.
The first half of Conservapedia's page is nearly exactly the same as the CreationWiki page, but it has an expanded section on criticisms of dark matter. Surprisingly though, it notes that DeYoung's "criticism has lost validity, however, as dark matter has been directly measured in filaments."
The Conservapedia article also discusses some of the controversies about dark matter's existence, though it fails to place them in proper context. The idea that there is a hidden component that's 21% of the universe is going to have detractors that bite at every stray thread there is, and without positive detection and identification of what dark matter may be - and there's no guarantee it's just one thing - there is going to be people who disagree with it. That's normal.
And, that's the way science works and is self-correcting. You have to have people nipping at the sides and constantly checking to see if things are on the up-and-up. Jan Oort's original measurements that supported dark matter were wrong. But later measurements showed that the phenomenon he described was correct.
Alternative explanations abound, but there are reasons why a new particle rather than modifying theoretical physics or what we think is the structure of the universe is preferable; one of those reasons is Occam's Razor, which suggests that the explanation that introduces the least amount of new information is most likely to be correct. But not necessarily.
Or, we could just go with GodDidIt, all one word. And if you want to use that miracle as your explanation, that's fine, but that doesn't mean you need to call real science politically motivated pseudoscience.
Provide Your Comments:
Comments to date: 2. Page 1 of 1. Average Rating:
Stuart R Lyons, CO, USA
11:57am on Thursday, October 27th, 2016
I'm not sure what happened with the audio. I think I accidentally was recording via my laptop's microphone instead of my normal one. I had to quit the recording software half-way through at which point I made sure it was from my normal microphone.
Daniel G.W. Warsaw, Poland
6:14pm on Tuesday, October 25th, 2016
Aside of audio being a bit weird (i.e. different than usual. New microphone or different room?), it was a really great episode. Kudos! :D