Thursday, April 19, 2012

Not Even A Little Bit!

Cal Tech physicist Sean Carroll has a post on his blog Cosmic Variance today, called "Jon Stewart Doesn’t Understand How Science Works Even a Little Bit" in which he takes Mr. Stewart to task for "misrepresenting science" in saying (in a 2010 interview with Marilynne Robinson) that a lot of it seems to rely on faith. Here is the offending passage:
I’ve always been fascinated that, the more you delve into science, the more it appears to rely on faith. You know, when they start to speak about the universe they say, well, actually, most of the universe is antimatter. Oh, really, where’s that? Well, you can’t see it. [Robinson: "Yes, exactly."] Well, where is it? It’s there. Can you measure it? We’re working on it. And it’s a very similar argument to someone who would say God created everything. Well where is he? He’s there. And I’m always struck by the similarity of the arguments at their core.
Carroll takes Stewart to have meant "dark matter," not antimatter, and he's upset that Jon doesn't appreciate the great deal of evidence that supports the existence of dark matter, which makes it a direct contrast to a hypothesis like Deism, for example. And indeed the evidence for dark matter is pretty good. There are gravitational fields in the Bullet Cluster, for example, where regular baryonic matter used to reside until it was pushed away by a collision with another cluster. Dark matter, being non-interactive with normal matter, would not be pushed away by the collision, which would explain the gravitational fields in the cluster's old location. Not a slam dunk, but compelling evidence all the same.

But what if Stewart wasn't referring to dark matter--what if he meant dark energy instead? The names are similar, and both dark matter and dark energy have an influence on cosmic gravitation, so it's easy for a layperson to confuse them.  Almost 3/4 of the universe is postulated to be "made of" dark energy, and we don't know anything about it, except that it "must" be there, to explain the expansion rate of the universe. We don't even know what properties dark energy might have. It might be something called "quintessence," about which all we can say is that it acts as a kind of anti-gravity, pushing the universe away from itself.

If we take Jon Stewart's comparison at its most basic, replacing "God" with some kind of generic First Cause, it's not really so far fetched. The first cause is a logical construct that would explain the existence of the universe (though it does raise new logical problems, like what caused the first cause). And at present dark energy is not much more than a logical construct, either, the explanandum in this case being the slightly less sexy expansion, rather than creation, of the universe. Unlike someone like Bill O'Reilly, who ignorantly claimed that science can't explain the tides, or magnets, Stewart is essentially correct here. We don't know why the universe is speeding up, and the words "dark energy" comprise the name we give that ignorance.

Faith is often taken to mean something like "dogmatism." In this sense it has not much value for either science or religion, but is present in each. Even in the best science, humans being what they are, it is never possible to apply the null hypothesis to all our tacit assumptions and motivations. We don't dwell on these excesses, but historically they are many. Behaviorism, for one, which promoted a near-complete lack of affection in child-rearing. The prevalence of pre-frontal lobotomies, for another, in the mid-20th century.

A common response to this line is that what is incidental to science is essential to religion, which is centered upon acts of faith. This is where I think we need to introduce complementary meanings of the word, connoting something more like dedication in the face of the unknown. Anyone who has read Marilynne Robinson knows she was not on the Daily Show to encourage religious dogmatism.

This kind of faith is essential to science. (It is also not unrelated to curiosity and play, though the stakes can be much higher in scientific contexts.) This is the kind of faith a scientist might have in thinking she might redeem the work of prior scientists, or in believing there is a rational explanation for an unexpected observation. These proceed without any certainty regarding the results whatsoever. The greatest discoveries must have required immense faith (in this second sense), so upsetting were they to our common understanding of things. Galileo's discovery of moons around Jupiter, Darwin's discovery of common descent. These required an incredible commitment and dedication to see their work through, and both suffered terribly for it.

It is attractive to believe, perhaps, that religion has room only for the first, dogmatic type of faith, and I cannot and will not argue with the menacing prevalence of it. But to pretend that all of religion is just unreasoned adherences and appeals to authority, while all of science is merely evidentiary, betrays no understanding of how much we know about the sociology of science, and the varieties of religious experience. The "conflict thesis" was once compelling, but given all the data we've been able to accumulate over the 150 years since White and Draper, there's no reason for any educated person to believe it.

16 comments:

underverse said...

[On behalf of Ian Musgrave, who posted this comment on the Australian site]

No, dark energy is not even remotely like faith. It is a tentative hypothesis to explain observations about our universe. It does have less evidential support than Dark Matter for instance, but it does have evidence and is testable. Indeed last year it passed another test.  
http://scienceblogs.com/startswithabang/2011/05/dark_energy_confirmed_again.php  
 
ANY initial hypothesis will have limited evidential support, tentatively accepting the best hypotheses, while continuing to test and refine ( or reject) it is not faith.

underverse said...

Ian,  
 
That blog post you linked to is rife with extremely bad reasoning, consistently confusing the phenomenon (increased acceleration) with the explanation (dark energy). Since the latter is what we are trying to establish, we can hardly start with the assumption that it's the cause of the effect we are trying to explain. Seigel writes:  
 
So if we go and measure how far apart the galaxies in the Universe are spaced from one another, we can figure out ... How quickly the Universe has expanded since, or what percent of the Universe is dark energy!  
 
That last phrase is where the problem lies. Measuring the rate of expansion only re-states the problem, it does nothing to privilege one explanation over another. What is dark energy? Right now it has no known properties except that it is the cause of the cosmos' increased acceleration. That doesn't mean we shouldn't hypothesize about it, but it's a little bit much to say that 70-75% of the universe "is" dark energy, when we have no clear idea what that is, or how it relates to other kinds of matter and energy (not to mention gravitation). The best we can say is that 70-75% of the universe is an unexplained phenomenon, perhaps a property of space itself, perhaps a fifth fundamental force (quintessence).  
 
When I call such a thing faith I don't mean it disparagingly. As I say, science cannot function without tentative commitments to hypotheses. It is a different kind of faith than religious faith, I agree, since the latter does not methodologically go on to verify its propositions. The point is merely that it is premature to categorize dark energy as a scientific fact. It is a very loose hypothesis. Science is rife with such ideas, later discredited, though once supported by some of the best minds (phlogiston, planet Vulcan).

underverse said...

[On behalf of John Wilkins, who posted this comment on the Australian site]

There is, I think, a difference between the kind of faith one finds in religions - where evidence is not required to justify the assertions made - and in science where it is the best explanation or logical implication from evidence and theory that necessitates ideas like dark energy. Personally I find dark energy mildly objectionable, but if it is required by our other knowledge, then I have to accept that as likely to be the case. Can one say this about, say, a religious doctrine?  
 
I reject the Conflict Thesis myself, but there is conflict from time to time, as there must be on sociological grounds. Any two traditions, and institutions, that compete for attention and resources will occasionally conflict. There is no necessity that they do, and history shows religion and science have a sometimes uneasy and sometimes comfortable relationship, but they occasionally try to elbow each other out of the way.

Ian Musgrave said...

Without using the expert fallacy, I would be careful in accusing an astrophysicist of bad reasoning.

More accurate and extensive measurement of the rate of expansion at different scales will more clearly test whether the expansion is due to dark energy or another explanation (eg a change in the force of gravity at different epics), in the same way that measuring ever more carefully the minor fluctuations in the cosmic background radiation allows us to decide between various versions of the big bang.

Again, as you have stated it any initial explanation for a phenomenon is faith. When neutrons were hypothesized as an explanation for certain facts of radioactive decay, it was some time before the hypothesized particles could be confirmed. Your usage of faith would call that period when there were good theoretical grounds to tentatively accept the existence of neutrinos (at least enough acceptance to design experiments to look for them) as faith.

Which is nonsense.

Ian Musgrave said...

On second thoughts, is your complaint more that science communicators don't always preface "our best expnataion currently is ..." before mentioning dark energy? Being brief is not the same as faith.

underverse said...

<span>On second thoughts, is your complaint more that science communicators don't always preface "our best expnataion currently is ..." before mentioning dark energy?</span>

No, because in this case there is no best explanation. I do think there is a problem with scientists presenting as fact that which is essentially speculative. Physicists that say they "know" we'll find the Higgs boson, for example. In the case of dark energy, however, the hypothesis has hardly been articulated. It won't so to say that 75% of the universe "is" something when you can't say what that something is.

<span>More accurate and extensive measurement of the rate of expansion at different scales will more clearly test whether the expansion is due to dark energy or another explanation (eg a change in the force of gravity at different epics), in the same way that measuring ever more carefully the minor fluctuations in the cosmic background radiation allows us to decide between various versions of the big bang. 
</span>

At present, the term "dark energy" covers both of these possibilities. The first is called the cosmlogical constant, the second is called quintessence. I agree that further experiment will very likely clarify the matter. I'm not sugessting we leave it alone as an unsolvable mystery. I'm saying that giving it a name (dark energy) creates the impression there is something out there we have measured that somehow aligns with the other known facts of physics. We're not there yet.

<span>Which is nonsense.</span>

Because you say so? You object to the word because it makes science seem less rigorous, perhaps, or because religous people have foolish ideas and therefore any characterization of faith is a de-facto defamation. But look at the term as I have used it (not as dogma), and tell me how I'm mistaken. Are you saying that good scientists do not have dedication in the face of the unknown?

Ian Musgrave said...

"in this case the is no best explanation" I think physicists will disagree with you, very, very strongly. In this case we have progressed for just observing an increasing expansion, to eliminating instrument measurement errors, to eliminating weird gravitational effect and non-relativistic formulations. The latest set of measurements falls in favor of the cosmological constant version rather than the quintessence version.

Again, I cannot see for the life of me how this constitutes faith.

But then again, have you actually asked either Sean Carroll or Ethan Seigle why they feel that dark eneregy is the best explanation?

underverse said...

<span>Again, I cannot see for the life of me how this constitutes faith.  </span>

You keep reasserting your incredulity, without explaining your reasons. If it is not faith, why not?

At any rate, you are stil overselling. Physists have no concrete idea what dark energy is. Here's Sean Carroll

http://blogs.discovermagazine.com/cosmicvariance/2011/10/04/dark-energy-faq/

There are some broad ideas about what it might, be (which I've never denied). But once you get past saying that it's invisible, non-interactive with matter (apart from the gravitational effect), evenly distributed, and that it bestows a negative pressure on galactic matter, increasing acceleration, it has no other known properties.

Even here, Sean gets a little ahead of himself. He says that we know that the cosmos is 73% dark energy because of subtraction from cosmic backround radiation. All this shows is that 73% of the matter-energy of the universe is not presently accounted for. It might be "dark energy," but as no one has measured or quanitifed it yet, this is really not an empirical claim.

Here's another astrophysicist, Philip Hughes (University of Michigan), who thinks DE thoery is on the right track but  adds “The concept of ‘dark energy’ is a way of parameterizing our ignorance... We have for practical purposes no understanding of ‘dark energy’; there isn’t even a glimmer of consensus.”

I'm not really interested in appeals to authority. If you think dark energy is demonstrable, rather than hypothetical, please feel free to indicate your reasons.

Ian Musgrave said...

Because your formulation means that *any* initial hypothesis for *any* phenomenon from the increased expansion of the universe (dark energy), anomalies in particle decay (neutrinos), to why the muesli bars are disappearing from my cupboard (probably my youngest son demonstrating climbing abilities I was previously unaware of) are *faith*. This definition is so broad as to be meaningless.

Measuring dark energy (or at least distinguishing between competing theories of dark energy) is no trivial task, to be sure. But just because something is hard doesn't mean our provisional acceptance of preliminary results is "faith".

Again, the observations you disparage as being "merely" measuring expansion, measure the rate, spatial and temporal variation of this expansion. This puts very strong constraints on what dark energy is, as I explained before the latest measurements favor cosmological constant versions of dark energy.

What is not at issue here is that our explanations are tentative, this is true of *all* early hypotheses.

underverse said...

I think you are making my point for me. It's broad, yes, but not so broad as to be meaningless. What your examples all have in common is that none is yet supported by enough evidence to warrant scientific fact.

Obviously you are bristling against the word faith, which I am just trying to naturalize here since it has become such a slur, something that only credulous or needful people engage in. Not true. We all must invest in things that can't be firmly established. That includes the practice of science, in the earlier stages of developing and articulating hypotheses. You are mentally adding a disparagement that I do not intend. A certain amount of faith in conjunction with rigor, thoughtfulness, creativity and doubt is nothing to be ashamed of. When it is not balanced by those other qualities (as in many instances of religious belief, or paraspychology, or what have you), we may say it tends toward the more pathological, that more critical thought it needed. But in itself there is nothing intrinsically wrong with committing, provisionally, to unproven propositions. That is the whole of my argument.

I also never said the efforts of physicists in exploring the concept of dark energy were not difficult, clever, rigorous or learned. I just said that thus far they have not yielded the kind of certainty we ask for from scientifically demonstrable facts. Dark energy is as yet a very tentative hypothesis, and is very little consensus as to how it should be formulated.

Ian Musgrave said...

I think you are messing up on what constitutes "scientific fact". Science consists of a series of observations (whether garnered by by"observation" or experiment) with some degree of confirmation and replication. We can call these facts. There is alos a group of theories that explain those "facts" ( as well as a series mod methodologies for obtaining and testing "facts"). As Steven J Gould said, "In science "fact" can only mean "confirmed to such a degree that it would be perverse to withdraw provisional assent".

All explanatory theories fall on a continuum from poorly confirmed to well confirmed, there is no dividing line were you can say this theory is "fact" and that one is not.

Your formulation of "faith" makes all the provisional stages of any hypothesis/theory testing "faith", I sure homicide detetives will be bemused to learn their intial theories in a murder investigation are "faith".

You can tentative accept the conditions of a hypothesis in order to test it effectively (you may do this because you in fact think the hypothesis is likely to be wrong, as in the case of Ethan Seigle) with out "believing" in it.
Again, in the case of dark energy, the evidence (while still tentative) is a lot stronger than you imply. There is a good theoretical reason to suspect dark energy exists (it falls directly out of lambda CDM cosmologies and as I keep writing and you seem to be ignoring, increasingly stringent observations of the rate of expansion eliminate other contenders, and are consistent with either a cosmological constant version or a scalar field version, with the cosmological constant version being the front runner).

When you say "we don't even know what properties dark energy must have" you are dead wrong. Again, there a number of properties it must have (writing on an iPad, so if you go to the Cosmic Variance blog and search for CERN lectures on cosmology and particle physics, then run the dark energy video you will find a lot more detail after the chat about gamma ray Burt's). It's not an explanation pulled out of a hat.

Ian Musgrave said...

Erring, I hate writing on iPads, I spend more time trying to find out where the input system has sent my text, or correcting stupid auto corrects than trying to think.

One thing I failed to make clear is that the understandings of cosmologists don't conform to your new version of "faith" unless it is so general as to covers any human activity where we don't immediately have the answer.

And do we *really* need a new definition of faith? Look at all the trouble caused by the word belief. I believe Jesus is my savior, I believe the sun will rise tomorrow and I believe I'll have a sarsaparilla are all legitimate uses of the word belief whit entirely different connotations. And look at all the trouble we have from people trying to conflate the second usage of belief with the first usage.

underverse said...

If I can breifly try a different approach: a person believing, in the year 1600, that the earth moved around the sun would be correct, and yet all the best science of the time would be against him. Even after Galileo, geocentric models provided better results than heliocentric ones, until Kepler and others were able to resolve the orbit issue.

<span>unless it is so general as to covers any human activity where we don't immediately have the answer.  </span>

I don't have any problem with that. In fact that's my point, that science and religion (or any other human endeavor) don't each need their own words for the same basic phenomenon.


<span>And do we *really* need a new definition of faith? Look at all the trouble caused by the word belief. I believe Jesus is my savior, I believe the sun will rise tomorrow and I believe I'll have a sarsaparilla are all legitimate uses of the word belief whit entirely different connotations. And look at all the trouble we have from people trying to conflate the second usage of belief with the first usage.</span>

That's why we have explicative writing, to clear up these sort of confusions and misunderstandings. Langauge is inherently ambiguous, there's no way around it.

Ian Musgrave said...

Sorry, late reply due to the flu and stuff

By 1600 Tycho had effectively demolished the Ptolemaic heliocentric system. The "crystalline spheres" were shattered by his observations of comets, denying the motive power of the Ptolemaic system. Tycho's observations of the parallax of Mars convinced him that the Ptolemic system was wrong.

The Copenican system had several advantages over the Ptolemaic system well before 1600. It was more elegant, rationally explained both the retrograde motion of the exterior planets and the number and duration of the retrograde sections, the motions of Mercury and Venus, precession of equinoxes, and above all, got rid of the equant. And it made testable predictions.

But Tycho Brae couldn't bring himself to accept the Copernican system because of his religious convictions (I have an extensive blog post on this I shall link to later). So he created a hybrid heliocentric/geocentric system which was simply a mathematical inversion of the Copernican system.

While the Copernican Pruentic tables were mostly only marginally better than the Ptolemaic Alphonsine tables, they were better at some things, like correctly predicting a conjunction of Jupiter and Saturn in 1563.

So an astronomer accepting Copernicus's heliocentric theory in 1600 had good theoretical and observational reasons for doing so.

Ian Musgrave said...

Sorry, late reply due to the flu and stuff

By 1600 Tycho had effectively demolished the Ptolemaic heliocentric system. The "crystalline spheres" were shattered by his observations of comets, denying the motive power of the Ptolemaic system. Tycho's observations of the parallax of Mars convinced him that the Ptolemic system was wrong.

The Copenican system had several advantages over the Ptolemaic system well before 1600. It was more elegant, rationally explained both the retrograde motion of the exterior planets and the number and duration of the retrograde sections, the motions of Mercury and Venus, precession of equinoxes, and above all, got rid of the equant. And it made testable predictions.

But Tycho Brae couldn't bring himself to accept the Copernican system because of his religious convictions (I have an extensive blog post on this I shall link to later). So he created a hybrid heliocentric/geocentric system which was simply a mathematical inversion of the Copernican system.

While the Copernican Pruentic tables were mostly only marginally better than the Ptolemaic Alphonsine tables, they were better at some things, like correctly predicting a conjunction of Jupiter and Saturn in 1563.

So an astronomer accepting Copernicus's heliocentric theory in 1600 had good theoretical and observational reasons for doing so.

underverse said...

Hope you are feeling better!

Keep in mind I didn't say that Ptolemaic<span> models provided better results than heliocentric ones, I said that geocentric models did. The Tychonic model (with Earth at the center) was the widely accepted model of the early 17th century, and the one best supported by the evidence of the time. While it's true that Tycho may have had non-scientific reasons to invest in this model instead of a heliocentric model, it is false that he did not expose it to scientific inquiry. He did consider the heliocentric model scientifically, and found it wanting. The main concern was he absence of parallax, which was not resolved for another century or so. Now Galileo and Kepler suggested a hypothesis to explain the parallax problem: the fixed stars were very distant. But this was just a hypothesis, there was no evidence for it at the time. (Much like our original subject, dark energy!) Tycho's response, based on his measurements was that this model would make the stars far too big. The Copernican response? God can make stars as big as he likes. Of course no one knew how to go about measuring how distant the stars actually were.
</span>

So we have two models with the same predictive power, one adhering to common sense, the other very weird and theoretically problematic (because of the lack of parallax), not to mention the complete absence of evidence of the earth's movement as this would have been understood by the physics of the time. The latter turned out to be true, but given the knowledge and technology of 1600, the best science clearly supported the former.