[Disclaimer — sort of: I’ve been feeling the increasing need to think past the seeping pustule that is our media/politics fail lately, so I’ve been getting my head back to the stuff of my day job, science writing. Of course, it’s impossible to think about science in the US today without drifting onto political territory, so we get there in the end. But most of what follows looks at what one of the truly hot stories in the physical sciences tells us about the way we figure things out about the world. This post, by the way, here slightly edited, was originally published at Scientific American. It was wicked long there too.]
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I’ve been doing a little poking around the matter of the Italian Grand Prix (neutrino division). Plenty has been written about this already, of course, but what strikes me a few weeks into the story is how effectively the response to the announcement of a possible detection of faster-than-light neutrinos illustrates what actually goes into the making of a piece of science. That, of course, also sheds light on what it looks like when the intention is not to create understanding, but to obscure it.
First, to the neutrinos themselves. For many of the actually knowledgeable folks I talk to (i.e., not me) the question about infamous Faster Than Light gang of neutrinos is not if they’ll be found out, but when.
That is: while the experimental technique reported in the OPERA measurement is good enough to be taken seriously, many physicists note that challenges to special relativity have a very poor track record. A number of other observations would have to be radically reinterpreted for the measurement of the travel time of neutrinos from CERN to Gran Sasso to stand up as an authentic discovery of faster than light travel. See my earlier post on this subject for a bit of background and some useful links.
An example: the OPERA result, if it holds up, would complicate (to say the least) the interpretation of the hugely wonderful detection of neutrinos emitted in the stellar collapse that produced Supernova 1987a. As the parent star of the supernova collapsed, the catastrophe produced 1058 neutrinos, give or take a couple. In what was dubbed the first triumph of neutrino astronomy, three detectors at widely separated locations detected a grand total of 24 of those (anti)neutrinos, all arriving within 13 seconds of each other.
Those neutrinos did reach planet earth before light from the supernova blast arrived. But that quirk of timing has nothing to do with faster than light travel. Rather, it turns on the details of supernova physics. Neutrinos are produced in the initial stellar collapse, and because neutrinos interact with basically nothing — they are untouched by either the strong nuclear force or electromagnetism — the supernova-neutrinos sped out from the dying star more or less at the moment of the blast. Light, by contrast is electromagnetic radiation – and readily interacts with charged particles.
That property caused the light of the supernova to crash around the interior of the evolving supernova explosion as photons interacted with all the extremely electromagnetically energetic matter at hand – a dance that held them up for a time. After a few hours, that light escaped from the interior of the supernova blast and could begin an uninterrupted journey our way. But by that time, it lagged behind the neutrino signal, which is what produced the gap between the neutrino and optical detections of the event.
Think of it as gridlock in the midst of a stellar rush hour — an obstruction 1987a’s neutrinos, riding on (highly metaphoric) rails, were able to avoid. The fact that the two signals arrived only hours apart simply means that the neutrinos travelled at or very close to the speed of light — not faster than. If the neutrinos traveled faster than light – even at the rather small excess suggested by the OPERA experiment — they should have arrived much earlier than they did – four years or so before the light from the explosion.
Now there is a way out of this seeming contradiction, because the supernova neutrinos were significantly less energetic than the ones measured in the OPERA experiment — so it’s not accurate to say that both results can’t be true. But even so, were superluminal neutrinos to prove to be real, then whatever new physics that might be invented to explain the result would have to do so in a way that still allowed Supernova 1987a’s neutrinos to behave as observed.
That’s the problem for any challenge to a fundamental pillar of knowledge: if the new observation is correct, it must be understood in a way that accommodates all the prior work consistent with the older view that is under scrutiny. As physics popularizers always note: Einstein’s account of gravity — the General Theory of Relativity — delivers results that collapse into those of Newton’s earlier theory through the range of scales for which Newtonian physics works just fine. If it didn’t, then that would be a signal that there was something wrong with the newer theory.
Hence the stakes here. Given that special relativity — the concept at risk if superluminal neutrinos turn out to exist — has been described to me by a physicist friend as more a property of the universe than a “mere” law of nature, it becomes clear, I think why this result is so fascinating. If neutrinos really do go faster than light, then there’s a huge challenge to come up with a theoretical account of what’s going on that allows OPERA’s neutrinos the ability to race whilst Supernova 1987a’s crew dawdled along at mere light speed — to name just one issue that would need resolution.
That is: facts on their own are orphans. They require a conscious act of decision on the part of their interrogator to gain meaning. In an essay published the same year Einstein proposed special relativity, the great mathematician and physicist Henri Poincare asked “who shall choose the facts which…are worthy of freedom of the city in science.” For Poincare, the answer was obvious: that choice “is the free activity of the scientist” — which is to say that it falls to a theorist to think through how one fact, placed next to another, fits into a coherent framework that can survive the test of yet more facts, those already known and those to be discovered.
All of which is to say that even before the Italian observations stand or fall on attempts to replicate the finding, theoretical analyses — thinking hard — can go a some distance in determining whether superluminal neutrinos prove “worthy” of a place in science’s city.
And that’s the long way round to commend a really excellent piece by Matt Strassler, an old friend whose day job as a theoretical particle physicist at Rutgers informs his recently acquired mantle as a physics blogger. Check him out — not just this post — because, IMHO, he’s very rapidly proving himself to be in the first rank of popular translators of some really deep stuff.
In the linked piece, Matt writes about an argument put forward by Andrew Cohen and Nobel Laureate Sheldon Glashow, both theoreticians at Boston University. To gloss Matt’s explication: Cohen and Glashow have developed some earlier thinking that originally focused on the phenomenon called Cerenkov radiation. Matt discusses Cerenkov radiation here — basically it’s electromagnetic radiation emitted by energetic particles going faster than the speed of light in a medium (water, or air, for example, rather than a vacuum) — which, as Matt explains, does not violate special relativity.
Neutrinos do emit such radiation, very weakly, but that’s not the key to the argument; the effect is too small to matter for the OPERA result. Rather, Cohen and Glashow point out that superluminal neutrinos should have produced a different kind of emission that is roughly analogous to the Cerenkov effect — and that each time one of OPERA’s neutrinos did so, it would have lost a lot of energy — enough to register on OPERA instruments. Which means, as Matt puts it, that
… the claim of Cohen and Glashow is that OPERA is inconsistent with itself — that it could not have seen a speed excess without an energy distortion, the latter being easier to measure than the former, but not observed. The upshot, then, is that OPERA’s finding that its neutrinos arrived earlier than expected cannot be due to their traveling faster than the speed of light in vacuum. Something is probably wrong with OPERA’s expectation, not the neutrinos.
Now this is a theoretical argument and it could be wrong in a variety of ways. In the comment thread to Matt’s post, the very clever physicist Lee Smolin points to one possible physical case in which Cohen and Glashow’s proposition would not hold. Theory, interpretation, decides what facts are worthy of being known — but theories are subject to revision, of course, and never more so on those occasions when one fact or another stubbornly refuses to submit to judgment.
But what I find so pleasing about this whole sequence of thought is the way it illustrates what actually happens in science, as opposed to the parody of scientific process you see in a lot of public accounts — especially when politically contentious research is involved.
The OPERA team made the best measurement they could; when it refused to succumb to their search for some alternative explanation, they published the result, no doubt reasonably certain that it would be subject to relentless examination — under which there was (and remains) a very good chance this work will be shown to be wrong. Cohen and Glashow have now offered a formal structure that suggests that what we know of the way the universe actually works presents a major logical challenge to the validity of the OPERA claim of discovery. The ultimate resolution will turn both on continuing experimental work and on the kind of effort Glashow and Cohen offer: the hard work of figuring out what it would mean if the result were true — or perhaps better: what understanding do we possess now that suggests the OPERA result is either real or an error.
Contrast that process with the critique of climate science that comes from the Right, as I discussed briefly in my post on Eric Stieg’s rather blistering review of the recent announcement of a study affirming (yet again) mainstream climate research. Stieg wrote, in effect, that the attacks on climate science turn on a refusal to engage one blunt fact: there is an underlying physical understanding of the basic theory of the system under study: climate change driven by changes in the chemical composition of the atmosphere. That theoretical framework determines the course of empirical research, the search for facts worthy of being known:
…the reason for concern about increasing CO2 comes from the basic physics and chemistry, which was elucidated long before the warming trend was actually observable…The warming trend is something that climate physicists saw coming many decades before it was observed. [Italics in the original.] The reason for interest in the details of the observed trend is to get a better idea of the things we don’t know the magnitude of (e.g. cloud feedbacks), not as a test of the basic theory. If we didn’t know about the CO2-climate connection from physics, then no observation of a warming trend, however accurate, would by itself tell us that anthropogenic global warming is “real,” or (more importantly) that it is going to persist and probably increase.
Which is another way of saying that most of the noise from those who both deny the reality of climate change and would impugn the honor of climate researchers misses the point. Not because there isn’t reason to test the reliability of any measurement — of a fast neutrino or a tree ring sequence, either one — but because the issue in either case is understanding what we do know, and then engaging the challenge of a new result in that context.
Hence the (perhaps meta-) value of the faster-than-light neutrino story. This experiment will have to overcome the hurdles thrown up by special relativity’s ubiquitous influence, by the physics of high energy phenomena and so on. That’s how the process of discovery moves from tantalizing initial impressions to settled knowledge. Understanding that process illuminates the hurdles facing climate science denialists: to advance their case, they must reconcile their criticisms of mainstream climate research with the exceptionally well understood basic physics of radiative transfer and the thermal properties of different gases — as well as streams of evidence flowing from direct observations and from the ongoing inquiry into the correlation between evolving climate models and what we can see of the climate itself.
By contrast: cherry-picking dishonestly-excerpted emails is not science.
Oh — and as long as we’ve come this far, let me add a note about another challenge to the faster-than-light neutrino claim that’s come up over the time I’ve been working on this post.
In one of dozens, at least, of efforts to pry apart the actual workings of the OPERA experiment, University of Groningen Ronald van Elburg, has offered his candidate for the (by-many) expected systematic error that could have tricked the OPERA researchers into believing they had observed an effect that is not there.
Elburg has zeroed in on one of the obviously critical elements of the measurement, the calibration of the clocks that timed the neutrinos on their journey. To make that observation, the team relied on the atomic clocks used to synchronize the signals from Global Positioning Satellites — GPS. The tricky part is that the satellites that house the clocks are in motion — pretty fast too — relative to the labs on the ground and the neutrinos traveling between the source and the detector.
When one object is in motion, travelling in a different reference frame than that of some measuring apparatus, then special relativity comes into play. As the TechReview’s Physics ArXiv blog describes the issue, this means
[that] from the point of view of a clock on board a GPS satellite, the positions of the neutrino source and detector are changing. “From the perspective of the clock, the detector is moving towards the source and consequently the distance travelled by the particles as observed from the clock is shorter,” says van Elburg.
The correction needed to account for this relativistic shrinking of the path as seen from the point of view of the measuring device in space is almost exactly the same size as the seeming excess speed of the neutrinos the OPERA team believes they’ve detected. And that would mean that…
far from breaking Einstein’s theory of relatively, the faster-than-light measurement will turn out to be another confirmation of it.
It’s not as open and shut as all that. Elburg’s argument makes the assumption that the OPERA team failed to account for the quite well-known special relativistic effects on GPS signals — and while they may have, we don’t know that yet. At the same time the original OPERA paper reports some checks on the timekeeping essential to the experiment. I understand that the group is working through the long list of necessary responses to specific suggestions like this one — while at the same time preparing for a yet higher precision measurement of the effect they think they have seen.
But the broader point remains: experimental physics is (and has always been) very, very hard to do, involving an effort to push the limits of precision beyond any current standard. Because the effects sought are at the limits of our capacity to detect them (necessarily; if it were easy, we’d have seen whatever it was already) there is an enormous amount of subtle knowledge that goes into constructing the framework of each experiment. The machines don’t just have to work; you have to understand in detail how quantum mechanics and relativity and all the increasingly subtle applications of the broad ideas play out at the speeds and energies and distances involved. Understanding what’s actually happening at the subtle edges of experiments — even seemingly simply ones — turns out to be very difficult to do.
How difficult? So much so that Albert Einstein himself made an error that is quite similar in some ways to the mistake Elburg suggests could have happend here. In 1930, in one his famous arguments with Niels Bohr, Einstein devised a thought experiment to show that it would be possible to measure a quantity to a finer level of accuracy than Heisenberg’s Uncertainty Principle permits. Einstein’s argument seemed airtight, and according to an observer at the scene,
It was a real shock for Bohr…who, at first, could not think of a solution. For the entire evening he was extremely agitated, and he continued passing from one scientist to another, seeking to persuade them that it could not be the case, that it would have been the end of physics if Einstein were right; but he couldn’t come up with any way to resolve the paradox. I will never forget the image of the two antagonists as they left the club: Einstein, with his tall and commanding figure, who walked tranquilly, with a mildly ironic smile, and Bohr who trotted along beside him, full of excitement…The morning after saw the triumph of Bohr.
It turned out that Einstein had left one crucial physical idea out of his analysis; he did not account for the effects of his own discovery, the general theory of relativity, on the behavior of the experimental procedure. Once gravity was factored into the argument, the violation of quantum indeterminancy vanished.
That is simply to say that the neutrino experimentalists may well have made what seems from the sidelines like an obvious mistake. But if Albert Einstein could fall prey to a similar kind of error, that should tell us all we need to know about how hard it is for any one person, or even one group, to think through the full subtlety of experience. Which is why science works the way it does, by continuous criticism and self-criticism. As the neutrino story plays out, we’re watching how science ought to work.
Which, and finally we complete the long road home, is why science honestly done and described is vastly different as both a practical and a moral matter than the masked-as-science attacks on this mode of discovery that now dominate the thinking of one of the two major American political parties.
Images: William Blake, When the Morning Stars Sang Together, 1820.
Jan Vermeer, The Astronomer, c. 1668
Brachiator
There once was a fellow named Bright,
Who could travel quite faster than light.
He set out one day
In a relative way,
And arrived on the preceding night!
Great explanation of this issue.
Villago Delenda Est
This is one long fucking post.
But the final point rams home one of our major problems.
One of the two major political parties is filled, beyond capacity, with shitheads.
Keith G
No apologies necessary. I could use some brain food. That, and sometimes post around here can get into a bit of a rut of superficiality and snark.
Libarian
If you go to Einstein’s house in Princeton today, at 112 Mercer St, the front gate has a sign reading “Private Residence”- I assume, for tourists who think the house is a museum or something. Einstein expressly forbade turning the house into a museum or shrine in his will.
Poopyman
@Villago Delenda Est: Actually, the capacity is yet to be determined, but I’m betting it ain’t overflowing yet.
But seriously Tom, this post represents a shit-ton of work, well constructed, and including a well thought out backstory. You gots talent!
Redshift
I ran across this the other day at SciAm! I was wondering when you’d pimp it here (please continue to do that, whether you re-post or not.) I was interested based on the headline, and then it was “hey, I know that guy!”
I enjoyed it thoroughly.
Joey Maloney
@Brachiator:
There was a young fellow named Fisk
Whose sex was exceedingly brisk
So fast was his action
Fitzgerald contraction
Reduced his rapier to a disk
kindness
I get that theoretically nothing is supposed to be able to travel faster than light (well, here neutrinos) because they have almost no mass & as such can go fast. Anything with mass, by extension would require much greater amounts of energy in order approach the same speeds.
How does that explain other civilizations visiting Terra then? All you shaking you heads can ignore me here on out.
I am one of those that thinks we aren’t alone in this universe. I have to believe in the billions of galaxies other sentient life exists. Would it make more sense for those more advanced than we life forms have found a way to bend space (a la the Dune series ‘jumps’)? The energy requirements for bringing a ship to over light speed would still leave it traveling the universe for hundreds of years. I doubt that is what happens. I just don’t see it for an exploring species.
What do you all think (if you even dare to go here)?
JGabriel
Tom, thanks for sharing this with us peons and geeks here at BJ.
.
Skipjack
@kindness:
Aren’t you kind of begging the question? If you see how nothing can go faster than light, doesn’t that mean your default position should be that we haven’t been visited until someone can explain how that might have happened? Whether there are other sentient beings out there or not.
PS Also @Tom, thanks for this I will read it more carefully again later, and I hope to see more posts like this here in the future. It certainly breaks up the routine.
RSA
This is really excellent, Tom. I love what you’ve done: You’ve combined a new discovery in the news with enough background for a casual reader (including an engaging historical anecdote), and the entire piece conveys some insights from the philosophy of science.
cmorenc
@kindness:
Yes, the probabilities ARE quite good that among the uncountable billions of galaxies across the universe, each with billions of stars, there is life (perhaps even intelligent life, perhaps even more advanced intelligent life than our own) out there.
NEVERTHELESS it does not follow from even the most certain presumption that other intelligent life exists out there that it is located within physically accessible range of any of the rest of it elsewhere, or even within range of any detectable signals from one another. Nor especially does it necessarily follow that even the most advanced among other intelligent life forms out there has solved the problem of overcoming the speed limits of relativity to visit the realm of any other locations with intelligent life (or perhaps even other simpler life period). Nor does it necessarily follow that any of them have solved the difficult problem of transmitting a powerful enough, sustainably focused enough communications signal to detectably reach any other alien civilization, let alone one advanced enough to receive and understandably recognize it for what it is.
The far greater probability is that even though other life, even intelligent life is likely out there somewhere within the realms of other galaxies we can see with our telescopes (albeit, the light from which we see them now is a few million to several hundred million years old)…we are effectively alone, forever, in the universe, out of reach of anyone else from anywhere else.
kindness
@Skipjack: You’re telling someone who believes we have been visited that I should instead change my beliefs to we haven’t been visited until we can figure out the physics of interstellar travel? Really?
@cmorenc: Better and more plausible response but still ignoring the belief that I already have.
Just because we don’t know something doesn’t automatically mean it can’t exist or happen. My view is we just don’t know how yet. I guess I was asking if anyone else had thought it through. I mean, I’ve seen things in the night sky that can not be explained by planes, satellites of comets. No, never been visited.
TuiMel
Tom,
I like reading your stuff, but can you put more of the posts “after the jump”? These long front page posts are murder for scrolling through what’s on the front page. Thx
Scamp Dog
@kindness: The universe is hugely big, but keep in mind that it while life on Earth took hold early (about 3.5 billion years ago), it took another 1.8 billion years to become multicellular. To top it off, the Sun is gradually getting brighter, and in a half billion years or so, Earth’s oceans will boil away, and that will be the end of things.
So any intelligent species only has so much time to figure out interstellar travel, and given our political system’s inability to acknowledge, never mind deal with, global warming suggests that we’re going to botch our chance. Your cheerful thought for the day!
SiubhanDuinne
Tom, I always come away from your posts feeling about 10 IQ points stronger. You write so clearly and elegantly, it is just pure pleasure to read your articles. And as a Blakebot, I want to thank you for including When the Morning Stars Sang Together. It’s one of my all-time favourites.
Edit: Nice to see what you look like in the SA addendum.
tothemainerborn
To quote Enrico Fermi, “Before I came here I was confused about this subject. Having listened to your lecture I am still confused–but on a higher level.”
Nice piece of writing on an interesting subject, Tom.
Skipjack
@kindness:
Exactly! Yes I am asking you to admit that you are propounding two contradictory ideas at the same time. I am not asking you to deny that our understanding of the possibility of interstellar travel could ever change but at least to come at it from the perspective that it’s problematic to conclude we have been visited. If we can’t debate from what we know there probably isn’t anything to talk about, unless you want to talk about religion.
But I’ll bite, what makes you think we have been visited, and not that there are likely to be other civilizations but that they could get here and perhaps left behind some proof?
SiubhanDuinne
@cmorenc:
No Republicans, huh?
Bill E Pilgrim
I’ve said from the start that violation of Einstein’s speed of light constant, while breathtaking, wouldn’t be nearly as shocking as the idea that anything arrived early for an appointment in Italy. So, I’m going with instrumentation.
Tom Levenson
@TuiMel: Sorry. I guess when you have a 3k word post,measuring where to put the break by proportion of the text is not so useful.
Many thanks to all the kind words folks.
(Edit: Bill E Pilgrim for the win! He knows the Italy whereof he speaks.)
Cermet
I’ll add one very critical physics fact – relativity DOES NOT prohibit faster than light speeds, only an object with rest mass achieving the speed of light. This is not important because to go faster than light, then one must go the speed of light first and that creates a rather big problem. The theory says nothing about the impossibility of exceeding light speed as long as the rest mass particle does not have to go the speed of light. Of course, travel at speeds greater than light requires negative energy or negative mass and those are rather strange properties.
Roger Moore
As a practitioner of another branch of science, I’d like to point out that this problem is by no means limited to physics. Generating really high quality data, especially in an area that has been picked over for a long time, is always incredibly finicky and requires a different mentality from other forms of research.
As an apropos example, one of the problems climate researchers struggle with is that they’re looking for signal in very noisy data. The noisiness of the underlying data and the need for extensive cleaning up is one of the things denialists use as a way of throwing up a smokescreen.
Anoniminous
First: informative article, thanks.
People may be interested to know this week a major, tremendously important, breakthrough occurred wrt Alzheimer’s and, perhaps, a whole bunch of other neurological diseases.
middlewest
@kindness: Why don’t you just ask your magical alien friends when they show up to probe you at night?
Roger Moore
@kindness:
I think you need to reconsider your assumptions. Which seems more likely:
1) There’s an unknown (to anyone) way of traveling faster than light that has allowed alien civilizations to visit Earth, they’ve visited and left indications of their presence that you have observed, but they’ve decided for some reason or other not to announce their presence generally.
2) There’s an unknown (to you) explanation for phenomena that you believe are the result of alien visits that doesn’t involve aliens.
I’m going to go with #2 as being sufficiently more likely that #1 can be dismissed until there’s some much more concrete evidence of alien visitation.
Tom Levenson
@Roger Moore: There are some who would say that the existence of Mitt Romney is in fact evidence of alien visitation.
Bill E Pilgrim
@Tom Levenson: Let me just add my kudos also, going to read this more thoroughly later also.
Re Italy yes, experience-based snark, not reputation based :) My friends in Rome wear it as a badge of honor. Though actually the record was a guy in Milano in the industrious north who was 24 hours late for an appointment. Around noon, as we’d planned, but …the next day. And it wasn’t like “oh yeah I had to change to today”, it was more like “Yeah, sorry I’m late”.
Brachiator
This may also be a good place to note this story, on the importance of integrity in scientific research.
GR
Tom,
As a physicist (though not the neutrino-hunting kind!) I can’t tell you what a pleasure it is to read such an eloquent post about developments in the field. You really have a gift for the science-writings. Thanks for sharing this article, we need more science writers like you.
At some point, I’d really like to understand the genesis of the anti-science movement in the Republican party. I’ve read Hofstadter, and I guess that sort of describes it, but it seems like even in his day conservatives placed some value on science (if only for its ability to make things that go boom). The specific and fierce vitriol towards science and scientists coming from the right nowdays has always befuddled me.
And as far as precision measurements go, people who do that are nuts (in a good way). Having to worry about things like the concrete in the floor under your experiment expanding and messing up your measurement takes a very special kind of person…
RSA
@GR:
Me, too. My disorganized thinking on this divides up science haters into a few not-necessarily-separate categories: (1) those who find conflicts with their religious beliefs; (2) those who dislike being told that they’re wrong, on any subject; (3) bullshitters (per Harry Frankfurt)–those who find it easier to convince people of some point of view if their audience doesn’t have any notion of what’s reasonable or not.
cmorenc
@SiubhanDuinne:
No, there are no Republicans, but there are Klingons.
THE
@Tom Levenson:
Not necessarily. There is another way out of this conclusion: We can observe that there is a hidden assumption operating here. The assumption is that the effect of light slowing-down or neutrino speeding-up is a cosmological effect.
But it may not be. What if it is limited to our Galaxy, perhaps as a weird property of Dark Matter?
Or what if it is a local effect of gravity. e.g. there may be a short-range massive graviton as well as the long range kind. Then it may be only a local effect, within our Solar System say.
So I think I would not rule out the effect on the basis of the 1987a observations.
Nature is what it is. And we have to: a) accurately observe it and b) figure it out.
I only hope to be open-minded and detached on this neutrino question.
Nature is never wrong. Our experiments, not so much.
Roger Moore
@GR:
I don’t think it’s a hatred of science per se. It’s more like a toddler’s refusal to accept anything that prevents him from getting his own way. The hallmark of today’s right wing is that they know all the answers and are just looking for a set of facts that will support the answers they want to hear. They’ll happily quote any scientific study that appears to support their ideas or can be twisted to sound as if it supports them. It’s only when science says something they don’t want to hear- the bible isn’t literally true, the tobacco industry is killing people on a massive scale, we need to cut back on fossil fuels, etc.- that they turn on it. If the right seems to be more and more hostile toward science, it’s because they’ve become ever more set in their beliefs and ever less willing to listen to unwelcome news.
Rome Again
@Scamp Dog:
We are but one blade of grass sitting on a Wimbledon tennis court.
RossInDetroit
I think it’s a great article. Translation: I didn’t get lost once. This makes you superior to Lisa Randall, Brian Greene and Stan Gibilisco, all of whom left me in the weeds.
ETA: I’ve bookmarked Matt Strassler and will look forward to digging into those posts. I love this stuff!
Maude
@Roger Moore:
This
mclaren
If you’re interested in this sort of thing, you might also find intriguing an arxiv article that explains how a surplus of high-energy cosmic rays and gamma rays may reveal details about the quantum structure of discrete spacetime:
Cosmic rays and TeV photons as probes of quantum properties of space-time.
And this article, which gives an overview of the physics literature on quantized space-time.
The small-scale structure of space-time: a bibliographic overview.
Neither of these articles requires much math, particularly the second, so they’re accessible to laymen.
dmsilev
Love you, Tom, but this:
is unfortunately incorrect.
Elburg made a number of mistakes in his paper, enough that it’s clear he didn’t understand either GPS or OPERA. GPS is inherently corrected for both the special relativistic effects that Elburg relies on and for smaller general-relativity-based effects as well. If those corrections weren’t built into the timing signals, any GPS measurement made anywhere would have major position errors. Taking Elburg’s 32 ns timing error as correct, that’d be an automatic ~30 feet of position error for every GPS measurement across the entire system.
Secondly, OPERA did a sanity check on their GPS-synched clocks. They took a portable atomic clock, synched it in one lab, trucked it to the other, checked the synch with that clock, and then moved it back to the first to recheck. That procedure was explicitly stated in the OPERA preprint, and would have exposed an 32 ns error easily (they estimate a relative clock uncertainty of something like 2 ns).
As you said, there’s very likely something wrong with the OPERA results, but it ain’t as simple as Elburg’s model.
Tom Levenson
@dmsilev: Love you too, and I did try to indicate exactly the doubts you specify. Hence the mention of OPERA’s time checks, and that it seemed unlikely that special relativity had somehow escaped the OPERA team.
You are right that I should have made it clearer that relativistic corrections are built into the time signal from GPS satellites — as they have to be, of course, if the geolocation they provide is to be accurate. (Tough to land a plane if you have errors in your positioning of the scale that would result from either an uncorrected special or general relativity calculation…)
There are lots of other proposed sources of systemic error out there — and OPERA has answers for a lot of them, certainly. (I’ve heard of one that asked if the team had corrected for the resistance of the wiring in the experimental set-up. They had.)
The best one I’ve heard about so far I learned in conversation with Bob Kirshner last night. There’s a suggestion that there is a general relativistic effect from the difference in GR field strength at CERN and Gran Sasso. If that were unaccounted for…
And, of course, we don’t know yet if it was or wasn’t.
So, yeah, perhaps more bluntness would have been appropriate. But I hope the sense that this was unlikely to be the resolution came through. If not, then definitely more bald statements.
Jamie
John, this place is going to hell. What’s the matter with you? You’re letting real science journalists get in the way of petty snark now?
BrianM
Excellent writeup, Tom.
Regarding: “[the new observation] must be understood in a way that accommodates all the prior work consistent with the older view that is under scrutiny”. As an amateur in these things, I’m curious what you think about Lakatos’s counter to that: “Theories grow in a sea of anomalies, and counterexamples are merrily ignored.” (For and Against Method, Motterlini, p. 99). He uses as an example Newton’s theory of gravitation, which was refuted by existing data on the orbit of the moon from the Astronomer Royal. According to Lakatos, Newton invented his theory of refraction as something of a defensive move: the corrections it supplies to the Astronomer Royal’s data make that data match Newton’s earlier theory’s prediction. Because of your Counterfeiter book, I thought you might have insight into that claim.
There’s also a similar claim by Feyerabend in Against Method. He points out that a flaw in Galileo’s theory of motion (vs. the earlier Aristotelian theory) is that it has nothing to say about a huge range of phenomena that the earlier theory took into account. The Aristotelian theory can be applied to the growth of plants or why fire leaps upward; Galileo’s cannot.
Both Lakatos and Feyerabend are about allowing scientists to retrench, to live with contradictory results whilst they develop their new ideas and their implications.
Of course, both Lakatos and Feyerabend are writing about big, heroic new theories, not how one experiment fits into the larger pattern of science. What you’re writing about fits nicely with Latour’s Science in Action. A lot of that book is about refuting the claim that a single experiment can bring down a theory (the naive Popperian view). Both you and Latour point out that there’s a huge amount of… inertia… that a refuting experiment must overcome. You concentrate on the inert facts from other observations (like Supernova 1987a) and what the implications of the new experiment would mean for them, and also on what other theories would have to say if the claims of the experiment were true (the Einstein/Bohr example, Cerenkov radiation). As a sociologist, Latour doesn’t restrict himself to the kind of “noble inertia” that you do (that is, he includes things like empire-building and the need to keep publishing as parts of the inertia), but what interests me is that both of you are concerned with why science works and give the accumulation-of-things-that-must-be-taken-into-account as one of the reasons.
(Although Latour got lumped in with the relativist bad guys in the Science Wars, I think that was because of the either/or nature of the times: anyone who complexified the idea that the reason science works is because its goal, truth, is identical to its method got lumped in with people who denied truth entirely. There was a distasteful modern-conservatism feel to the whole Science Wars: like the conservative’s rejection of evolution because it violates a pre-existing self-image and besides, think of what it will license the children to do!, the Other Side in the Science Wars were rejected because of the implications of what they said, not because of what they said. Also because of nut-picking.)
Um, I ramble. Blame the insomnia.
deep cap
Yeah, but but but… Al Gore is FAT!
Roger Moore
@BrianM:
I think a lot of what Tom is discussing here is exactly the kind of response that Lakatos is talking about with his protective belt surrounding the hard core of any theory. The reason that anomalies are routinely ignored is because most of them can be explained by altering a subsidiary hypothesis- what Lakatos calls the protective belt- rather than the core theory. In many cases, those changes are at the very edge of the protective belt, e.g. the assumption that an experiment that produced an apparent anomaly was correctly performed and accounted for all sources of systematic error.
That’s where we are right now. Physicists aren’t exactly ignoring the new results. Instead, they are trying to account for them within the protective belt rather than by altering the hard core of the theory. Even if they aren’t able to come up with any specific objection to this experiment, they’re likely to treat it as a case of an experiment with an as yet unknown error (i.e. ignoring the anomaly) until the results are replicated by a separate experiment. Only when there are several results from genuinely different experiments, ones that are unlikely to suffer from the same unknown experimental error, will physicists start taking the results as a serious challenge to their theory.
PatrickG
@GR:
DISCLAIMER: the next paragraph is NOT me playing the ‘both sides do it’ card.
Don’t forget that this is not just a phenomenon occurring on the Right. While they hold all the trademarks on the phenomenon, they’ve generously lent out their proprietary position to groups not necessarily affiliated with the Right (e.g. the anti-vaccination crowd, the homeopathy crowd**, and other such groups that adamantly reject method and evaluation in much the same way the Right does).
FURTHER DISCLAIMER: In no way am I trying to accuse other groups of perpetrating anything on the scale of the wholesale rejection of empiricism by the Right, or excuse the Right in any way, but I did wish to point out they don’t have an exclusive monopoly.
Anyways…
My only vaguely original contribution is an observation that many people have come to equate the Scientist as an authority figure equivalent to the Priest. The latter is a source of received wisdom; the former is decidedly not.
However, once one comes to identify the Scientist as such an authority figure, one can challenge scientific findings on exactly the same basis that one can evaluate which sect of a religion has the Truth, or which political party will defend the American Way in the Face of All Odds, i.e. a self-selection of authority figures and rejection of contrary viewpoints. In short, tribalism and self-service, without an ounce of self-awareness.
* I really hate myself for using the phrase ‘rich tapestry’, but I confess to hasty commenting in a forum without rigorous peer review. :)
** I refer here to that particular brand of ‘medicine’ that uses tradition as authority and discounts more modern developments. I should probably have used a word other than homeopathy, but I’ve had some really irritating encounters with people who were way too fond of that word, so eh. I’ll just assume that people know what I’m talking about, reflect on the folly of stream-of-consciousness commenting, and head to that dinner I’m late for.
moderateindy
Tom: Yes, exactly, wait a second………..neu-whatos? This sciency stuff makes me feel icky. I think I’ll go back to watching football.Defense, Defense. Besides, I’m pretty sure that heat from the sun is just a warm hug from Jesus
mclaren
@PatrickG:
Yes, sadly the Left has its own anti-science cranks too. You didn’t mention the Frankenfoods activists who mutter dire doomsday predictions about genetically modified foods…apparently without realizing that every single grain staple humans eat today has been extensively genetically modified by selective breeding over thousands of years. Carrots, peas, tomatoes, potatoes, wheat, barley, soy beans, maize, corn, all have been selectively bred for thousands of years to radically genetically modify these foodstuffs.
Then there’s the anti-nuclear crowd on the left. I’ve got news for them: liquid thorium breeder reactors are the only power source on the horizon that gives promise of an affordable solution to Peak Oil. Solar-electric and solar-voltaic are simply too expensive, and depend on rare earths too scarce (indium, for example) to represent a practical solution to Peak Oil. Replacing America’s electricity generated by coal and natural gas, for example, would require more than the world’s existing supply of indium just for the solar cells.
Then there are the Left activists ranting about the alleged “rape culture” of violence against women and the so-called violence of Western civilization. As it happens, statistics show that violence in Western democracies has plummeted over the last few decades. No one has come up with a good explanation, but one thing we do know — violence isn’t up, it’s way down in the first world countries. That includes rape. Statistics is a science and the stats show that violence in our alleged rape culture is way down over the past few decades, and still dropping.
And of course there are the Noam Chomsky leftists who portray America as a satanic force for evil that has tortured and murdered its way across the world. Well, America’s foreign war record is distinctly mixed. Our intervention in Cuba has probably a good thing overall; America’s Mexican war had ugly results, the acquisition of the southwestern states and California notwithstanding. America’s invasion of the Phillipines was truly ugly. But if America hadn’t intervened in WW I, can you imagine how much uglier the Treaty of Versailles would’ve been if Britain & France had been allowed to exhaust themselves against a savagely razed Germany?
America’s decision to fight the Korean War resulted in a thriving democracy in South Korea today. Should we have left North Korea conquer it? Obviously the Viet Nam war was a disaster…but Desert Storm turned out well. The 2003 Iraq invasions was insane and pointless and evil, but America’s participation in WW II saved democracy in Europe and had excellent results in Japan and Germany and Italy. So the record of American foreign wars is mixed. Some turned out very badly, some turned out very well. The Noam Chomsky position of “America as the focus of evil in the world because of its savagely brutal imperialist warmongering” just doesn’t stand up to historical scrutiny. Insofar as history is a science based on observable facts, the leftists who portray America as an imperialistic warmonger throughout its history just get the science of history wrong.