Thursday, January 30, 2014

If it quacks like a black hole

Unless you’ve been sitting in a white hole, you probably read somewhere that Stephen Hawking now claims black holes don’t exist. I was about to close my eyes and let this wave of media nonsense pass over me, but even my mother asks what that’s supposed to mean. So here is the brief explanation.

It is often said that a black hole is defined by the presence of an event horizon. The event horizon is the boundary of a region from which no information can escape, ever. The relevant word to pay attention to here is “ever”. The event horizon is a mathematically well-defined property of space-time, but it’s a mathematical construct entirely. You would have to wait literally till the end of time to find out whether an event horizon really is an event horizon in the sense of this definition.

Instead of the event horizon physicists thus often talk about the apparent horizon. The apparent horizon is, roughly, something that looks like an event horizon for a finite amount of time. Since all we can ever measure of anything can be done only in finite times it’s the apparent horizon that we ask for, look for, and observe.

For all practical purposes – and with that I mean actual observations of astrophysical black holes – the distinction between apparent horizons and event horizons is entirely irrelevant. Which is why you and probably many science journalists have never heard of this.

That actual event horizons might not be formed when matter collapses, but only apparent event horizons that eventually vanish, is not a new idea. It’s been discussed in the literature since 20 years or so. In my paper with Lee, we discussed the option of there being no event horizon but only an apparent horizon on very general grounds. See Fig 3, read caption, for further literature check references.

So what then did Hawking mean? The actual quote is:
    “The absence of event horizons mean that there are no black holes – in the sense of regimes from which light can’t escape to infinity.”

If you define a black hole as a space-time with an event horizon then that is a correct statement. But then you will still have objects, let me call them “apparent black holes”, that look almost exactly like black holes for times that exceed the lifetime of the universe by several orders of magnitude. You will not, by any observation that is presently possible, be able to tell whether eg the center of the Milky Way harbors a black hole with event horizon or an apparent black hole that looks like a black hole with event horizon.

What Hawking is saying is essentially that he believes that a matter collapse only leads to a temporary apparent horizon but not to an eternal event horizon. That is an opinion which is shared by many of his colleagues (including me) and there is nothing new about this idea whatsoever.

It is very unfortunate that this statement by Hawking has been misinterpreted in this way because there are in fact people who claim that black holes don’t exist. They argue that what we observe are actually just very dark massive objects that never collapse beyond their Schwarzschild radius, but they do have a material surface. This is a fringe opinion to say the least, because it requires substantial changes to Einstein’s theory of gravity, not to mention that it’s in conflict with observation. I am very sure this is not what Hawking was referring to.

Having said that, Hawking’s “paper” is really just a writeup of a talk he gave last year. It’s mostly a summary of his thoughts on the black hole firewall, none of which I found very exciting or remarkable. Had this paper been posted by anybody else, nobody would have paid attention to it.

In summary, nothing has changed in our understanding of black holes due to Hawking’s paper. Move on, there’s nothing to see here.

Wednesday, January 29, 2014

A moment of silence replaces the big bang


“Big Bang” has become a household expression, but for physicists it’s primarily a Big Headache. Exactly what happened in the first moments of our universe is still not understood. In this early phase, when matter densities were extremely high, quantum fluctuations of space and time were large. We know that much, but we still do not know to describe these fluctuations which would require a quantum theory of gravity. Without that, we cannot reliably tell what banged, if anything.

It is generally expected that quantum gravity will remove the Big Bang singularity that general relativity predicts was the origin of our universe, but we don’t know with what it will be replaced. However, while we do not yet have a full theory of quantum gravity, different models for the early universe have been investigated. These are models based on, but not strictly speaking derived from, theoretical approaches to quantum gravity. The best known of these models are string cosmology and loop quantum cosmology, based on string theory and loop quantum gravity respectively.

Loop quantum cosmology in particular is well known for replacing the Big Bang with a “Big Bounce”: When the density of matter reaches a certain critical density (related to the Planck scale) contraction turns back into expansion. For a recent status update on string cosmology, see here.

A completely different approach to quantum gravity that we discussed recently is Causal Dynamical Triangulation which avoids singularities by discretizing space and time into chunks of finite size. In this approach it was recently found that space-time can exist in different phases, much like water exists in different phases. In the early universe, temperatures were high, and space-time might have been in a different phase, one in which space-time falls apart into causally disconnected pieces.

Phase diagram of space-time in CDT. See earlier post for details

It is thus very interesting that a similar behavior was recently found in loop quantum cosmology, an approach which a priori doesn’t have anything to do with Causal Dynamical Triangulation.

Jakub Mielczarek argues that the modification that arises through a loop-quantization of space-time can be rewritten in a suggestively simply way, as a density-dependence of the speed of light. A brief summary are these conference proceedings:

    J. Mielczarek,
    Asymptotic silence in loop quantum cosmology
    AIP Conf. Proc. 1514 (2012) 81, [arXiv:1212.3527].

The full length paper is here. It’s very technical, but the main conclusion is this: The higher the density, the slower the speed of light. At half the critical density, the speed of light reaches zero – this means points become causally disconnected. But things become even more interesting when the density becomes larger than half the critical density and increases towards the critical density. In this range the speed of light becomes an imaginary number and its square becomes negative. This means that time stops existing and turns into space. Physicists say space-time becomes Euclidean.

This finding realizes the so-called “no-boundary” proposal by Hartle and Hawking, and it also matches well with even earlier, quite general, considerations of what should happen nearby a singularity. In the classical theory, the causal disconnect happens only asymptotically and was dubbed ‘asymptotic silence’. In the quantized case, the causal disconnect happens at a finite time and replaces the singularity, and thus the big bang, by a singularity free region, a “moment of silence.”

I find this an intriguing development because here we have several different routes that point towards the same behavior at high density, much like is the case with dimensional reduction. I will not be surprised if further theoretical support for the moment of silence appears in the soon future. The big question is of course if traces of this silent beginning of the universe are left in observables like structure formation or the cosmic microwave background.

Monday, January 27, 2014

My invisible friend

Here's what I did on the weekend.

As you can see the video quality is still pretty crappy for reasons I can't figure out. Obviously I'm doing something wrong with the mixdown or the compression. To begin with, I probably shouldn't have combined the webcam recording with the rest. I was considerably more successful with the audio quality. Unfortunately, the microphone wouldn't speak to the camera, so I had to record the video and the audio separately and try to match them later, which is why the audio in some places seem out of synch. Sorry about that. I have a totally awesome microphone though and I'm very pleased with the audio. If you're not very careful with the microphone settings you can basically hear the neighbors fart in the recording.

If I find the time I'll do some more recordings and put a beat under this. I only noticed very belatedly that I accidentally mixed up G major with D major. So the piece is more, eh, interesting as it was supposed to be and I've violated the sacred law of amateurs #1: Learn the rules before you break them. Yes, it is clearly therapeutic to every once in a while engage in a project one doesn't know a thing about.

Wednesday, January 22, 2014

The science of the multiverse.

CMB aniotropies.
A new numerical study of bubble collisions makes a big step towards testing the multiverse hypothesis.

The multiverse might not be the most original or even surprising idea that physicists have proposed recently, but it certainly excelled in capturing the public imagination and in stirring up discussion. On the very top of the discussion list is the question whether the multiverse is a scientific idea at all, or whether it is simply a philosophical retreat for lazy physicists who’ve gotten tired hunting answers that didn’t come knocking on their door.

But there’s no simple answer to that question. Whether the multiverse is a scientific idea depends on what one means with multiverse. As I explained previously, the existence of “multiverses” in many theories is just a consequence of pushing models beyond their phenomenological reach. The only thing these types of multiverses demonstrate is that physicists don’t understand the limits of pure mathematics. In contrast, the best motivated multiverse is bubble universes in eternal inflation. And these can have observational consequences.

Eternal inflation is a variant of inflation, a phase of exponential growth in the early universe. Exactly how this phase proceeds depends on the properties of quantum fields that filled the universe back then. In eternal inflation, it is only parts of the whole space in which the rapid expansion comes to an end and structures like our galaxies form; these parts are referred to as “bubble universes”. In the rest of space, inflation continues and goes on to create new bubbles. This bubble production lasts eternally.

Most of these bubble universes are causally disconnected from ours and we have no chance to ever observe them. However, it is at least theoretically possible that some of these bubbles collide as they expand. This would mean that what is now our observable universe had, when we look back in time, not one seed, but two or more that later came to join. This type of bubble collision can have observable consequences for the formation of structures and leave imprints in the pattern of temperature fluctuations in the cosmic microwave background (CMB).

The accurate mathematical description of these bubble collisions is however difficult because Einstein’s field equations are non-linear. Solutions can normally only analytically be found in cases with many symmetries, and in the case of bubble collisions the geometry prevents one from using such a highly symmetric ansatz. Approximately valid analytical solutions have previously been put forward, but when one wants to make quantitative prediction one needs a sufficiently precise numerical simulation. Such a numerical simulation has to evolve forward in time the metric components, whose fluctuations eventually go to seed the perturbations in the CMB, which we then later measure.

Such a numerical simulation has recently been published in this paper
    Simulating the universe(s): from cosmic bubble collisions to cosmological observables with numerical relativity
    Carroll L. Wainwright, Matthew C. Johnson, Hiranya V. Peiris, Anthony Aguirre, Luis Lehner, Steven L. Liebling
    arXiv:1312.1357 [hep-th]
The authors only study the simplest case, that is the collision of only two bubbles and in addition these bubbles are identical (they have the same vacuum state). This is clearly not the most general case, but even so their simulation allows them to calculate the effects on the CMB better than previously possible.

Roughly speaking, the bubble collision leaves a localized temperature fluctuation - a hot spot or a cold spot - in the CMB that fades off away from the center of the collision. Exactly how it fades is very important for the extraction of such a signal from the data, and yet this could only be estimated before this numerical simulation was completed. Notably, the authors found that the fall-off is faster than was expected from the analytic estimates.

The figure below shows the time-evolution for the scalar field (Φ) that drives the inflation and two functions (a and α) that quantify the behavior of the metric. The horizontal axis is one of the spatial coordinates the vertical axes a measure for the time.

Figure 7 from arXiv:1312.1357 [hep-th]

What you can see in the image is how the configuration starts out being initially split in two halves and then evolves towards a situation where the initial split slowly fades away. That the bubbles both originate at “the same” time can always be achieved by a suitable choice of time-coordinate. The time, or the initial distances between the bubbles, can later be changed to a free parameter by a coordinate transformation.

This numerical study demonstrates nicely that it is possible to connect the underlying model for eternal inflation to observable signatures. It is also valuable in suggesting a useful parameterization for the effects. I find this a very interesting paper which will provide a basis for further studies that are necessary to analyze cosmological data for signals that might show we live in a multiverse.

Sunday, January 19, 2014

Trouble in the Ivory Tower: Not an academic problem.

The Ivory Tower.
Image from The Neverending Story.
“Science is the only news,” Stuart Brand told us. And the news is that research misconduct is on the rise while reproducible results are in decline. Peer review, the process in which scientific publications are evaluated by anonymous peers, has become a farce as scientists’ existential worries make it an exercise in forward defense with the occasional backhand offense. Scientists produce more papers now than ever, and then hide them behind journal subscriptions so costly nobody can read them – a good idea because most published research findings are probably false, though that too is probably false. Measures for scientific success have been criticized ever since they began being used, and the academic system chokes on social effects like herding, pluralistic ignorance and groupthink.

Yes, science works, no need to call me names. But science doesn’t work as good as it could, not as good as it should, not as good as we need it to work.

Scientific institutions and scientific management are stuck in the last century. The academic system today is in no shape to cope with the demands of high connectivity in a global and increasing workforce, is unable to deal with complex trans-national and interdisciplinary problems, and can’t handle the amplification of social feedback that information technology has brought.

The academic system, in brief, has the same problem as our political, social and economic systems.

The biggest challenge mankind faces today is not the development of some breakthrough technology. The biggest challenge is to create a society whose institutions integrate the knowledge that must precede any such technology, including knowledge about these institutions themselves. All of our big problems today speak of our failure, not to envision solutions, but to turn our ideas and knowledge into reality.

It’s not that we lack creativity. It’s that the kind of creativity that comes to us naturally does not latch upon problems evolution didn’t endow us to register to begin with. We do not comprehend the interplay of large crowds of people and are unable to individually beat our own psychology, rooted in groups of tens to hundreds, not billions. To arrange our living together in groups larger than we can intuit, we agree on rules of conduct and incentives that align our individual actions with collective trends so that both are to our benefit. This requires systems design. It requires science. And before that it requires we acknowledge the problem.

But we watch. We watch with bewilderment as a video of sunrise is broadcast on Tiananmen square where thick smog forces onlookers to wear breathing masks. We watch with horrified fascination video footages of the big garbage swirl and of birds dying from indigestible plastic pieces. We watch, hypnotized, replays of negotiation failures that make our adaptation to climate change more costly by the day. The way we have arranged, organized, policed and institutionalized our living together leaves us to watch ourselves watching, stunned at our own inability to change anything about it.

And scientists, the ones who should be able to analyze the situation and to devise a solution aren’t any better.

Scientists, of course, know exactly what is wrong with academia. Leaving aside that no two of them can agree on how to do it, they know how to solve the problem. There’s no shortage of proposals for how to fix peer review and scientific publishing and for how to better distribute resources. Futures markets, auction markets, lottery systems, open peer review, and dozens of alternative metrics have been suggested, we’ve seen it all. They write papers about it and send them for peer review. The rest is the same old he-said-she-said.

So far, scientists miserably failed to adapt the academic system to the changing demands of the 21st century. They belabor the problem and devise solutions, but are unable to implement them. And in the ocean of conference proceedings they watch the giant abstract swirl.

Academia mirrors the problem of our societies in a nutshell. The members of the academe, they’re all talk but no walk. We are being told that scientists are studying now the interconnectivity of the multi-layered networks that govern our societies, and we ask for answers and advice, we ask to be informed about how to solve our problems. There’s nobody else to solve these problems.

Social systems adapt to changing demands much like organisms do, by gradual modification and selection. But this process takes time – a lot of time – and it’s time we cannot afford. The only way to accelerate this adaption is the scientific method: a targeted, controlled, and recorded series of modifications. Many existing projects today aim to track and analyze the complex interactions of our highly interwoven networked world. But not a single one of these projects addresses the real problem, which is how to use this knowledge in the very systems that are being studied. It is this feedback of knowledge about the system back into the system that is necessary for our institutions to adapt. It requires a self-consistent scientific approach to institutional design, an approach that doesn’t exist and is nowhere near existence.

We need scientists to help us create social systems that organize our living together in groups so large that our evolutionary brains, trained to deal with small groups, cannot cope with. Trial and error will take too long and the errors are too costly now. But scientists are like the overweight doctor preaching the benefits of blood-pressure regulation, evidently unable to solve their own problems first. They presently can’t help us solve any problems, and we shouldn’t listen to their advice until they’ve solved their own problems.

Science is the only news, but it’s not only news. It’s the canary in the coal mine. Better watch it closely.

Wednesday, January 15, 2014

Loops vs Strings. Almost discovered for much longer.

I didn't attend this year's FQXi conference, but most of the talks will be uploaded sooner or later to the FQXi YouTube channel. The FQXi conferences always feature a mock debate with a role switch. I've never seen one with an actual exchange of arguments, but the debates have some amusement value. This year we have Carlo Rovelli defending String Theory ("You Loop people... insist that you cannot get any prediction from your theory. But we can't either.") and Raffael Bousso defending Loop Quantum Gravity ("What happened next was the string landscape. You've all heard of the string landscape. It's also known as 'The End of Science.'"). Enjoy.

Monday, January 13, 2014

Shooting strings

Shooting strings.
Source: Meez Forums.
String theory, once hailed as theory of everything, now struggles to demonstrate its use for anything at all.

Most string theorists today, if not working for banks, study the gauge-gravity correspondence. This celebrated idea, arguably one of the most interesting findings in string theory, relates a strongly coupled field theory in flat space to weakly coupled gravity in a higher dimensional space. These higher-dimensional spaces do not resemble our universe, so the interesting applications of the gauge-gravity correspondence are analytical calculations in strongly coupled field theory. Notoriously difficult problems of the field theory can become manageable by reformulating them in the language of gravity.

The most widely promoted use of this gauge-gravity correspondence has been the quark gluon plasma, which is produced in highly energetic collisions of heavy ions, previously at RHIC and now at the LHC. There has been a lot of hype about the low viscosity that was analytically found using the gauge-gravity correspondence and that fit well with observations. But heavy ion physics isn’t just viscosity. There are many other observables that a good model must be able to explain.

One of these observables is the energy loss that elementary particles experience when they travel through the plasma. Just by chance it can happen that a particle pair is created but only one of the two particles travels through the plasma and loses energy. The primary particles are unstable and eventually decay to form stable hadrons. By measuring and summing up the momentum of the decay products one can infer the energy loss that happened in the plasma.

We previously saw that the gauge-gravity correspondence seems to work well for the RHIC data, but misses the mark when the more recent LHC is also taken into account. The prediction is far outside the error margin of the data, both in terms of magnitude and in terms of slope. The gauge-gravity correspondence predicts too much energy loss. I call that a bad fit to the data. String theorists call it “qualitatively correct” which seems to mean their prediction has an upward slope.

But heavy ion physics is a messy business where many different processes come together and that makes it difficult to draw unambiguous conclusions. Clearly that situation doesn’t look good. However, as I mentioned earlier, last year I heard a talk by Steven Gubser about an upcoming paper of his addressing the energy loss in the gauge-gravity correspondence. Ficnar, Gubser and Gyulassy now recently posted their new paper on the arxiv:
    Shooting String Holography of Jet Quenching at RHIC and LHC
    Andrej Ficnar, Steven S. Gubser, Miklos Gyulassy
    arXiv:1311.6160 [hep-ph]

In this paper, the authors propose a new description on the gravity side for the particle which on the field theory side loses energy while traveling through the plasma. Previously, this particle was modeled by a string parallel to the boundary that fell towards the black hole horizon. Ficnar et al instead model the particle by a string that ‘shoots up’ away from the horizon. They calculate the energy loss of the endpoint and find that the energy loss is reduced relative to the previous scenario.

They do not motivate the gravitational description and I am left wondering if not there should be an unambiguous procedure to find the gravitational analogue. If one can just choose a different setup and get a different energy loss that does not exactly increase my faith in the predictive value of the model.

Be that as it may, with their new model a sufficient reduction of the energy loss can only be achieved by pushing the crucial parameter (λ, the ‘t Hooft coupling) into a limit where the approximation actually breaks down. This is no good because then the results cannot be trusted.

So then they add higher curvature terms on the gravity side. This introduces an additional parameter, and a suitable choice for this second parameter allows the coupling to remain just about in the okay range. One would expect these higher-order terms to be present, but in principle I’d think the coupling shouldn’t be an independent parameter. In any case, this still doesn’t fit both the RHIC and the LHC data.

Since the interpretation of the data depends on the reconstruction of the effective temperature at the collision, they then speculate that maybe the temperature values are off by 10% or so, in which case their calculation would fit the data just fine.

This model is clearly an improvement though I can’t say I am terribly convinced. What seems to become increasingly clear though is that any successful model for highly energetic heavy ion collisions must use a suitable combination of both weakly and strongly coupled physics. The gauge-gravity correspondence still has a good chance to prove its use for the strongly coupled physics, but that will necessitate getting into all the messy details.

Wednesday, January 08, 2014

Why quantize gravity?

When I first read DNLee’s story, I mistakenly thought “ofek” is a four letter word, an internet slang for oh-what-the-fucken-heck. Ofek, then, is all I have to say about my recent grant proposals being declined, one after the other. Ah, scrape the word “recent” – the Swedish Research Council hasn’t funded any one of my project proposals since I moved to Sweden in 2009. So all I can do is to continue to write papers as what feels like the only person working on quantum gravity in Northern Europe. Most painfully, I have had to turn away many a skilled and enthusiastic student wanting to work on quantum gravity phenomenology.

To add insult to injury, the Swedish Research Council publicly lists the titles of the winning proposals. You win if your research contains either “nano” or “neuro”, promises a cure for cancer, green energy, or a combination of the above. The strategy is designed for a bad return on investment. Money goes where lots of people poke the always same questions. If many flies circle the same spot there must be shit to find, the thinking is, let’s throw money at it. Our condensed matter people have no funding issues.

As nations face economic distress and support for basic research dwindles, why would anybody want to work on quantum gravity. Srsly. This question keeps coming back to me; its recurrence time conspicuously coincides with the funding agencies’ call cycles. It factors into my reflection index that women, I read, are drawn to occupations that help others, also occupations where they can use their allegedly superior social and language skills. What’ wrong with me? Why quantize gravity if I could cure cancer instead? Or at least write proposals promising I will, superior languages skills and all.

Modern medicine wouldn’t exist without the technologies that have become possible by breakthroughs in physics. There wouldn’t be any nano or neuro without imaging and manipulating quantum things and without understanding atoms and nucleons. Without basic research in physics, there wouldn’t be CT scans, there wouldn’t be NMR, nuclear power, digital cameras, and there wouldn’t be optical fibers for endovenous laser treatment.

At this point in history we still build on the new ground discovered by physicists a century ago. But the only way we can continue improving our circumstances of living is to increase our understanding of the fundamental laws of nature. And at the very top of the list there’s the question what is space and time, and how can we manipulate quantum objects. In my mind, these questions are intimately related. In my mind, that’s the ground the technologies of the next centuries will be built upon. In my mind, that’s how my occupation contributes to society – not to this generation maybe, but to the coming ones. Quantum gravity, quantum information, and the foundations of quantum mechanics are what will keep medicine advancing when nano and neuro has peaked and busted. Which will happen, inevitably, sooner or later.

So why quantum gravity? Because we know our knowledge of nature is incomplete. There must be more to find than we have found so far.

The search for quantum gravity is often portrayed as a search for unification. All other interactions besides gravity are quantized, there’s no unifying framework and that’s what physicists are looking for. It’s an argument from aesthetics, and it’s an argument I don’t like. Yes, it is unaesthetic to have gravity stand apart, but the reason we look for a quantum theory of gravity is much stronger than that: We know that unquantized gravity is incomplete and it is inconsistent with quantum theory. It isn’t only that we don’t know how to quantize gravity and that bugs us, we actually know that the combination of theories we presently have does not describe space and time at the fundamental level.

The strongest evidence for this inconsistency are the occurrence of singularities in unquantized gravity and the black hole information problem. The singularities are a sign that the unquantized theory breaks down and is incomplete. The black hole information problem shows that combining unquantized gravity with quantized matter is inconsistent – the result of combining them is incompatible with quantum theory.

Most importantly, we know that quantum particles can exist in superposition states, they can be neither here nor there. We also know that all particles carry energy and all energy creates a gravitational field. We thus know that the gravitational field of a superposition must exist, but we don’t know what it is. If the electron goes through both the left and the right slit, what happens to its gravitational field? Infuriatingly, nobody knows.

Nobody knows isn’t to say that nobody has an answer. Everybody seems to have an answer, the flies are circling happily. So I’ve made it my job to find out how we can ever know, which leads me to the question how to experimentally test quantum gravity. Without finding observational evidence, quantum gravity should be taught in the math or philosophy departments, not in the physics departments.

The irony is that quantum gravity phenomenology is as safe an investment as it gets in science. We know the theory must exist. We know that the only way it can be scientific is to make contact to observation. Quantum gravity phenomenology will become reality as surely as volcanic ash will drift over Central Europe again.

Every time I go down this road of self-doubts, I come out at the same place, which is right here in my office with my notepad and the books and the piles of papers. Quantum gravity is the next level of fundamental laws. The theory has to be connected to experiment. Quantum gravity is my contribution to the future of our societies and to help advance life on planet Earth. And, so I hope, space exploration, eventually. Because I really want ask those aliens a few things.

Today I talked to a professional photographer. Between the apertures and external flash settings and my attempt to produce a smile, I learned that he too has to write proposals for project funding. In his case, that’s portraits taken by a method which, I gather, isn’t presently widely used and not very popular with the Swedes. It’s neither nano nor neuro and it wasn’t funded.

Money is time, and time flies, and so in the end the most annoying part is all the waste of time that I could have used better than searching for pretty adjectives to decorate my proposals. Your tax money at work. Neuro-gravity anybody? Nano is also a four-letter word.

Saturday, January 04, 2014

Book review: “Free Radicals” by Michael Brooks

Free Radicals: The Secret Anarchy of Science
By Michael Brooks
Profile Books Ltd (2011)

“Free Radicals” is a selection of juicy bits from the history of science, telling stories about how scientists break and bend rules to push onward and forward, how they fight, cheat and lie to themselves and to others. The reader meets well-known scientists (mostly dead ones) who fudged data, ignored evidence, flirted their way to lab equipment, experimented on themselves or family members, took drugs, publicly ridiculed their colleagues, and wiggled their way out of controversy with rhetorical tricks.

The book is very enjoyable as a collection of anecdotes. It is fast flowing, does not drown the reader in historical, biographical or scientific details, and it is well-written without distracting from the content. (I’ve gotten really tired of authors who want to be terribly witty and can’t leave you alone for a single paragraph).

Michael Brooks tries to convince the reader that there is a lesson to be learned from these anecdotes, which is that science thrives only because of scientists behaving badly in one way or the other. He refers to this as the “secret anarchy of science”. He actually disagrees with himself on that, as it becomes very clear from his stories that far from being anarchic, science is an elitist meritocracy that grandfathers achievers and is biased against newcomers, in particular members of minorities. Anarchy is unstable – it’s a vacuum that gets rapidly filled with rules and hierarchies – and academia is full with these unwritten rules. Science is not and has never been anything like anarchic, neither secretly nor openly, though the house of science has arguably housed its share of rebels.

Worse than that misuse of the term ‘anarchy’ is that Brooks tries to construct his lesson from a small and hand-picked selection of examples and ignores the biggest part of science, which is business as usual. As we discussed in this earlier post, the question is not whether there are people who bent rules and were successful, but how many people bent rules and just wasted everybody’s time, a problem to which no thought is given in the book.

Luckily, Brooks does not elaborate on his lessons too much. The reader gets some of this in the beginning and then again in the end, where Brooks also uses the opportunity and tries to encourage scientists to engage more in policy making. Again he disagrees with himself. After he spent two hundred pages vividly depicting how scientists care about nothing but making progress on their research, arguing that this single-mindedness is the secret to scientific progress, in the last chapter he now wants scientists to engage more in politics, but that square block won’t fit through the round hole.

In summary, the book is a very enjoyable collection of anecdotes from the history of science. It would have benefitted if the author had refrained from trying to turn it into lessons about the sociology of science.

Thursday, January 02, 2014

10 Misconceptions about Free Will

If somebody talks about a “question that science cannot answer” what they really mean is a question they don’t want an answer to. Science can indeed be very disrespectful to people’s beliefs. I accept the wish to believe rather than know, but I get pissed off if somebody wraps their wishful thinking as an actual argument.

“Do humans have free will?” is a question I care deeply about. It lies at the heart of how we understand ourselves and arrange our living together. It also plays a central role for the foundations of quantum mechanics. In my darker moods I am convinced we’re not making any progress in quantum gravity because physicists aren’t able to abandon their belief in free will. And from the foundations of quantum mechanics the roadblock goes all the way up to neuroscience and politics.

Yes, I just blamed the missing rational discussion about free will for most of mankind’s problems, including quantum gravity.

Suggesting the absence of free will is apparently still an upsetter in the 21st century. You’re not supposed say it because allegedly just saying it makes other people immoral. Do you feel it already? How the immorality creeps from my blogpost into your veins? Aren’t you afraid to read on?

There’s no need to worry. This angst stems from a misunderstanding of what it means not to have free will. In this blogpost I address the most common misunderstandings, but before that let me explain why, to our best present knowledge of the laws of nature, you do not have free will. So, first the facts.

    Fact 1: Everything in the universe, including you and your brain, is composed of elementary particles. What these particles do is described by the fundamental laws of physics. Everything else follows from that, in principle.

    It follows in principle, but it is arguably not very practical to describe, say, human anatomy in terms of quarks and electrons. Instead, scientists of other disciplines use larger constituents and try to describe their behavior. This practical usefulness of increasingly larger scales, variables, and constituents, and the approximate accuracy of that procedure, is called “emergence”. All of these properties however derive from the fundamental description – in principle. That’s what is called reductionism.

    The idea that the emergent properties of large systems do not derive from the fundamental description is called “strong emergence”. Some people like to claim that just because a system (eg your brain) consists of many constituents it is somehow exempt from reductionism and something (free will) “strongly emerges”. But fact is, there exists no known example where this happens, and there exists no known theory – not even an untested one – for how strong emergence can work. It is entirely irrelevant if your large system has adjectives like open, chaotic, complex or self-aware. It’s still just a really large number of particles that obey the fundamental laws of nature. Presently, believing in strong emergence is on the same intellectual level as believing in an immortal soul or in ESP.

    Fact 2: All known fundamental laws of nature are either deterministic or random. To our best present knowledge, the universe evolves in a mixture of both, but just exactly how that mixture looks like will not be relevant in the following.

Having said that, I need to explain just exactly what I mean by the absence of free will:
    a) If your future decisions are determined by the past, you do not have free will.

    b) If your future decisions are random, meaning nothing can influence them, you do not have free will.

    c) If your decisions are any mixture of a) and b) you do not have free will either.
In the above, you can read “you” as “any subsystem of the universe”, the details don’t matter. It follows straight from Fact 1 and Fact 2 that according to the definition of the absence of free will in a), b), c) free will is incompatible with what we presently know about nature.

I acknowledge that there are other ways to define free will. Some people for example want to call a choice “free” if nobody else could have predicted it, but for what I am concerned this is just pseudo free will.

Right! I didn’t say anything about neurobiology, the consciousness or the subconsciousness or about people pushing buttons. I don’t have to. For free will to exist it is necessary that free will be allowed by the fundamental laws of physics. It is necessary, but not sufficient: If you could make free will compatible with the laws of physics, it might still be that neurobiology finds your brain can’t make use of that option. Physics cannot tell you that free will exists, but it can tell you that it doesn’t exist. And that’s what I just told you.

Note that I neither claim strong emergence does not exist, nor do I say that a fundamental law has to be a mixture of determinism and randomness. What I am saying is this: If you want to argue that free will exists because strong emergence works, or there is an escape from determinism or randomness, then I want to see an example for how this is supposed to work.

Then let me address the main misconceptions:

  1. If you do not have free will you cannot or do not have to make decisions.

    Regardless of whether you have free will or not, your brain performs evaluations and produces results and that’s what it means to make a decision. You cannot not make decisions. Just because your thought process is deterministic doesn’t mean the process doesn’t have to be executed in real time. The same is true if it has a random component.

    This misconception stems from a split-personality perspective: People picture themselves as trying to make a decision but being hindered by some evil free-will-defying law of nature. That is nonsense of course. You are whatever brain process works with whatever input you receive. If you don’t have free will, you’ve never had free will and so far you’ve lived just fine. You can continue to think the same way you’ve always thought. You’ll do that anyway.

  2. If you do not have free will you have no responsibility for your actions.

    This misconception also comes from the split-personality perspective. You are what makes the decisions (takes in information and processes it) and performs the actions (acts on the results). If your actions are problematic for other people, you are the source of the problem and they’ll take measures to solve that problem. It’s not like they have any choice… If the result of your brain processes makes other people’s lives difficult, it’s you who will be blamed, locked away, sent to psychotherapy or get kicked where it really hurts. It is entirely irrelevant that your faulty information processing was inscribed in the initial conditions of the universe, the relevant question is what your future will bring if others try to get rid of you. The word ‘responsibility’ is just a red herring because it’s both ill-defined and unnecessary.

  3. People should not be told they don’t have free will because that would undermine the rules of morally just societies.

    This misconception goes back to the first two and is based the idea that if people don’t have free will they don’t have any reason to reflect on their actions and to consider other people’s wellbeing. This is wrong of course. Evolution has endowed us with the ability to estimate the future impact of our actions and natural selection preferred those who acted so that others were supportive of their needs, or at least not outright aggressive towards them. If people don’t have free will they still have to make decisions and they still will be blamed for making other peoples’ lives miserable.

    Occasionally somebody refers me to this study which allegedly shows that “Encouraging a Belief in Determinism Increases Cheating.” This study also encourages misconception 2, so the finding is hardly surprising. I would like to see this repeated with the added explanation that the test subjects are of course still making decisions, regardless of whether the outcome was predetermined or not, and of course it matters what that outcome is.

  4. If you do not have free will your actions can be predicted.

    Even if your brain processes were predictable in principle it is highly questionable anybody could do this in practice. Besides, as I explained above, these processes might have a random component that is even in principle not predictable. It is presently not very well understood just exactly how relevant such a random component might be.

  5. If you do not have free will the future is determined by the past.

    Same misconception that underlies 4. Randomness is for all we presently know a component of the fundamental laws. In this case the future is not determined by the past, but neither do you have free will because nothing can influence this randomness.

  6. If we do not have free will we can derive human morals.

    I don’t know why people get so hung up on this. Morals and values are just thought patterns that humans use to make decisions. Their relevance stems from these thought patterns being shared by many in similar versions. If the fundamental laws of the universe are deterministic and if you were really good at computation, then you could in principle compute them. In practice nobody can do it.

    It is also not actually what people mean when they talk about ‘deriving morals’. What they actually mean is whether one can derive what humans “should do”. That however one can only do once a goal is defined – “should do” to achieve what? – and that just moves the question elsewere. Science can’t answer this question because it’s ill-defined. Science can’t tell what anybody should be doing because that’s a meaningless phrase. Science can, in the best case, just tell what they will be doing.

    More to the point is (as I explained in length in this earlier blogpost) that at any time there are questions that science cannot answer because the knowledge we have is insufficient. These are the questions we leave to political decision. All the “should do” questions are of this type.

  7. Free will is impossible.

    Not necessarily. As I explained here (paper here) it is possible to conceive of laws of nature that are neither deterministic nor random and that can plausibly be said to allow for free will. Alas, we do not presently have any evidence whatsoever that this is realized in nature and neither is it known whether this is even compatible with the laws of nature that we know. Send me a big enough paycheck and give me some years and I’ll find out.

  8. You need to be a neuroscientist to talk about free will.

    We associate free will with autonomous systems that make choices, with activation patterns in human brains, which is the realm of neurobiology. However, your brain as much as every other part of the universe obeys the fundamental laws of nature. That these fundamental laws allow for free will is a necessary condition for free will to exist, and these laws fall into the realm of physics.

  9. You need to be a philosopher to be allowed to talk about free will.

    If you want to know how everybody and their dog throughout the history of mankind defined free will, you had better read several thousand years’ worth of discussion on the issue. But I don’t like to waste time on definitions and I don’t see the merit in listing all variants of free will that somebody sometime has come up with. I told you above very clearly what I mean with ‘absence of free will’ and that is the core of the problem in two paragraphs. If you want to name this other than “free will”, I don’t care, it’s still the core of the problem.

  10. If we do not have free will we cannot do science.

    I added this misconception because this comes up every time I talk about superdeterminism in quantum mechanics. The basic reason we can do science is that our universe evolves so that we are able to extract regularities in that evolution. You need to be able to measure what happens to similar systems under similar conditions and find patterns in that. But just how these similar systems came about is entirely irrelevant. It does not matter, for example, whether the laboratory and all the detector settings were predetermined already at the beginning of the universe. All that matters is that there are similar systems, that detections can be done, and the results are processed by you (or some computer) to extract regularities.
Let me be very clear that I didn’t say free will doesn’t exist. I said it doesn’t exist according to our best present knowledge of how nature works. If you want to hang on to free will you better come up with a really good idea how to make that compatible with existing scientific knowledge. I want to see progress, I don’t just want to see smoke screens of “strong emergence” or “qualia” and other fantasies.