Breaking the Mother of All Paradigms
“It is, I think, particularly in periods of acknowledged crisis that scientists have turned to philosophical analysis as a device for unlocking the riddles of their field. Scientists have not generally needed or wanted to be philosophers”
– Thomas Kuhn
It used to be used as a joke, but a well established string theorist, Erik Verlinde, is challenging the existence of gravity, calling it an “illusion” (no word as to whether he is willing to step out of a 95th floor window to test his hypothesis):
The New York Times (Dennis Overbye) – A Scientist Takes On Gravity
It’s hard to imagine a more fundamental and ubiquitous aspect of life on the Earth than gravity, from the moment you first took a step and fell on your diapered bottom to the slow terminal sagging of flesh and dreams.
But what if it’s all an illusion, a sort of cosmic frill, or a side effect of something else going on at deeper levels of reality?
So says Erik Verlinde, 48, a respected string theorist and professor of physics at the University of Amsterdam, whose contention that gravity is indeed an illusion has caused a continuing ruckus among physicists, or at least among those who profess to understand it. Reversing the logic of 300 years of science, he argued in a recent paper, titled “On the Origin of Gravity and the Laws of Newton,” that gravity is a consequence of the venerable laws of thermodynamics, which describe the behavior of heat and gases.
“For me gravity doesn’t exist,” said Dr. Verlinde, who was recently in the United States to explain himself. Not that he can’t fall down, but Dr. Verlinde is among a number of physicists who say that science has been looking at gravity the wrong way and that there is something more basic, from which gravity “emerges,” the way stock markets emerge from the collective behavior of individual investors or that elasticity emerges from the mechanics of atoms.
Looking at gravity from this angle, they say, could shed light on some of the vexing cosmic issues of the day, like the dark energy, a kind of anti-gravity that seems to be speeding up the expansion of the universe, or the dark matter that is supposedly needed to hold galaxies together.
….It goes something like this: your hair frizzles in the heat and humidity, because there are more ways for your hair to be curled than to be straight, and nature likes options. So it takes a force to pull hair straight and eliminate nature’s options. Forget curved space or the spooky attraction at a distance described by Isaac Newton‘s equations well enough to let us navigate the rings of Saturn, the force we call gravity is simply a byproduct of nature’s propensity to maximize disorder.
Some of the best physicists in the world say they don’t understand Dr. Verlinde’s paper, and many are outright skeptical. But some of those very same physicists say he has provided a fresh perspective on some of the deepest questions in science, namely why space, time and gravity exist at all – even if he has not yet answered them.
Dr. Verlinde goes into greater detail about his ideas on The Reference Frame, the blog of Czech string theory physicist Luboš Motl. It seems from the comment section that Dr. Motl is not buying it at all and is politely saying that Verlinde’s hypothesis is complete nonsense ( or, conversely, if true, is so revolutionary that Verlinde upends not only everything we know about physics, but also logic). Here is another expert commentary. Here I cordially invite some of my scientist readers, Shane, Dr. Von and Cheryl to weigh in as well.
Nevertheless, what Verlinde is doing, challenging the unchallenged paradigm, is intellectually very useful.
Sir Isaac Newton who explained gravity’s action did not know what gravity was. We still don’t know what it is even though physicists today have a much wider perspective than did Newton, whose discoveries were the bedrock of not just modern science, but modernity itself. When concepts are accepted blindly we tend to stop thinking of them very deeply. Not everyone, Stephen Hawking has spent a great deal of time pondering gravity as did Albert Einstein in his later years when he groped hopelessly for a unified field theory. Richard Feynman too, was a deep thinker on gravity:
Most of us unfortunately, including most physicists, are not Einstein, Feynman or Hawking.
The difficulty with theoretical physics and questions as fundamental to the order of nature as gravity is that we may be limited in our ability to understand the universe conceptually by the physical, biological, structure of our brains and the scalar level and time frame we inhabit. It is very hard to mentally see outside that box. Our brains can only entertain so many variables or so much complexity at one time and our conceptual imagination is largely influenced by sense perceptions. Mathematics helps us get around our physical limitations as does the processing speed of supercomputers but these crutches themselves refer back to the preferred cognitive avenues of our physical brains.
In thinking about fundamental or overarching phenomena, it is useful to pause and consider that as primates, we may not have been optimized by evolution to easily discern the most significant mechanisms of the physical world when our hominid deep ancestors eluded the apex predators of the Paleolithic Age. With great probability, Verlinde is spectacularly wrong here but his paper, because he is is a credible scientist with an impressive record, is forcing a lot of very smart people to stop and reasses what they know to be true in order to defend it from his heresy – cough…excuse me – his hypothesis 🙂
In doing so, some of them may gain insights of importance that otherwise never might have occurred. Insights that may only be tangentially related to Verlinde’s original idea.
Dissent is the grain of sand that can yield a pearl.
July 13th, 2010 at 7:34 am
Zen,
Verlinde’s premise is that gravity is an "entropic force" — a force not derived from the singular contribution of microscopic components (e.g., the mass of a particle) but rather from the statistical inclination of the whole system to increase its entropy. This is counter-intuitive since entropy is a macroscopic measure of microscopic *disorder*, yet we have empirical evidence of gravity creating macroscopic order from dust to stars, solar systems and galaxies.
I’ve scanned Verlinde’s paper, and find it curious that he trumpets his derivation of Newton’s Law of Universal Gravitation (albeit from a thermodynamic premise). Since we can observe the attractive force of gravity, it’s impossible to dispute the inverse-square relationship between mass and distance. In fact, Newton postulated his gravitational theory when he observed an apple fall from a tree (no, not onto his head) — and saw the moon rising behind the tree, leading him to wonder if the same force that pulled the apple to the ground was also at work on the moon.
As Einstein has shown, Newton’s laws are reasonable approximations — but not precise. Verlinde goes well beyond Newton’s "action at a distance" necessary for the Law of Universal Gravitation to work (an idea that made Newton uncomfortable), and conceives of space as simply an "information storage mechanism" with non-local information present in the form of entropy. He also postulates that the surface of an object (the "screen") contains all the information within that system, akin to the surface of an object emanating heat from within. While the "exchange of gravitons" idea for propagation of gravitational force seems as absurd as the notion (before 1000 A.D. and Ibn al-Haytham’s "Book of Optics" proved the intromission theory of vision) that something left the eye and then returned to tell the brain what it saw, Verlinde’s "paradigm shift" is to remove gravity from the list of fundamental forces — and with it, the notions of space and time.
While Einstein’s General Theory of Relativity treats gravity as a feature of curved spacetime (and not as a ‘force’), Verlinde wants to alter the very foundation upon which our physical sciences are built. This is where I have a problem with his heuristic approach: it’s one thing to derive equations from a different set of "first principles", but it’s entirely another to claim that this invalidates the basis from which those equations were originally derived.
The value of a model is manifest in its ability to predict and relate behaviors. We’ve done a pretty good job manipulating the physical universe with our present view of physics, so until Verlinde can extrapolate new phenomena from his model his ideas will be little more than Quixotic fixations to me.
July 13th, 2010 at 2:26 pm
Physicists have been wondering ever since how this “holographic principle” — that we are all maybe just shadows on a distant wall — applies to the universe and where it came from.
Didn’t Plato write something about shadows on the wall of a cave?
“I doubt whether these ideas will stand the test of time,”
If time is actually an illustion, then what difference would that make?
I’m no physicist, but it seems somebody has dropped the ball on this gravity thing.
July 13th, 2010 at 3:01 pm
Let’s see him reduce his claim to a testable hypothesis, build an experiment that tests it, then publish the results.
Anyone can challenge the fundamental paradigms that underlie modern science by typing. But that is not a real challenge, it is making stuff up.
Dr. Verlinde, let’s see it. If your right, bully for you, and let’s figure out how we can use the knowledge. If not, there is value in crossing it off.
July 13th, 2010 at 5:09 pm
gravity as an illusion? what fun! for the obverse is even truer in political and strategic matters: an attractive illusion operates like gravity, even warping our sense of space and time. . . ?
July 13th, 2010 at 10:27 pm
You know, I was actually thinking about this a couple days ago. I always wondered about an entropy angle to this, except with a slightly different take. Given that gravity bends space, couldn’t it be that this is all that gravity does? Just bends space? And then, this becomes kind of a path of least resistance, where in the course of moving from order to disorder matter naturally drifts along that least resistant path?
It’s been a while since I’ve read any books on the topic – have we settled whether gravity is field or force?
Full disclosure: I don’t know what I’m talking about.
July 13th, 2010 at 10:48 pm
Hi Mark – I have a truly wonderful proof of this, but this dialog box is not large enough to hold it.
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Seriously, I’m very busy this week and am not going to be able to give this much time. Maybe next week.
July 14th, 2010 at 2:08 am
Hey Zen,
Good thoughts by Shane, which constitutes much of what I would say, so no need to repeat. I also agree that it is a good thing for people to always question more established theories – heck, that is what Einstein did. I will need to look at the holographic principle in more detail, as that is something I never have dealt with, and will get some info from a former student, who is now a string theorist.
Obviously, being an experimentalist, when these types of papers come out there is one primary question that stands out above all others, and that is, OK, some nice math, but where is a testable prediction that is unique to your ideas? I have not read the entire paper yet, but there are some experiments that have been done and are being done, and more that are being planned, to test one of the predictions that come from Einstein’s field equations, and that is the notion of frame-dragging.
Schmedlap, in essence what Einstein’s general theory of relativity says is that matter bends space-time (technically the mass-energy density), and the hills and valleys of space-time for a topography that other objects follow. It is sort of like setting your cruise control and holding the steering wheel straight. The car drives straight, as far as you are concerned, but from another perspective you are moving on a curved path since the ground is curved because the earth is round. You have no choice but to follow the paths laid out by the hills and valleys of the earth’s surface. This is what objects, including massless photons (i.e. light), do moving through space-time. This is how Einstein explains gravitational effects…it is not a true force, as in Newton’s view, but instead a consequence of objects moving through warped space-time.
But for something to be ‘warped’ requires there is something physical to warp. Space-time should be a physical fabric of some sort. Frame-dragging is space-time being dragged when a massive object is moving through space, sort of like the wake formed by a boat moving through water. There are some inconclusive results of frame-dragging from a series of satellite experiments because error bars are still large (and the effect incredibly small….gravity is really weak). But all results have been consistent with predicted effects from Einstein’s theory. I want to understand how Verlinde’s model fits into the notion of a physical space-time fabric, for lack of a better term. This is the physical means of producing gravity in relativity, and does the holographic principle lead to the same ‘physicalness’ that is being tested?
At least this has a lot of people thinking about some interesting topics.
July 14th, 2010 at 5:13 am
Excellent comments! Special thanks to Shane and Von for their professional input and I look forward to Cheryl’s proof and continuing the discussion ( Verlinde, a theoretician, could use Cheryl’s help).
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David – strategy should be about attracting but it frequently is not ( maybe because most Americans confuse tactics with strategy). The "space" issue is very interesting -I’d say most would-be strategists going on offense underestimate the friction/costs imposed by space ( Hitler and Napoleon’s invasions of Russia come to mind)