Old Physics and New Physics

I’ve mentioned before that one of the great pleasures of working in high-energy physics is its international nature. I find the diversity of people and cultures I encounter in the pursuit of knowledge exciting and refreshing.  This week I am visiting the famous Weizmann Institute of Science, outside of Tel Aviv. Many of the physicists in my field who are here or at nearby institutions were in the United States as students, as postdoctoral researchers, or as visitors, at places where I myself was working at one point or another.  Even one of my former students is here.  So there are many old friends and former collaborators in both string theory and particle physics for me to meet with, and to learn from. I’ll also be giving a couple of scientific lectures during this visit.

Meanwhile,  I wanted to mention a mildly interesting article that I happened to notice:


I have nothing negative to say about people doing research into exactly what babies do and don’t have intuition for at various ages, but there are two things I find problematic about the spin that is put on this story.

First, what is striking to me about human babies is not how much they know, but how little, and that point often gets lost in articles whose authors are impressed by how clever babies are. Watch a foal [= a baby horse, for my non-English-speaking readers] stand an hour after birth, and you can see how much intuitive physical understanding most animals are born with. It’s not surprising; they’d die pretty quickly without it.

Meanwhile, the other problem with this story is that knowing that things fall is not in any sense the same thing as knowing about gravity as a law of nature.  On the one hand, every mildly intelligent animal “knows” that things fall (e.g. acorns from trees, balls thrown into the air) except, of course, that birds don’t, and leaves on a windy day often don’t, but hey, who’s counting. And everybody “knows” that lightweight things  (leaves, sheets of paper) fall more slowly than heavy things (rocks, coconuts), though unfortunately this intuition, which everyone has from a young age, happens to be wrong.  As Galileo showed easily, and as you yourself can check easily by putting a coin (or even a small sheet of paper, if you are careful to lay it very flat) on the back of a heavy book and dropping the book, all things fall at the same rate as long as there isn’t air resistance to confuse you. A law of nature is not just a general regularity, such as “things fall”; it is something much deeper, much more precise, and much more subtle than that.

The same goes for solids and liquids; we may recognize that there are objects that prevent our bodies from passing through them, and others that do not, but in what sense is that understanding anything about them?   It’s a statement of “fact”; but facts, even general facts, are not laws.  They are consequences of laws, but they do not by themselves reveal the nature of the law.

What is really at play in the studies of babies’ intuition is that there are some very simple and basic principles of how to interact with the world that you must know if you are to live to the age of three. If you can’t figure out that things fall, you will probably suffer a deadly fall yourself; and if you can’t figure out that there are solids and liquids, you will hurt yourself running into a tree trunk or drown trying to walk across a lake.  You’d also better know quickly that you won’t be able to see in a dark place, and that the leopard that wants to eat you isn’t necessarily gone just because it has disappeared from view.   I’m sorry to say, however, that essential as these survival skills are, they do not count toward a degree in physics.

12 responses to “Old Physics and New Physics

  1. We are born barges in a narrow canal.

  2. Interesting article on baby learning, thanks. Ironically, part of the interest is that it seems to have a problem distinguishing between the concepts “intuitive” and “innate”, core of the “nurture” versus “nature” debate.

    When an animal learns something, that something is not innate. By definition. Even the foal stumbling around in his hour of need, is obviously learning. Learning fast, but still learning. Otherwise he would just stand up right away, without trying. The more one looks carefully, the more pure instincts are hard to find. Even a baby learns to feed. That, I found out, is a problem with breast feeding: far from being just an instinct, as I expected, it’s also an art. It can take hours, even days, to be mastered, by mother, and child.

    “Facts” are the elements of the set of all what is true. And what of the distinction between “fact” and law? A “law” is an axiom for physics. It is a fact, but a special fact. A set of all physical laws has to generate all facts.

    “Gravity as a law of nature”, as we have it now, explains the facts involving gravity that babies observe. But it goes only that far. If a child asks: and why does the earth attracts the moon? And we keep on evoking spacetime geodesics and the principle of inertia… I don’t believe we will sound very convincing (why is there inertia, already?)

    Why would we sound unconvincing to a particularly inquisitive child? Because we need not just to explain the world, but that this is the only world that could be (a duty that the multiverse partisans are trying to eschew).

    Actually we would be unable to find physical laws explaining why the floating rocks of the movie “Avatar” are really completely impossible. In truth, we do not know. “Unobserved so far” is different from “impossible from the physical laws we have”.

    As long as the set of physical laws we have not only explain all observed facts, but also excludes the rest, we cannot rest on our laurels. Indeed, this shows that we do not have an optimal set of physical laws (it’s like the distinction between “filter” and “ultrafilter” in topology). All we have is a tentative set of physical laws.

  3. “I have nothing negative to say about people doing research into exactly what babies…”

    You are too polite, the spin is terrible, the science is terrible and the whole thing stinks of dubious research and wasted money.

    If someone is truly interested in understanding human conscienceless, there is no better path than one’s own mind. However, it does not lead to publications, grants or news flashes.

    An old proverb: “The one who talks, does not know, the one who knows does not talk”.

    There is a vast knowledge that can be acquired by inquisitive mind about itself but its very nature precludes sharing. The process could be very scientific, but on strictly individual basis, everybody has to do it on their own. Silly studies of babies or baboons are of no use to those in search of who they really are.

  4. von Flöerkeputz

    did as well in lumosity test as would be expected from a baby

  5. My kids used to do experiments with gravity by throwing food all over the floor. They quickly discovered that cheerios and string beans fell at the same rate. Galileo would have been proud.

    But all this talk of “intuitive understanding of certain physical laws” because they could track hidden objects or suspect something would fall, and of “rudimentary math abilities” because they choose the plate with more food…well, let’s not start handing out Nobel prizes to every 10-month old just yet.

    I generally choose the plate with more food and it has nothing to do with math…

    I agree that understanding cognition levels in developing humans is interesting and fundamentally important, but the labels, the spin, is just a bit much.

    Tim Barzyk

  6. I have often pondered whether or not our “intuitive understanding of physical laws,” while admittedly important for survival, has not stood sentry between what we think we know and what we might know. The deeper physical laws are often counter-intuitive. Intuition may be overrated since even a baby can apparently intuit.

  7. Perhaps we could learn a thing or two from the innocence of babies. We come to the subject of gravity with a good deal of predudice – not the least of which is Einstein’s General Relativity (GR). Often, when food, toys, or whatever is placed before a baby in a high-chair, he will push it off the tray and down it goes. He will do this over and over, seeming to test gravity on everything you put in front of him. Simple as this is, mankind has completely failed in this regard. Since the discovery of the antiproton in 1955 (same year Einstein died) there has been speculation that antimatter might repel matter gravitationally. Yet in over 50 years, an experiment to determine the gravitational acceleration of antimatter has never been done. We are so cock sure of GR that all attempts to test the gravitational acceleration of antimatter have failed – due to lack of funding! The fact is that most physicists consider such an experiment to be a complete waste of time and money. Pretty cocky for a species that admits it only understands 4% of the Universe.

  8. Hi Matt,

    “Watch a foal [= a baby horse, for my non-English-speaking readers] stand an hour after birth, and you can see how much intuitive physical understanding most animals are born with.”

    Yes for sure seeing this in one of my own from the past there is definitely this drive to get up. But lets say you want to affect the horses behavior for when it is much larger. Let it believe that your are very capable of picking it up at let’s say 800lbs, then for sure you interrupt that cycle of animistic behavior and imprint by lifting it when it is a foal.

    “I’m sorry to say, however, that essential as these survival skills are, they do not count toward a degree in physics.”

    As layman I am sure those of us who recognize this will never believe more then what you are saying. It does not mean we cannot delve into the different concepts that one’s mathematics has been voiced from sciences lips to the wider audience. So on one level you have the mathematics that you express as concepts and how accurate are these concepts when tied to that math. The laws. People are listening.

    The public is trusting and in your hands. A lot of science is specialized and for that matter scientists too who have not ventured across the lines of their specializations yet they come equip with seeing the world in the way they have been trained in their science? That gives them unique perspective about looking at different aspects of life, economics ( https://lh6.googleusercontent.com/-q0yZDTevG40/RhzvdDadw3I/AAAAAAAAAfA/OPqt50Wl3G0/s234/bumble_bee4.jpg ), and their everyday life. Yes?

    The questions about the article then can further spark further questions indeed of what Innatism( http://en.wikipedia.org/wiki/Innatism ) is, what is a blank slate( http://en.wikipedia.org/wiki/The_Blank_Slate )and the Tabula rasa ( http://en.wikipedia.org/wiki/Tabula_rasa ).

    So this is not about metaphysics then, but a real question about what we are capable of doing? About our not being afraid to learn?

    Not all of the public can have their teachers. As students, can we find “the teacher within us” with which to move ourselves forward? How can we adapt to learning in the day and age of the internet? The distance physically to these higher institutions of learning is great for some, yet, the student in them without age or limitation can find what they are looking for?

    The scientist trained, occupyng a different trade until an opening comes up for them?


  9. Very good comments, Matt. A problem with some of these behavioral researchers is that they’re studying how kids and people learn about XY but the researchers don’t really understand XY themselves! Then it’s pretty hard, or pretentious, for them to place themselves “above” the subjects they pretend to study.