Human Perception Versus Physics: Which Is More Accurate? Which Is More Truthful?
What does a theoretical physicist do all day? Janna Levin shares some insight on perception vs. reality, and provides a glimpse of how she spends her time (hint: doing math).
Janna Levin is a professor of physics and astronomy at Barnard College of Columbia University. She is also director of sciences at Pioneer Works, a center for arts and sciences in Brooklyn, and has contributed to an understanding of black holes, the cosmology of extra dimensions, and gravitational waves in the shape of spacetime. Her previous books include How the Universe Got Its Spots and a novel, A Madman Dreams of Turing Machines, which won the PEN/Bingham Prize. She was recently named a Guggenheim fellow.
Janna Levin: Every human being models the world to understand it and that's cognitively how we're successful. So I don't look at a chair and see a huge number of molecules or some very complex structure, I see a chair. This is something that's very hard to teach a computer to do to understand conceptual things forward. And we conceptualize right away. We theorize right away. I have a theory of what that object is and my theory is that it's a chair. And that's what helps human beings be so adaptable in the world and so fast at moving through the world is precisely this ability to theorize and model. But we also know that by doing so we are projecting a theory of the world on the world and we trick ourselves, we deceive ourselves sometimes. The trick is to use the power that's given to us by being able to conceptualize and model and have metaphor, but always to remember that that's what we're doing and to always - when you come to a point there is in some sense no such thing as knowing something's true. It's true in the context of the model of the world that you have. And maybe there's a different model of the world where that truth is a little bit different. I mean I am in no position to talk about interpersonal relationships, but I think that this is a problem between people that we have a theory of the world and things mean the certain things in that context and we forget that somebody else has a different theory of the world and the exact same experience means something very different.
As a theoretical physicist I rely very much on calculating to understand a result. So let's say I want to know what happens when a big black hole swallows a little tiny black hole. My starting point will be to think what's my first mathematical sentence that I know if I crack it open will answer this question? Even with that step can be very hard. And then once I do that I'll be moving very in a very structured way through the steps to unlock that, but sometimes It's like a Rubik's Cube, which I'm actually not good at, some people can just solve it and some people just keep making a bigger mess. And so as a physicist you want your skill to improve to the point where you could just sort of unlock this thing. I find it very interesting when I work with much younger students I like to kind of sit back in the room when you we're calculating now and ask them to try to find the solution in a way that we do know how to go one step after another, but I'll be trying, at the same time, to try to find that cute way of unpacking it that's highly non obvious. And sometimes I'm sitting there for two days while they're generating 12 pages of very tough beautifully done calculations where I'm trying to find a way to try to do it in a half a page.
And sometimes I succeed and sometimes I don't. Sometimes I can't do that, it's just not possible or I haven't figured out how to do it. And sometimes I do. And when you do it's not just that it's shorter, it's that you're working with such bigger structures that you can see so much more at a time. I don't know how else to explain it. How chess players see a lot of the game at one time in one sort of thought they see many plays. It's also why I don't play chess because I see one play at a time. And I think that's the difference. It's not just that it's shorter, it's that in some sense you've seen many plays at a time. But in terms of the ambiguity, our calculations have to be exact. We can't be like I'm not really sure it's something like this. I mean there is an art to approximating, for sure, especially in astrophysics, but the kind of calculations I tend to do are very precise and there are no approximations and there's no skipped steps.
But that's not reality. So everything we've ever looked at in the universe is an approximation. We only know the number pi to some number of digits. We don't know every digit in pi, nor will we ever. And so in some sense pi can't be measured. It's an abstract thought, but it's not something that can ever exist in reality. When I tell you the mass of the electron I always have to end at some precision where I no longer know for sure what the numbers are that follow. And so in some sense in reality we never have the precision we have in the mathematics on the page. And that's an interesting ambiguity to think about. Do precise numbers exist in reality? Is there anything whose value is one? There isn't because the best we can do is say it's close to one at some precision that we've been able to observe.
One of humanity’s gifts is the ability to simplify. Instead of acknowledging millions of molecules creating structures strong enough to sit on, people just see a chair. People can look past underlying patterns of electricity and silicon, to see a computer. When looking at a crowd, most people aren’t hit with immediate wonder at the hundreds of individuals with unique lives and perspectives. Instead, it’s just a crowd, filled with bustling bodies and blurry faces. Humanity simplifies things in order to understand them.
We also are very accomplished at assigning things meaning, according to Janna Levin, a theoretical astrophysicist, and professor of physics and astronomy at Barnard College at Columbia University. Looking at a chair and seeing a chair is a distinctly human trait. Robots struggle with this – they see particles, lines, and shapes but not a direct meaning. This human habit is useful but often lands us into trouble. A chair is a chair to us, but we can’t assume that to be the truth of the object, it’s just the meaning we have assigned it. This becomes complicated when the item is not as objective. Different things have different contextual meaning to different people. Although Levin is an expert on particles, not people, she theorizes that humanity could benefit from remembering that meaning is entirely projected, and that we should be conscious of that fact in our daily life. The only truth that is reliable is that we can never really know what a truth is, even if 7 billion people agree on it, or if the disagreement splits the world in half. It’s humbling to remember and is helpful, even philosophically, in conflict resolution. Don’t assume that what you see is the only truth.
Levin is not just an accidental philosopher, but a very intentional mathematician. In her second point of this video, she explains her job as a theoretical physicist. She will work for days on end to find new ways of solving a problem she already knows the answer to, searching for new methods that will be more direct and efficient, and useful in later calculations. She explains that a normal linear math equation is like playing a step-by-step chess game, where each step is the whole focus. But a physicist tries to create a more succinct equation to do what a good chess player does: see the entire game before it happens. It’s truly fascinating to get a small glimpse at a day in the life of a physicist.
Janna Levin's most recent book is Black Hole Blues and Other Songs from Outer Space.
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