UNIVERSE

THINK ABOUT NATURE

A Conversation with
[5.14.13]

Feynman once told me, "Whatever you do—you're going to have to do crazy things to think about quantum gravity—but whatever you do, think about nature. If you think about the properties of a mathematical equation, you're doing mathematics and you're not going to get back to nature. Whatever you do, have a question that an experiment could resolve at the front of your thinking." So I always try to do that.

 


TIME REBORN:
From the Crisis in Physics
to the Future of the Universe

 

LEE SMOLIN is a founding and senior faculty member at Perimeter Institute for Theoretical Physics in Waterloo, Canada. He is also Adjunct Professor of Physics at the University of Waterloo and is a member of the graduate faculty of the Department of Philosophy of the University of Toronto. His is the author od Time Reborn: From the Crisis in Physics to the Future of the Universe. Lee Smolin's Edge Bio Page

 


[58:16 minutes]

THE REALITY CLUB: Arnold Trehub, Sean Carroll, Lee Smolin, Bruce SterlingArnold Trehub, Amanda Gefter

 


THINK ABOUT NATURE

The main question I'm asking myself, the question that puts everything together, is how to do cosmology; how to make a theory of the universe as a whole system. This is said to be the golden age of cosmology and it is from an observational point of view, but from a theoretical point of view it's almost a disaster. It's crazy the kind of ideas that we find ourselves thinking about. And I find myself wanting to go back to basics—to basic ideas and basic principles—and understand how we describe the world in a physical theory.

What's the role of mathematics? Why does mathematics come into physics? What's the nature of time? These two things are very related since mathematical description is supposed to be outside of time. And I've come to a long evolution since the late 80's to a position, which is quite different from the ones that I had originally, and quite surprising even to me. But let me get to it bit by bit. Let me build up the questions and the problems that arise.

One way to start is what I call "physics in a box" or, theories of small isolated systems. The way we've learned to do this is to make an accounting or an itinerary—a listing of the possible states of a system. How can a possible system be? What are the possible configurations? What were the possible states? If it's a glass of Coca Cola, what are the possible positions and states of all the atoms in the glass? Once we know that, we ask, how do the states change? And the metaphor here—which comes from atomism that comes from Democritus and Lucretius—is that physics is nothing but atoms moving in a void and the atoms never change. The atoms have properties like mass and charge that never change in time. The void—which is space in the old days never changed in time—was fixed and they moved according to laws, which were originally given by or tried to be given by Descartes and Galileo, given by Newton much more successfully.

THINK ABOUT NATURE

Topic: 

  • UNIVERSE
https://vimeo.com/82413843

Feynman once told me, "Whatever you do—you're going to have to do crazy things to think about quantum gravity—but whatever you do, think about nature. If you think about the properties of a mathematical equation, you're doing mathematics and you're not going to get back to nature. Whatever you do, have a question that an experiment could resolve at the front of your thinking." So I always try to do that.

CONSTRUCTOR THEORY

A Conversation with
[10.22.12]

There's a notorious problem with defining information within physics, namely that on the one hand information is purely abstract, and the original theory of computation as developed by Alan Turing and others regarded computers and the information they manipulate purely abstractly as mathematical objects. Many mathematicians to this day don't realize that information is physical and that there is no such thing as an abstract computer. Only a physical object can compute things.

~ ~ ~ ~

I think it's important to regard science not as an enterprise for the purpose of making predictions, but as an enterprise for the purpose of discovering what the world is really like, what is really there, how it behaves and why.
 

DAVID DEUTSCH is a Physicist at the University of Oxford. His research in quantum physics has been influential and highly acclaimed. He is the author of The Beginning of Infinity and The Fabric of Reality. David Deutsch's Edge Bio Page

REALITY CLUB: Arnold Trehub, Harold Levey

CONSTRUCTOR THEORY

Topic: 

  • UNIVERSE
http://vimeo.com/83527852

There's a notorious problem with defining information within physics, namely that on the one hand information is purely abstract, and the original theory of computation as developed by Alan Turing and others regarded computers and the information they manipulate purely abstractly as mathematical objects. Many mathematicians to this day don't realize that information is physical and that there is no such thing as an abstract computer. Only a physical object can compute things.

~~

A BALLOON PRODUCING BALLOONS, PRODUCING BALLOONS:A BIG FRACTAL

[8.24.12]

Think about it this way: Previously, we thought that our universe was like a spherical balloon. In the new picture, it's like a balloon producing balloons, producing balloons. This is a big fractal. The Greeks were thinking about our universe as an ideal sphere, because this was the best image they had at their disposal. The 20th-century idea is a fractal, the beauty of a fractal. How many different types of these elements of fractals are there, which are irreducible to each other? The number will be exponentially large; in the simplest models, it is about 10 to the degree 10, to the degree 10, to the degree 7. It actually may be much more than that, even though nobody can see all of these universes at once.

ANDREI LINDE, a Russian-American theoretical physicist and professor of physics at Stanford University, is the father of "eternal chaotic inflation," one of the varieties of the inflationary multiverse theory, which proposes that the universe may consist of many universes with different properties. He is an inaugural winner of the $3 million Fundamental Physics Prize, awarded by the Milner Foundation. In 2002, he was awarded the Dirac Medal, along with Alan Guth of MIT and Paul Steinhardt of Princeton University. Andrei Linde's Edge Bio Page

A BALLOON PRODUCING BALLOONS, PRODUCING BALLOONS:A BIG FRACTAL

Topic: 

  • UNIVERSE
http://vimeo.com/80814823

Think about it this way: previously we thought that our universe was like a spherical balloon. In the new picture, it's like a balloon producing balloons, producing balloons. This is a big fractal. The Greeks were thinking about our universe as an ideal sphere, because this was the best image they had at their disposal. The 20th century idea is a fractal, the beauty of a fractal. Now, you have these fractals. We ask, how many different types of these elements of fractals are there, which are irreducible to each other?

Carlo Rovelli - Science Is Not About Certainty: A Philosophy Of Physics

Topic: 

  • UNIVERSE
https://vimeo.com/66561242

"I seem to be saying two things that contradict each other. On the one hand, we trust scientific knowledge, on the other hand, we are always ready to modify in-depth part of our conceptual structure about the world. But there is no contradiction, because the idea of a contradiction comes from what I see as the deepest misunderstanding about science: the idea that science is about certainty."

SCIENCE IS NOT ABOUT CERTAINTY: A PHILOSOPHY OF PHYSICS

[5.30.12]

I seem to be saying two things that contradict each other. On the one hand, we trust scientific knowledge, on the other hand, we are always ready to modify in-depth part of our conceptual structure about the world. But there is no contradiction, because the idea of a contradiction comes from what I see as the deepest misunderstanding about science: the idea that science is about certainty.                    

Introduction
by Lee Smolin 

Carlo Rovelli is a leading contributor to quantum gravity, who is also made influential proposals regarding the foundation of quantum mechanics and the nature of time. Shortly after receiving his Ph.D he did work which made him regarded as one of the three founders of the approach to quantum gravity called loop quantum gravity-the other two being Abhay Ashtekar and Lee Smolin. Over the last 25 years he has made numerous contributions to the field, the most important of which developed the spacetime approach to quantum gravity called spin foam models.These have culminated over the last five years in a series of discoveries which give strong evidence that loop quantum gravity provides a consistent and and plausible quantum theory of gravity.  

Rovelli's textbook, Quantum Gravity has been the main introduction to the field since its publication in 2004, and his research group in Marseille has been a major center for incubating and developing new talent in the field in Europe.Carlo Rovelli's approach to the foundations of quantum mechanics is called relational quantum theory, he also, with the mathematician Alain Connes, proposed a mechanism by which time could emerge from a timeless world called the thermal time hypothesis.

– Lee Smolin

CARLO ROVELLI is a theoretical physicist, working on quantum gravity and on foundations of spacetime physics. He is professor of physics at the University of the Mediterranean in Marseille, France and member of the Intitut Universitaire de France. He is the author of The First Scientist: Anaximander and His Legacy; and Quantum Gravity.

Carlo Rovelli's Edge Bio Page
Lee Smolin's Edge Bio Page

 

Thinking About the Universe on the Larger Scales

Topic: 

  • UNIVERSE
http://vimeo.com/79330250

"Andrei Linde had some ideas, Alan Guth had some ideas, Alex Vilenkin had some ideas.  I thought I was coming in with this radically new idea that we shouldn't think of the universe as existing on this global scale that no one observer can actually see, that it's actually important to think about what can happen in the causally connected region to one observer, what can you do in any experiment that doesn't actually conflict with the laws of physics, and require superluminal propagation, that we have to ask questions in a way that conform to the laws of physics if we want to get sensible a

Thinking About the Universe on the Larger Scales

[11.22.11]

Andrei Linde had some ideas, Alan Guth had some ideas, Alex Vilenkin had some ideas.  I thought I was coming in with this radically new idea that we shouldn't think of the universe as existing on this global scale that no one observer can actually see, that it's actually important to think about what can happen in the causally connected region to one observer, what can you do in any experiment that doesn't actually conflict with the laws of physics, and require superluminal propagation, that we have to ask questions in a way that conform to the laws of physics if we want to get sensible answers.

Introduction 

by Leonard Susskind

The parable of the blind men and elephant is a perfect metaphor for the universe and for the physicists who try to grasp its larger shape: each man feels a part of the elephant and tries to visualize its overall essence: "It's a wall"; "It's a rope"; "a tree": they almost come to blows. The universe, even more than the elephant, is too big for any one perspective, and most of us are busy squabbling about some small part.

Fortunately, now and then someone comes along who is brave enough, bold enough, and with clear enough vision, to have a chance of seeing the bigger picture. Raphael Bousso is one of those few.

— Leonard Susskind

RAPHAEL BOUSSO, Professor of Physics at the University of California, Berkeley, is recognized for discovering the general relation between the curved geometry of space-time and its information content, known as the "covariant entropy bound." This allowed for a precise and general formulation of the holographic principle, which is believed to underlie the unification of quantum theory and Einstein's theory of gravity. Bousso is also one of the discoverers of the landscape of string theory, which explains the small but non-vanishing value of the cosmological constant (or "dark energy"). His work has led to a novel view of cosmology, the multiverse of string theory. 

Raphael Bousso's Edge Bio page

LEONARD SUSSKIND, Felix Bloch Professor in theoretical physics at Stanford University, whose contributions to physics include the discovery of string theory. His most recent book is The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics.

Leonard Susskind's Edge Bio page

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