Lee Smolin Quotes

I first began to worry about this during the summer of 1989, when it began to be clear that string theory would not quickly lead to a unique theory of everything. Henry Tye, a string theorist from Cornell University, had told me of his computer program to produce new string theories. When you run Tye's program, you input a rough description of a universe you would like to describe. You tell it the dimension of spacetime, and something about how the world should look. It outputs all the string theories it can construct that lead to the world you requested, one per page.

Science is not about what's true. It's about what people with originally diverse viewpoints can be forced to believe by way of public evidence.

Any two particles in the universe attract each other through the gravitational interaction.

We know no more than we did in 1975 - and that's not good

Science moves fastest when there's plenty of debate and controversy.

When we human beings hypothesize that a law of nature holds - even temporarily or situationally - we are creating an idea, but we are also making a hypothesis about how nature behaves, whose truth or usefulness has nothing to do with what we know or believe.

A successful unification of quantum theory and relativity would necessarily be a theory of the universe as a whole. It would tell us, as Aristotle and Newton did before, what space and time are, what the cosmos is, what things are made of, and what kind of laws those things obey. Such a theory will bring about a radical shift - a revolution - in our understanding of what nature is. It must also have wide repercussions, and will likely bring about, or contribute to, a shift in our understanding of ourselves and our relationship to the rest of the universe.

Expressed in Planck units, the temperature T of a black hole is inversely proportional to its mass, m. This is a third law, Hawking's law: T = k/m. The constant k is very small in normal units. As a result, astrophysical black holes have temperatures of a very small fractionnof a degree.

Copernicus, 1996). Julian

So, Einstein's theory of gravity is a theory of causal structure. It tells us that the essence of spacetime is causal structure and that the motion of matter is a consequence of alterations in the network of causal relations. What is left out from the notion of causal structure is any measure of quantity or scale.

Indeed, as string theory was understood better, it became clear that the gauge interactions naturally emerged from it. But even more than this, during their period of exile from the mainstream, the string theorists realized that their theory naturally gave rise to an interaction that had all of the hallmarks of the gravitational force. In order to get the force to come out with the right strength, all they had to do was fix the length of the string to be about the Planck length. Thus, string theory had the potential to unify all of physics in a simple framework, in which all phenomena arise from the motion and vibrations of fundamental one-dimensional strings.

The page of my notebook was filled with many messy integrals, but all of a sudden I saw emerge a formula for counting. I had begun to calculate a quantity on the assumption that the result was a real number, but found instead that, in certain units, all the possible answers would be integers. This meant that areas and volumes cannot take any value, but come in multiples of fixed units.

We are very used to imagining that we see a three-dimensional world when we look around ourselves. But is this really true? If we keep in mind that what we see is the result of photons impinging on our eyes, it is possible to imagine our view of the world in quite a different way. Look around and imagine that you see each object as a consequence of photons having just travelled from it to you. Each object you see is the result of a process by which information travelled to you in the shape of a collection of photons. The farther away the object is, the longer it took the photons to travel to you. So when you look around you do not see space-instead, you are looking back through the history of the universe. What you are seeing is a slice through the history of the world. Everything you see is a bit of information brought to you by a process which is a small part of that history.

Simplicity and beauty are the signs not of truth but of a well-constructed approximate model of a limited domain of phenomena.

Because string theory is such a high-risk venture - unsupported by experiment,

Science is not about what's true or what might be true, science is about what people with originally diverse viewpoints can be forced to believe by the weight of public evidence.

Without having navigated waters shallow enough for us to see bottom, we'll be easy prey to mystifiers who want to sell us radical metaphysical fantasies in the guise of science.

Both loop quantum gravity and string theory assert that there is an atomic structure to space. In the next two chapters we shall see that loop quantum gravity in fact gives a rather detailed picture of that atomic structure. The picture of the atomic structure one gets from string theory is presently incomplete but, as we shall see in Chapter 11, it is still impossible in string theory to avoid the conclusion that there must be an atomic structure to space and time. In Chapter 13 we shall discover that both pictures of the atomic structure of space can be used to explain the entropy and temperature of black holes.

Some of its proponents like to say that string theory is a piece of twenty-first- century mathematics that has, by our good fortune, fallen into our hands in the twentieth century.

In the one real, time-drenched universe, everything has a particular history precisely because it is finite, and not part of an infinite array. Moreover, the cosmological use of the infinite serves to mask the failure of a physical theory taken beyond the boundaries of its proper domain of application. The most notable instance is the inference in contemporary cosmology of an infinite initial singularity from the field equations of general relativity. Finally, the admission of the mathematical infinite into natural science effaces the difference, which we emphasize, between nature and mathematics. Nature works in time, with which mathematics has trouble. Mathematics offers, among other things, the infinite, which nature abhors.

Good ideas are not taken seriously enough when they come from people of low status in the academic world; conversely, the ideas of high-status people are often taken too seriously.

A singularity is a point or region in spacetime at which some physical quantity such as the density of mass or energy, the temperature, or the strength of the gravitational field, becomes infinite. Whenever they happen, they pose serious difficulties for physics because they signal a breakdown in the description of the world in mathematical terms.

The fact that the amount of missing information depends on the area of the boundary of the trapped region is a very important clue.

Do you want a revolution in science? Do what businesspeople do when they want a technological revolution: Just change the rules a bit. Let in a few revolutionaries. Make the hierarchy a bit flatter, to give the young people more scope and freedom. Create some opportunities for high-risk/high-payoff people, so as to balance the huge investment you made in low-risk, incremental science. The technology companies and investment banks use this strategy. Why not try it in academia? The payoff could be discovering how the universe works.

The geometry of a universe is very like the grammatical structure of a sentence. Just as a sentence has no structure and no existence apart from the relationships between the words, space has no existence apart from the relationships that hold between the things in the universe. If you change a sentence by taking some words out, or changing their order, its grammatical structure changes. Similarly, the geometry of space changes when the things in the universe change their relationships to one another.

But in spite of the obvious effectiveness of mathematics in physics, I have never heard of a good a prioriargument that the world must be organised to mathematical principles.

if physics is much simpler to describe under the assumption that space is discrete, rather than continuous, is not this fact itself a strong argument for space being discrete? If so, then might space look, on some very small scale, something like Wilson's lattice.

How we think about the future and the past determines everything about how we think about our situation as human beings.

Newton's concept of space was the opposite, for he understood space to be absolute. This means atoms are defined by where they are in space but space is in no way affected by the motion of atoms. In a relational world, there are no such asymmetries. Things are defined by their relationships. Individuals exist, and they may be partly autonomous, but their possibilities are determined by the network of relationships. Individuals encounter and perceive one another through the links that connect them within the network, and the networks are dynamic and ever evolving.

Whatever is real in our universe is real in a moment of time, which is one of a succession of moments. The past was real but is no longer real. We can, however, interpret and analyze the past, because we find evidence of past processes in the present. The future does not yet exist and is therefore open. We can reasonably infer some predictions, but we cannot predict the future completely. Indeed, the future can produce phenomena that are genuinely novel, in the sense that no knowledge of the past could have anticipated them. Nothing transcends time, not even the laws of nature. Laws are not timeless. Like everything else, they are features of the present, and they can evolve over time.

But what is equally important, and sobering, is how often we fool ourselves. And we fool ourselves not only individually but en masse. The tendency of a group of human beings to quickly come to believe something that its individual members will later see as obviously false is truly amazing. Some of the worst tragedies of the last century happened because well-meaning people fell for easy solutions proposed by bad leaders.

It can no longer be maintained that the properties of any one thing in the universe are independent of the existence or non-existence of everything else. It is, at last, no longer sensible to speak of a universe with only one thing in it.

The revolution which began with the creation of quantum theory and relativity theory can only be finished with their unification into a single theory that can give us a single, comprehensive picture of nature.

Having begun my life in science searching for the equation beyond time, I now believe that the deepest secret of the universe is that its essence rests in how it unfolds moment by moment in time.

There certainly is a tension between the relativity of simultaneity and non-locality in quantum theory, but it's not strong enough to add up to a falsification of either side by itself.

Space and time emerge from the laws rather than providing an arena in which things happen.

there is nothing real or true that is timeless

Although it is hard to visualize a landscape in a space of high dimensions, the more the number of parameters, the more likely it is that a walk of any finite distance, taken in a random direction from a place near the summit of a mountain, will go down rather than up. Thus, we may conclude that, if the hypotheses made here are true, most changes in the parameters of the laws of physics will decrease the rate at which black holes are produced in our universe. Because of this, the theory I am sketching here is actually subject to observational test.

If a surface can be seen as a kind of channel through which information flows from one region of space to another, then the area of the surface is a measure of its capacity to transmit information. This is very suggestive.

We know that the expansion of our universe is accelerating, which means a number called the cosmological constant must be positive.

Time is described only in terms of change in the network of relationships that describes space. This means that it is absurd in general relativity to speak of a universe in which nothing happens. Time is nothing but a measure of change-it has no other meaning. Neither space nor time has any existence outside the system of evolving relationships that comprises the universe. Physicists refer to this feature of general relativity as background independence. By this we mean that there is no fixed background, or stage, that remains fixed for all time. In contrast, a theory such as Newtonian mechanics or electromagmetism is background dependent because it assumes that there exists a fixed, unchanging background that provides the ultimate answer to all questions about where and when.

On a personal level, to think in time is to accept the uncertainty of life as the necessary price of being alive. To rebel against the precariousness of life, to reject uncertainty, to adopt a zero tolerance to risk, to imagine that life can be organized to completely eliminate danger, is to think outside time. To be human is to live suspended between danger and opportunity.

If string theory is a mistake, it's not a trivial mistake. It's a deep mistake and therefore kind of worthy.

What we have, in fact, is not a theory at all but a large collection of approximate calculations, together with a web of conjectures that, if true, point to the existence of a theory.

There was a sense that the one true theory had been discovered. Nothing else was important or worth thinking about. Seminars devoted to string theory sprang up at many of the major universities and research institutes. At Harvard, the string theory seminar was called the Postmodern Physics seminar.
This appellation was not meant ironically.

Some string theorists prefer to believe that string theory is too arcane to be understood by human beings, rather than consider the possibility that it might just be wrong.

Every string theory that's been written down says the speed of light is universal. But other ideas about quantum gravity predict the speed of light has actually increased.