Lee Smolin quotes:

General relativity predicts that time ends inside black holes because the gravitational collapse squeezes matter to infinite density.

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.

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.

Just like an ordinary guitar string, a fundamental string can vibrate in different modes. And it is these different modes of vibration of the string that are understood in string theory as being the different elementary particles.

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.

Those who do good science do so because they choose problems that are suited to them.

The most cherished goal in physics, as in bad romance novels, is unification.

On the way, I shared the backseat of Feyerabend's little sports car with the inflatable raft he kept there in case an 8-point earthquake came while he was on the Bay Bridge.

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.

Surprise is inherent in the structure of the world.

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.

One possibility is: God is nothing but the power of the universe to organize itself.

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

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

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.

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

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.

Deep, persistent problems are never solved by accident; they are solved only by people who are obsessed with them and set out to solve them directly.

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.

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.

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

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.

There is nothing outside the universe

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.