Lee Smolin Quotes

Unfortunately, so far... a truly background independent formulation of string theory has not been achieved... [It is] often called the search for M theory...

We show that some known classical results have particularly simple derivations within the Ashtekar formalism. These include Witten's positive energy theorem...

Calculation establishes that a quantum positive energy theorem may be possible using a representation based on the Ashtekar connection. Left open is a key question of whether this use of the Ashtekar connection is necessary or whether a positive quantum energy result can be achieved for representations based on other connections, i.e., for [other] values of the Immirzi parameter.

Some of the effects predicted by the theory [of loop quantum gravity] appear to be in conflict with one of the principles of Einstein's special theory of relativity... that the speed of light is a universal constant. ...Photons of higher energy travel slightly slower than low-energy photons. ...the principle of [general] relativity is preserved but Einstein's special theory of relativity requires modification. ...A photon can have an energy-dependent speed without violating the principle of [general] relativity!

There is no meaning to space that is independent of the relationships among real things of the world. ...Space is nothing apart from the things that exist. ...If we take out all the words we are not left with an empty sentence, we are left with nothing.

The suggestion was that a positive energy proof for general relativity could be gotten by restricting supergravity to its bosonic sector, which is general relativity.

In quantum theory, distance is inverse to energy, because you need particles of very high energy to probe very short distances. The inverse of the Planck energy is the Planck length.

Rule I: Except during a measurement, the wave evolves smoothly and deterministically, like a wave on water. ...
Rule II: During a measurement of position, the wave collapses around the position where it is seen, with a probability proportional to the square of the height of the wave, before the collapse. ...
In fact the two rules seem to contradict each other.

We seem to have an ingrained idea that if something is valuable, it exists outside of time.

Spacetime... turns out to be discrete, described by a structure called spin foam.

From the beginning of physics, there have been those who imagined they would be the last generation to face the unknown. Physics has always seemed to its practitioners to be almost complete. This complacency is shattered only during revolutions, when honest people are forced to admit that they don't know the basics.

Is the flow of time something real, or might our sense of time passing be just an illusion that hides the fact that what is real is only a vast collection of memories?

Jacob Bekenstein found... in 1971 that every black hole must have an entropy proportional to the area of its horizon... Stephen Hawking then refined this by showing that the constant of proportionality must be... exactly one quarter. ...entropy is supposed to correspond to a measure of information ...Loop quantum gravity... [gives] a detailed description of the microscopic structure of a black hole. ...a horizon can have, for each quantized unit of area, a finite number of states. Counting them, we get exactly Bekenstein's result...

One of the evident facts about the world is the stability of empty space-time. In classical general relativity we can explain this as a consequence of the positive energy theorem... the positive energy theorem must extend in some suitable form to any viable quantum theory of gravity.

We detect light and particles that have traveled billions of light years on their way across the universe to us. During the billions of years of travel, very small effects due to quantum gravity can be amplified to the point that we can detect them.