The Quest for Unity

I have recently been reading Lee Smolin's fine book 'The Trouble with Physics'. Smolin is an influential theoretical physicist. In his book Smolin describes the history of physics as a process of unification. Smolin outlines three features that unifications tend to share. The features are (1) surprise, (2) new insights, and (3) new predictions that can be confirmed by experiment.

1) Surprise - Unification brings together things that had previously seemed distinct. The result is an 'aha' moment. What had previously seemed familiar becomes unfamiliar, discovery brings forth new uncertainty.

2) New Insights - When previously distinct assumptions are unified, the unfamiliar eyes through which we peer reveal a new landscape. A new vision of the world emerges, which may often be difficult for many to accept.

3) Novel Predictions (hypotheses)- New insights lead to new predicitions. From a scietific standpoint these new predictions must stand up to the scrutiny of experiment. Many beautiful hypotheses have failed this final hurdle. It is through the validation of experiment that explanatory power is confirmed and our uncertainty of the world can be reduced.

Smolin provides many fascinating examples. In the 16th century Giordan Bruno unified our sun with the distant stars.  His claim was not well recieved.   Smolin describes the dogma at the time:

 'the sun was a great fire created by God to warm the earth, while the stars were pinholes in the celestial sphere that let in the light of heaven'.

If Brunos idea (that our sun was just another star) were true there would be many implications. The stars would have to be much further away than previously thought. This would contradict the prevailing view, 'Heaven cannot be just overhead'. Bruno delivered this chilling qoute:

"I await your sentence with less fear than you pass it. The time will come when all will see what I see."

For his unifying idea Bruno was burned alive by the Catholic Church.

Also in the 16th century Nicolaus Copernicus unified the earth with the planets in our soloar system. This would have implications for understanding how objects move and come to be at rest in contradiction with Aristotle's theory. Earth had been seen as the center of the universe and the new proposal indicated it was just another planet. In the 17th century Galileo Galilei and Isaac Newton then unfied motion and rest with the princliple of inertia. Being at rest was now a special case of uniform motion. There was no absolute meaning to motion, it must now be considered relative to an observer. To explain this Galileo invented the principle of relativity. Smolin describes this type of discovery (the absolute instead being found to be relative) as the rarest and highest form of unification.

'When it is achieved it radically alters our view of the world'.

For supporting the views of Copernicus, Galileo was found guilty by the inquisition of heresey. By recanting he was allowed to live out his years under house arrest. Nevertheless the unifications kept coming. After many years of studying the motion of the planets and after several failed attempts Johannes Kepler was able to define three laws describing the manner in which the planets orbited the sun. His theory was able to make predictions that held true for each planet. Smolin describes how Keplers laws set the stage for Newton.

'It was Newton's great insight to see that the force the sun exerted on the planets is the same as the force of gravity that holds us on Earth, and hence to unfiy physics in the heavens with physics on Earth.'

 and

In the Newtonian revolution there were several proposed unifications that triumphed at once: the unification of the earth with the planets, the unification of the sun with the stars, the unification of rest and uniform motion, and the unification of the gravitational force on Earth with the force by which the sun influences a plant's motions.'

 In Smolins view it was the collective supportive force of theses ideas that allowed them to survive. The process of discovery through unification is progressive. Newton himself put it this way:

"If I have seen further it is by standing on the shoulders of giants."

It was not until the 19th century that the next great unfication was achieved. This occurred in the 1860's when James Maxwell Clerk unified electrcicty and magnetism. In the 1840's Michael Faraday had introduced the concept of a field and had worked with electric and magnetic fields. Maxwell was able to show mathematically that electric and magnetic fields transform back and forth between each other. Here is how Smolin describes it:

"These transmutations give rise to waves of shifting patterns, in which first there is an electric field and then a magnetic field, and which move through space"

 These waves carried energy and Maxwell discovered that they moved at the speed of light. The unification of electricity and magnetism had unexpectedly led to another great unification.

"The waves passing through electric and magnetic fields are light"

 With these new insights so rose new unceartanties. For hundreds of years it was accepted that everything was made of matter, as required by Newtons laws. Waves without substance traveling through space did not fit within this picture. In addition Maxwells theory also seemed to oppose the priciple of relativity. One of these accepted theory's would have to fall. Most physicist felt that the theory of a material universe had to stand. Albert Einstein however saw the principle of relativity as more fundamental.

Einstien was able to unfiy Maxwells theory of ectromagnetism with Galileo's principle of relativity.

"one observer might explain a particular phenomenon interms of electricity, while another observer moving relative to the first, would explain the same phenomenon in terms of magnetisim"

This became known as 'special relativity' and it also led to the unfication of space and time. Einstiens theory stood up to experiment where other theorys failed. It could no longer be taken for granted that the world was made up of matter. Einsteins next great unification began with the insight that the:

"effects of acceleration are indistinguishible from the effects of gravity." 

Uniform motion had previously been unfied but the motion of acceleration had remained separate. Now Einstein had unfied all of motion. What followed was Einsteins unification of space, time and gravity which became known as 'general relativity'. This was a dramatic change in how the physical world came to be seen. Space and time were no longer a fixed background. Space and time themselves are changing and evolving together. According to Smolin:

"Our whole notion of cosmology was turned on it's head"

Einsteins discoveries also helped bring forward the next great revolution in physics. This was quantum mechanics which Einstein could never fully accept. Quantum mechanics unified (sort of) waves and particles, energy and matter. The questions raised by this theory are still very much open for interpretation to this day. Quantum mechanics, although it is not fully understood makes un-erring predictions and led to the current standard model of particle physics. This model exlpains our world in terms of forces and particles on the smallest of scales. On this level it is unfied, yet it is contradicted by the gravity of Einsteins general theory of relativity. The two great theories of modern physics (general relativity and quantum physics) are thus in conflict.

This contradiction describes the biggest unkown question that physicists have been trying to unify for many years. String theory has been the dominant approach, but Smolins book describes this emphasis as a big misstep of physics.

Despite all the progress there remain other important physical unkowns in wait of unification which Smolin outlines five in his book.

Even if a theory of everything in physics were found there would be many other unifications to be bridged. How did life emerge from matter, and consciousness from life? Is there a way to connect physics to chemistry to biology to neuroscience, psychology, philosophy and the arts and humanities?

Ofcourse Bruno didn't really unify the sun and the stars and Einstein didn't really unify space, time and gravity. The sun shared it's properities with other stars long before Bruno, and ever since the big bang time space and gravity have been evolving together. What these men were able to do was to see the non-separability in what appeared to be separate. We stand on thier shoulders because what is familiar and accessible to us took curiosity, imagination, humility, perseverance, and special insight at the time of their discoveries.

In the centuries since the Newtonian revolution the disciplines of science and the humanities have become more specialized and separated from each other. Perhaps it is time to place more focus on synthesis across disciplines. This is not to denigrate the benefits of reductionism. It is my position that reductionsim and synthesis should complement each other.

What is it that may seem common and familiar  to us today, butt could become unfamiliar through a new unifiaction? What is it that may hold constant across the sciences and the humanities implying the promise to connect them?

There are some very interesting attempts at unification across  disciplines which I hope to post about soon.