Albert Einstein is one of the greatest and certainly best known physicists. If you ask anyone to name a physicist the most common answer you will receive is “Einstein”.
Einstein is also famous for his quotations. Among the many Einstein’s quotations one is particularly popular among the general public: “God does not play dice”. But what did Einstein mean by this?
The quotation says, “Quantum theory yields much, but it hardly brings us close to the Old One’s secrets. I, in any case, am convinced He does not play dice with the universe.” It was addressed by Einstein to Max Born (one of the fathers of Quantum Mechanics) in a letter that he wrote to Born in 1926. The “Old one” and “He” Einstein refers to is God. The fame of this quotation stems from two sources:
1) Einstein’s disagreement with the fundamental concept of Quantum Mechanics that at the quantum (i.e. atomic) level nature and the universe are totally random, namely events happen by mere chance;
2) Einstein’s views about religion and God.
At first sight these two sources seem to be completely uncorrelated, not to say opposite, and many scientists and members of the general public will agree with this, but some other scientists and perhaps a portion of the general public will probably see a correlation between these two realms: science and religion.
Let us look at these two sources individually. Quantum Physics; we keep hearing these two words every now and again but what Quantum Physics is and how does it enter in the equation of our daily lives?
Quantum Physics is one of the pillars of modern physics and underpins most of the modern technology that makes our lives comfortable and enjoyable. For example, Quantum Physics is at the heart of transistors (little devices that make our mobile phones, laptops, tablets etc. work), nuclear power (e.g. nuclear reactors for the production of energy), magnetic-resonance imaging, or MRI, (one of the most largely used clinical instruments for the diagnosis of a large variety of pathologies and illnesses), lasers (monochromatic, i.e. only one colour, light sources used anywhere in our daily lives from DVD players and the scanner at the check-out points in stores, to industrial cutting and welding of materials and eye surgery for correction of short-sightedness) and so on. This very useful physical theory was developed in the 1920’s and allowed us to “see the invisible” (invisible as what we cannot see with our naked eyes or even by means of instruments), i.e. to explain the structure and physical properties of atoms (which make up all the matter including human beings) and molecules (ensembles of atoms; the most famous molecule is probably water formed by two atoms of hydrogen – H – and one atom of oxygen – O –: H2O), nuclear reactions (one product was, for example, the atomic bomb also called H-bomb because it worked by using the heat generated by a fission reaction to compress and ignite a hydrogen fusion), collision of particles inside accelerators (e.g. the Large Hadron Collider – LHC – at CERN in Geneva whose detectors ATLAS and CMS were able to find the Higgs Boson; LHC was also used to recreate the conditions that existed immediately soon after the Bing-Bang and, therefore, to try to understand what happened in the first instants of “life” of the universe), etc.
But if Quantum Physics is such a useful theory why did Einstein disagree with it? After all, Quantum Physics cannot predict events precisely (like the statistical theories that can be used to predict which number will come out when we throw dice). Quantum Physics is based on the notorious ‘Heisenberg’s Uncertainty Principle‘, which states that one cannot simultaneously measure the position and the momentum (i.e. the velocity that a particle can reach depending on its mass, with heavy particles that move fast having large momentum because it will take them a large or prolonged force to get up to speed and then again to stop them) of a particle. Just to give a practical example, if we think about the tiniest car possible (e.g. the nanocars, made of atoms, that are being developed in the nanotechnology sector), and we know the position of the car, we cannot know its momentum – whether it’s going fast or slow and vice versa. Nothing can be certain according to Quantum Physics. We can only predict how probable an event is to happen (like how many probabilities are there for six to come out when we throw dice). It was this uncertainty that Einstein disagreed with.
In his opinion every event and the physical properties of each individual particle can, and must be measured with high precision. Quantum physics does not allow for that; it tells you how probable it is for a system of particles to behave in a certain way but it will never tell you how each individual particle belonging to that system will behave.
Einstein could not accept this level of randomness and uncertainty in nature and the universe and he expressed his opinion in the sentence “God does not play dice”.
Here we come to the second source: Einstein’s view about religion. Much has been written and speculated about this point. Some people are convinced that Einstein was an atheist and others believe that Einstein was religious but not in the orthodox way. Einstein wrote a lot about science and religion, so why don’t we ask him?
Einstein was Jewish by birth and after a period of deep religiosity in his youth he did not practice Judaism. However, Einstein was not an atheist as he said himself in an interview in 1929. Einstein had his personal views about religion and he believed in what he called “cosmic religion” where God’s presence was evident in the order and rationality of nature and the universe in all its aspects and expressions. Chaos and randomness are, therefore, not part of nature (“God does not play dice”). According to Einstein, “cosmic religious feeling is the strongest and noblest motive for scientific research”. In his opinion, the goal of a scientist should be to try to begin to understand the universe. Einstein had a deep feeling of awe in front of nature and the universe and he believed that “strenuous intellectual work and the study of God’s Nature are the angels that will lead me through all the troubles of this life with consolation, strength, and uncompromising rigor” (letter to Pauline Winteler, 1897).