Everything Is The Way It Is Because We Are There To Ask This Question.
-One Line Explanation Of Anthropic Principle.
The first view of the universe was based on Ptolemy’s model, which had the Earth at the centre, of not only the Solar System, but also the Universe. This model reflected out mindset of wanting to be the centre of attraction, everything in this Universe was for us, it ‘revolved’ around us. As humans, we have developed our sense of perception, and immense knowledge, and this made us too proud of ourselves. Everything was created by God for us, and just us. The church accepted this model, because of the same reason, it showed us in the centre of the Universe and thus portrayed us as the important being created in God’s own vision.
This idea was vastly accepted and whosoever discredited it, paid a price, their life. But as our knowledge widened, with careful observations, and a bit of open-mindedness, people and the church(after much unwillingness) accepted a new model of the Universe: The Copernicus Cosmological Model. Nicolas Copernicus, after careful observation of the movements of the sun, and the stars introduced his model of the solar system with the Sun at the centre, and the Earth and other planets revolving around it. This was a big blow to our ego. Not only were we not the centre of the Solar System, later observations revealed we were neither the centre of the Milky way galaxy, nor the Universe. It was as if we were all just as normal as the other parts of the Universe. We might not be as important as we assumed ourselves to be. We did not hold a special place in the mind of God.
This idea met a lot of criticism for disobeying the picture of God represented by the Ptolemy Model, but slowly, and after great sacrifices by great philosophers, we accepted the truth. We were meagre. We moved on. But years later, one of the most important philosophical questions, brought us, or more correctly, intelligent life, back into the limelight. Observations for the speed of expansion of Universe revealed that the Universe was not only expanding, but accelerating. This meant, for now, it wasn’t going to stop expanding and start contracting under the influence of its own gravity, which was a shock. Scientists thus claimed for the existence of a repulsive force, to keep the Universe accelerating. The answer was Einstein’s biggest mistake (Or as he called it one), the cosmological constant. In short this is the average energy density of the Universe, and this energy is what keeps the Universe expanding. Before, scientists thought that this constant was unnecessary and should be zero, since Einstein added it forcefully to account for a static Universe, but calculations and the fact that Universe is accelerating, brought it back, with a value of ~ 3×10−122 in Plank units. It is in fact believed that the ‘Dark Energy’ is this diffused energy represented by the cosmological constant.
Now comes the bigger story. Scientists and philosophers began to question, why is the value of the cosmological constant so nearly zero, so much small, but still just right to allow for an expanding Universe. Which led to a bigger question: Why are the universal constants, what they are? Why is pi=3.141, or electron charge =1.6×10^-19 Coulombs, and so on? The answer to this question was equally philosophical in nature, and is called (deceptively) The Anthropic Principle. This principle was introduced by physicist Brandon Carter. He showed that the value of cosmological constant was so adapted to allow for the formation of the Universe that if had been of one order more, it would mean that the Universe expanded at a faster rate, which wont give atoms even time to form, they would be pulled apart, and if it had been less, the Universe would have started to contract into a ‘big crunch’. Extending this to other constants, he said that if they had not been what they were, Universe would have been much difference, and intelligent life, or life at all, wouldn’t be possible in such a Universe.
This was the basis of the Anthropic Principle, which says we might indeed hold a special place in the Universe(s). The Universe is what it is, because it supports life that can ask this very question. Had it not been this way, no life would emerge, and thus no one would be there to ask this question. It has two basic forms: the ‘weak’ form and the ‘strong’ form. The ‘weak’ form concerned the privileged position in space-time. It basically says that we are where we are in space and time, because these conditions are what best support life, and help an intelligent life form to evolve and ask this very question. If the Earth was closer to sun, it would be too hot to support life. Consecutively, we are here at this moment in time, because earlier the Universe was in infancy, too young to support any kind of formation of life, and later in time, the Universe will be ‘too dead’ to. All the perfect matching of time and position and other conditions of our position in space and time enabled life as we know to emerge in this planet. The ‘strong’ anthropic principle extends this theory to all the values of fundamental constants in physics, and says that if the values of these constants were any different, atoms wont form, galaxies wouldn’t exist, and life would be nowhere to be seen. The fact that the value of strong nuclear force is high enough to avoid the electromagnetic repulsions of the protons in the nucleus, and electromagnetic force enough to help electrons, protons and neutrons form atoms, is why all elements exist, galaxies formed, and along with the perfect conditions and our position in space time, gave birth to life on Earth.
Roger Penrose said about the Weak Anthropic Principle: “The argument can be used to explain why the conditions happen to be just right for the existence of (intelligent) life on the Earth at the present time. For if they were not just right, then we should not have found ourselves to be here now, but somewhere else, at some other appropriate time. This principle was used very effectively by Brandon Carter and Robert Dicke to resolve an issue that had puzzled physicists for a good many years. The issue concerned various striking numerical relations that are observed to hold between the physical constants (the gravitational constant, the mass of the proton, the age of the universe, etc.). A puzzling aspect of this was that some of the relations hold only at the present epoch in the Earth’s history, so we appear, coincidentally, to be living at a very special time (give or take a few million years!). This was later explained, by Carter and Dicke, by the fact that this epoch coincided with the lifetime of what are called main-sequence stars, such as the Sun. At any other epoch, so the argument ran, there would be no intelligent life around in order to measure the physical constants in question — so the coincidence had to hold, simply because there would be intelligent life around only at the particular time that the coincidence did hold!”
This was interpreted as ‘intelligent design’ by many. But the Anthropic Principle has a wider consequence. It actually predicts the existence of multiple universes or a multiverse. There exist many alternate universes, infinite actually (infinite space can have infinite number of objects), and all these Universes have different values of physical constants, some whose cosmological constant is too low, contracted before any galaxy or star could form, those whose cosmological constant is high, have expanded so fast that no atoms could form, some have a different value of electric charge than ours, which did not allow electrons to move around a nucleus, or form stable atoms. But many of these Universes, have the values of physical constants in the very thin domain of acceptable values, and these Universes support life to form. This life may be different, unlike ours which is based on carbon, theirs might have a different chemical make up depending on the conditions, but if life emerges in them, and evolves into an intelligent life form, they can ask the question, Why Is the Universe The Way It Is? And the answer will be, because if it weren’t you wont exist to ask that question.
The name Anthropic Principle is deceptive in nature. The term ‘Anthropic’ again puts Humans (as opposed to a possible intelligent in limelight), confusing some that the Universe is this way specially for ‘humans’ and no other life form. But this principle is Universal, and applies to every Universe that has just the right values for constants in physics to support life. Even though Copernican Model is true for our position not being central in the Universe, the fact that it is what it is just to allow us to exist, is something good enough to make us feel special(But as a whole living community, and not just humans). I am a firm supporter of this idea, are you? Share your thoughts below? Got something to add to this, or any suggestion? Comment below. Happy Reading!
-The Cosmogasmic Person