Natural Sciences

Understanding Natural Phenomena 8: The Ultimate Causes of Cosmic Order and Structure

Editor’s Note: This article is a part of the series Understanding Natural Phenomena.

What emerged at the Big Bang as a quantum fluctuation was an energy field, with no structure. But so much order and structure has emerged and evolved since then: Elementary particles, atoms, molecules, stars, galaxies, life, and so on. All this can be attributed to the following factors: the universe is expanding; the universe is cooling; the gravitational interaction was present right from the beginning; and ultra-minute quantum fluctuations occurred during the so-called ‘inflation‘ period, ~10-35 seconds after the birth of the universe. These fluctuations got amplified over time and were the original source of the cosmic structure we see today, including galaxies and clusters of galaxies.

Gradients of various types get created because of the expansion and the cooling of the universe. And these gradients are a measure of departure from equilibrium. The tendency to move towards equilibrium, so as to achieve stability, creates much of the order and structure. In addition, the inflation mentioned above was a one-off episode which created gradients, and its effects continue to affect the evolution of our universe.

I have already introduced the notion of free energy in Part 6. The second law of thermodynamics says that phenomena occur because their occurrence lowers the overall free energy. In particular, PHASE TRANSITIONS can occur for lowering the free energy. I consider the case of water to illustrate the notion of phase transitions. Above 100oC water exists as steam (at atmospheric pressure). Between 100oC and 0oC it exists as liquid water, and below 0oC it is ice. Thus there are three phases of water, namely steam, liquid water, and ice, each stable in an appropriate temperature (and pressure) regime. There is a change or transition of phase (or phase transition) from steam to liquid water on cooling to 100oC, because liquid water is more stable than steam below this temperature. Another phase transition occurs on cooling to 0oC, when liquid water changes to crystalline ice.

Let us begin at the beginning, and take a look at the figure below. It depicts the main events in the history of our universe. The time scale is not linear. The temperature rises as we go backwards in time towards the Big Bang, and physical processes happen more rapidly.

In the beginning the temperature was so high that no structure or order was possible, and there was only an energy field. As the very hot universe expanded after the cosmic explosion, it also cooled. 10-43 seconds after the Big Bang the temperature was ~1032 K (here K stands for ‘Kelvin’; 0oC = 273 K; no temperature can be equal to or lower than 0 K). The gravitational interaction was present at this stage.

The next important event in our cosmic history occurred 10-35 seconds after the Big Bang, and the technical term for it is INFLATION. During this very brief episode the rate of expansion of the newly born universe was much much higher than what it settled for after a while. In a way, it was this event which provided the real bang in the Big Bang.

As I said above, this inflation was one factor responsible for the later formation of structure in the universe. Why? The rate of expansion during the inflation was so very high that even the tiniest of quantum fluctuations got amplified and was enough for the nucleation and growth of structure. The temperature was ~1027 K, and matter (‘quarks’, ‘leptons’, ‘gauge bosons’, and several other elementary particles) appeared, as also ‘antimatter’. The appearance of matter and antimatter can be attributed to quantum fluctuations in the density of the universe, amplified by the effects of gravity. Even a miniscule increase in local density could attract more matter towards it, with a corresponding decrease in the surrounding density. That is how cosmic inhomogeneity arose and evolved.

At a certain stage of the inflation episode, a cosmic phase transition occurred, which freed enormous amounts of trapped energy (rather like the release of latent heat when steam condenses to water). After this prelude of inflation and cosmic phase transition, the normal (much slower) expansion of the universe set in, and has continued ever since.

During the inflation prelude, the universe grew extremely rapidly from a volume smaller than that of the nucleus of an atom to the size of a tennis ball. Why have cosmologists postulated the occurrence of inflation almost right after the Big Bang? With the postulation of the inflation episode certain cosmological mysteries get resolved. For example, when the universe was just the size of a tennis ball, regions that are very far apart today could have been in communicable contact then, resulting in the observed near-homogenization of the universe.

[Yes, the universe does look remarkably uniform or homogeneous in all directions (though not completely homogeneous). The present age of the universe is ~13.7 billion years. There are regions (e.g. the opposite sides of the horizon) that are so far apart that even light (the fastest moving signal anywhere) cannot travel from one end to the other in 13.7 billion years; so they cannot possibly be causally connected. But even they exhibit the same degree of homogeneity. This is known as the ‘horizon problem‘. The inflation hypothesis solves it.]

As you will see as we progress in this series of posts, an enormous number of facts about the evolution of order and complexity, as also the emergence and evolution of life, can be understood in terms of the following ultimate causes (in conjunction with the laws of quantum mechanics, relativity, and thermodynamics):

  • Expansion and cooling of the universe.
  • Emergence of the gravitational interaction at the birth of our universe.
  • Occurrence of the very rapid and brief cosmic inflation soon after the birth of the universe.
  • Occurrence and consolidation of quantum fluctuations during the inflation period.

About the author

Vinod Wadhawan

Dr. Vinod Wadhawan is a scientist, rationalist, author, and blogger. He has written books on ferroic materials, smart structures, complexity science, and symmetry. More information about him is available at his website. Since October 2011 he has been writing at The Vinod Wadhawan Blog, which celebrates the spirit of science and the scientific method.

5 Comments

  • Hi there, I have two questions regarding Big Bang theory, hope you will answer:

    1) Big Bang theory goes with a start of very hot state considered to be point, now I am unable to find what is the origin of that super hot state? Please answer.

    2) How can universe expands, something to expand need space like if a balloon is expanding it needs some space to expand, hope you are understanding what I meant to say?

    Please answer if you know. I hope you will answer..

    • Love, just wondering if you yourself have some pet answers to these questions or may be even an alternative to the big bang theory. If so please let us know.

    • The answers to your questions are already available in previous articles on this website.

      1. Please see Part 2 of this series for the answer to this part of your question: http://nirmukta.com/2012/04/06/understanding-natural-phenomena-2-the-big-bang/

      2. For the second part of your question, please see my article at
      http://nirmukta.com/2011/06/19/stephen-hawkings-grand-design-for-us/
      Here is an excerpt from it:
      ‘Suppose the beginning of the universe was like the South Pole of the Earth, with degrees of latitude playing the role of time. As one moves north, the circles of constant latitude, representing the size of the universe, would expand. The universe would start at a point at the South Pole, but the South Pole is much like any other point. To ask what happened before the beginning of the universe would become a meaningless question, because there is nothing south of the South Pole. In this picture spacetime has no boundary – the same laws of nature hold at the South Pole as in other places. In an analogous manner, when one combines the general theory of relativity with quantum theory, the question of what happened before the beginning of the universe is rendered meaningless.’

      This does not answer your question fully, and I shall give more details in a future post in this series. The main idea is that there is nothing outside the universe, and more and more space gets created as the universe expands.

  • Thank you for answering, I read all two links provided by you. There is nothing meaningless in science. There is always a reason behind it.
    I have thought this question from childhood. I hypothesized myself for these questions, May be I am right or may be I am wrong. I am posting my answers to these question here may be I am wrong or right.

    1)There is no such thing like creation or origin, something cannot create promptly. It should have something before that. As before matter there is energy. Matter and convertible to each other. They keep converting and producing new types of states.
    In the question, what was before very hot state. There can be another universe. The big Bang actually do not happened promptly within only one point. it can be by collision of two dyeing universes, which both concentrated on one point. These two universe collides and then the expansion begins. As we all know very well that our sun will die one day concentrating all his mass to one point. At that time it will engulf all planets. This dyeing sun or star have very large energy with minimum amount of mass and very large Gravity force. So universe never created from a point but it always created and destroyed and then again created by collision of two dyieng universes. i.e after death universe concentrated on one point and when there is collision between two points then creation and expansion of universe starts.

    2) How can universe expands because everything that expands need void or space to expand. Like if you heat up an iron rod it expands but you can expand an iron rod in tightly closed chamber. Same is applicable why there is space left on railway tracks, to provide them space to expand. So if universe is expanding it needs some void or space. This is explained by speed, natural forces, and energy changes the properties of time and space i.e these forces continuesly changes time and spaces and providing more space to universe so that it can expand. I normally give a simple example to define it: take a cloth which is tied by all corners tightly and note the distance between corner and middle point and then take a heavy ball and put ball in middle of cloth. Now measure the same distance between corner and middle, you will find the distance is shortened. because heavy ball make a rift in the middle. Weight of ball changes the distances between two points. Same is explained by Einstein to define future aircrafts which can change time and space, from the start point it can compress space and time and from the end point it can expand the time and space. Same is happening to expanding universe.

    May be I am wrong, I wrote to many physicts for this problem they replied the same as you. I am from biotechnology back ground so I am not able to prove this mathematically. If you agree with this or any other hypothesis you have then please tell me..

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