Wednesday, November 11, 2009

The Origin of the Universe and the Arrow of Time

Professor Sean Carroll, Caltech

Monday 16th November 2009
6 pm - 6.50 pm with discussion 6.50 pm - 7.30 pm
Eastern Avenue Auditorium, The University of Sydney
All welcome, admission free

One of the most obvious facts about the universe is that the past is different from the future. The world around us is full of irreversible processes: we can turn an egg into an omelet, but can't turn an omelet into an egg. Physicists have codified this difference into the Second Law of Thermodynamics: the entropy of a closed system always increases with time. But why? The ultimate explanation is to be found in cosmology: special conditions in the early universe are responsible for the arrow of time. I will talk about the nature of time, the origin of entropy and how what happened before the Big Bang might be responsible for the arrow of time we observe today.

Sean Carroll
is a theoretical physicist at the California Institute of Technology. He received his Ph.D. in 1993 from Harvard University and has previously worked at MIT, the Institute for Theoretical Physics at the University of California, Santa Barbara, and the University of Chicago. His research ranges over a number of topics in theoretical physics, focusing on cosmology, particle physics and general relativity. He is the author of From Eternity to Here, a popular book on cosmology and the arrow of time; Spacetime and Geometry, a textbook on general relativity; and has produced a set of introductory lectures for The Teaching Company entitled Dark Matter and Dark Energy: The Dark Side of the Universe. Carroll is a co-founder of the popular science blog Cosmic Variance ( He was recently awarded the 2009 Viktor Hamburger Outstanding Educator award. He lives in Los Angeles with his wife, writer Jennifer Ouellette.

This event is jointly sponsored by the University of Sydney’s Centre for the Human Aspects of Science and Technology (CHAST), the Centre for Time and the Sydney Centre for the Foundations of Science, and supported by the Australian Institute for High Energy Physics (AUSHEP).


  1. The Jocaxian Nothingness [Nada Jocaxiano]
    João Carlos Holland de Barcellos
    translated by Debora Policastro

    The “Jocaxian Nothingness” (JN) is the “Nothingness” that exists. It is a physical system devoid not only of physical elements and physical laws, but also of rules of any kind.

    In order to understand and intuit JN as an “existent nothingness”, we can mentally build it as follows: we withdraw all the matter, energy and the field they generate from the universe. Then we can withdraw dark energy and dark matter. What is left is something that is not the nonexistent. Let us continue our mental experiment and suppress elements of the universe: now, we withdraw physical laws and spatial dimensions. If we do not forget to withdraw anything, what is left is a JN: an existent nothingness.

    JN is different from the Nothingness we generally think of. The commonly believed nothingness, which we might call “Trivial Nothingness” to distinguish it from the JN, is something from which nothing can arise, that is, the “Trivial Nothing” follows a rule: “Nothing can happen”. Thus, the “Trivial Nothingness”, the nothingness people generally think of when talking about “nothingness”, is not the simpler possible nothingness, it has at least one restriction rule.

    Jocax did not define the JN as something in which nothing exists. Such definition is dubious and contains some contradictions as: “If in the nothingness nothing exists, then, nothingness itself does not exist”. No. First, Jocax defined what it means to exist: “Something exists when its properties are fulfilled within reality”. Therefore, JN has been defined as something that:

    1- Has no physical elements of any kind (particles, energy, space, etc.)

    2- Has no laws (no rules of any kind).

    Being so, JN could have physically existed. JN is a construction that differs from the “trivial nothingness” since it does not contain the rule “Nothing can happen”. That way, Jocax liberates his JN from semantic paradoxes like: “If it exists, then it does not exist” and claims that this nothingness is SOMETHING that could have existed. That is, JN is the simpler possible physical structure, something like the minimal state of nature. And also the natural candidate for the origin of the universe.

  2. We must not confuse the definition of the NJ with rules to be followed. It is only the declaration of a state. If nature is in the state defined by conditions 1 and 2 above, we say it is a “Jocaxian-Nothingness”. The state of a system is something that can change, differently from the rule that must be followed by the system (otherwise it would not be a rule). For example, the state “has no physical elements”; it is a state, not a rule because, occasionally this state may change. If it was a rule it could not change (unless another rule eliminated the first one).

    Being free of any elements, JN does not presume the existence of any existing thing but its own and, by the “Occam’s Razor” [2], it must be the simplest state possible of nature, therefore with no need for explanations about its origin. JN, of course, does not currently exist, but may have existed in a distant past. That is, JN would be the universe itself – defined as a set of all existing things – in its minimal state. Thus we can also say the Universe (being a JN) has always existed.

    JN, as well as everything that can be understood by means of logic, must follow the tautology: “it may or may NOT happen”. This tautology – absolute logical truth – as we shall see, has also a semantic value in JN: it allows things to happen (or not).

    We cannot say that events in the JN must necessarily occur. Eventually, it is possible that nothing really happens, that is, JN may continue “indefinitely” (time does not exist in a JN) without changing its initial state and with no occurrences. But there is a possibility that random phenomena can derive from this absolute nothingness. This conclusion comes logically from the analysis of a system without premises: as JN, by definition, does not have laws, it can be shaped as a logical system without premises.

    We shall interrupt a little in order to open up an explanatory digression. We are dealing with two types of “Jocaxian-Nothingness”: the physical object named “JN”, which was the universe in its minimal state with the properties described above; and the theory which analyses this object, the JN-Theory. The JN-Theory, the theory about the JN-object (this text), uses logical rules to help us understand the JN-Object. But JN-object itself does not follow logical rules, once there are no laws it must obey. Nevertheless, I do not believe we will let possibilities to JN-object escape if we analyze it according to classic logic. However, we must be aware that this logical analysis (JN-Theory) could maybe limit some potentiality of JN-Object.

    Within a system without premises, we cannot conclude that something cannot happen. There are no laws from which we can draw this conclusion. That is, there is no prohibition for anything to happen. If there is no prohibition for anything to happen, then, eventually, something may happen. That is, the tautological logics remain true in a system without premises: “something happens or not”. If something occasionally happens, this something must not obey rules and, therefore, would be totally random and unpredictable.