Philosophy of Cosmology Summer School

Going on right now, up at UC Santa Cruz — I guess the official name is the UCSC Institute for the Philosophy of Cosmology. It’s a three-week event, with talks by some top-notch people: David Albert, David Wallace, Tim Maudlin, Joel Primack, Anthony Aguirre, Matt Johnson, Leonard Susskind, and a bunch more. To my great regret I can’t be there for the whole thing, but I will be popping in during the last week to say some things about cosmology and the arrow of time. (Is it possible that not everything worth saying will have already been said?)

If you’re not actually there, they seem to be doing a great job of putting lectures on YouTube almost as soon as they appear. Almost like being there, except that you won’t get to walk outside into the redwood forest.

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15 Responses to Philosophy of Cosmology Summer School

  1. Gizelle Janine says:

    One question science wont answer: Why does David Albert look the best in a green shirt and pants made for a 30 year old? I guess some things just are… 😀

  2. Dan says:

    Thanks for the link. I can feel my brain shifting uncomfortably already.

  3. JLS says:


    I recently came across the work of a Dr. Hajdukovic developing the idea of gravitational repulsion between matter and anti-matter particles, and possible solutions for “dark matter,” “dark energy,” and big-bang cosmology that result from this hypothesis. (Papers can be accessed here:

    Dr. Hajdukovic clearly states that these ideas are still in the early stages of development, but I wanted to know if you have given his research any consideration? In particular, I was impressed with how the unexplained phenomenon mentioned above seem to develop naturally from the “simple” premise of gravitational repulsion between matter and anti-matter particles (and the resulting interactions of Baryonic matter with the quantum vacuum), and wanted to know if you or others in the community had a similar reaction?

  4. Thomas Walsh says:

    The basic question seems to be: is the universal law of gravitation unqualified? Could anti-matter have negative gravitational energy? Could gravity be an absolute related to all mass, a property of anti-matter or, perhaps, a non annihilation interaction of mater and anti-mater? After all, how much was known about anti-mater in 1916? Is the universe really overwhelming mater? Is the gravitational constant, big G, a variable dependent on physical processes, sometimes slow and sometimes faster, taking place over time? In this regard, the Neutron is composite particle that from scattering experiments has three reflection points. Could the Neutron be seen as composed of a Proton, an Electron and a Positron (there Quarks is the usual thinking)? If so, then there is far more anti-matter, although still small, in our daily world. A crazy idea, but could gravity in our world be dependent on Neutrons in atoms? If so, there is no mutual gravitational attraction between neutral Hydrogen atoms but there is a attraction between neutral Hydrogen and Hydrogen isotopes. This may seem crack pot; however, it could be tested – perhaps even today or in the near future. There are some visible observations that may make this seem less bizarre. Here is a recent one:

    Perhaps there are already experiments that prove this impossible (as opposed to a calculation or an extrapolation). Also, perhaps there are ‘failed’ experiments that are really great successes?

  5. Meh says:

    the nature of statistical mechanical probabilities! I wish the earth was an additional 37,400,000 km from the sun. If that sounds stupid; in my defense, the Maipenrai Pinot Noir is fantastic.

  6. Vladimir Chang-Tanaka says:

    @T. Walsh
    “This may seem crackpot.”
    Actually, dude, this IS crackpot, no question about it!
    “… could gravity in our world be dependent on Neutrons in atoms?”
    Or, more scathingly, could gravity even be dependent on quarks in atoms? As we all know, atomic theory is basically quark theory, because there are so many kinds of them, such as up, down, charmed, purple, magenta, puce, etc. That’s why quark theory is called quantum chromodynamics because “chromo-,” as all cosmologists know, is the Greek/Sumerian/Quechua root of the alveolar fricative meaning “color” which, as Meh has semi-surreptitiously pointed out, gives the Maipenrai Pinot Noir its vaunted “Hugh” (as in Jackman). Some connasewers also believe that it’s a secret essential ingredient of the famed Rombauer Chardonnay as well.

  7. HICKS says:

    Thank your for this careful reading and pertinent comment.
    According to Article II of the Chemical Weapons Convention, a CW is defined, together or separately, as
    (a) Toxic chemicals and their precursors, except where intended for purposes not prohibited under this Convention, as long as the types and quantities are consistent with such purposes;
    (b) Munitions and devices, specifically designed to cause death or other harm through the toxic properties of those toxic chemicals specified in subparagraph (a), which would be released as a result of the employment of such munitions and devices;
    (c) Any equipment specifically designed for use directly in connection with the employment of munitions and devices specified in subparagraph (b).

  8. Thomas Walsh says:

    Is the universal law of gravity unqualified for all forms mass? Another reason for questioning the unqualified nature of the law of gravity, is the variability of measuring G. For over a century and with many experiments, G has varied ~ +/- 1.5%. The Neutron is composed of 3 quarks and the Proton is also composed of 3 quarks. The Proton, unlike the Neutron, is not considered a composite particle. Scattering experiments show the Neutron with three points of reflections. Thus, the Anti-neutrino decay particle, cannot be one of the points. I wonder if the quark model hides subtle distinctions for the nature of the Neutron? If the gravitational attraction, neutral Hydrogen atom to neutral Hydrogen atom, is not measured, should we just assume that it is gravitationally the same as any other atom? The Hydrogen atom is not unique in the periodic table? Of course, you may well be correct and there is no difference. Anyway, this crackpot nonetheless does appreciate the reply and your bothering to read my questioning.

  9. Brendan says:

    Hi Sean,

    I’m a student at UCSC. I’d love to hear your talk. Is it closed to undergraduates?

  10. Sean Carroll says:

    Brendan– I believe the school is only for registered participants (I know some applicants were turned away). But everything should be on video.

  11. Alejandro says:

    Hello Sean,

    Your talks on this track are my introduction to you and I find them very exciting. I was looking for a book that may or may not exist that discusses your points in further detail. It appears as though you have not written one. Please let me know if one is in the works or if I just missed it.


  12. Sean Carroll says:

    Alejandro– My book “From Eternity to Here” is about these issues.

  13. Vladimir Chang-Tanaka says:

    @T. Walsh
    “Is the universal law of gravity unqualified for all forms of mass?”
    Yes, it is, & I’m glad you asked this question. As mentioned earlier, quantum chromodynamics has a large no. of colors, giving rise to a plethora of phantasmagorical chromatazomes, thereby contributing such other quarks as the taup quark (not to be confused with the top quark, a different kettle of fish), the cyan quark, the teal quark & of course the buff quark (check out the pecs on those buff quarks – impressive!).

  14. Thomas Walsh says:

    I think you are correct about QCD. If I believe the universal law of gravity is not unqualified (the uncertainties make it seem like a physical process), then gravity must be modeled within QCD itself – just think!

  15. John S. Hardy, M.D. says:

    I would appreciate a comment on the following hypothesis:
    From the “beginning” (pre-big bang), we surmise that the initial pre-big bang “environment” was “NON-existent” (i.e., a true vacuum) wherein there was NO extant space-time (and therefore no entropy nor chaos: I.e. a “null” environment), which contrasted with the potential of infinite space-time with limits determined only as they have thus (now) become.
    The evolving universe was therefore a closed system (event horizon) of enormous potential.
    If Hawking is correct, a quantum fluctuation (a singularity) within that initial null environment “appeared” and, guided/driven by the Second law of thermodynamics (Entropy) and chaos (initially in their lowest possible states), acted to evolve space-time and thence drive the energy potential of that quantum fluctuation (singularity) into evolving space-time.
    The Current estimate of the total mass-energy of the observable universe: is = 4×10**69 Joules.
    The question is: given the above, what was the probable minimal amount of energy confined in the initial quantum fluctuation (singularity), now expanded via the second law of thermodynamics (entropy), interacting with increasing chaos to create the present dimension and contents of the universe?
    More importantly: is it feasible that all mass-energy in the universe (including the Higgs and gravity) was/were in fact “created” or caused by entropy?