“Nobody grows old merely by living a number of years. We grow old by deserting our ideals. Years may wrinkle the skin, but to give up enthusiasm wrinkles the soul.” -Samuel Ullman

When it comes to the Universe, there are some dead giveaways as to what its age is. Its elemental composition changes, the types of stars that are present evolve, the large-scale structure visible to us morphs, grows and ceases, and the temperature of the cosmic microwave background drops, among many other signs.

Image credit: Suzuki et al. (The Supernova Cosmology Project), accepted for publication, Ap.J., 2011., via http://supernova.lbl.gov/Union/.

Image credit: Suzuki et al. (The Supernova Cosmology Project), accepted for publication, Ap.J., 2011., via http://supernova.lbl.gov/Union/.

Yet when we put them all together, there are only two methods available to measure the age of the Universe: the measurement of its expansion history and the measurement of the age of the oldest stars. The first is by far the more accurate, at 13.81 billion years (plus or minus just 120 million), while the second validates that picture, with a maximum age of 13-to-14 billion years.

Image credit: Joel D. Hartman, Princeton University, via http://www.astro.princeton.edu/~jhartman/M3_movies.html.

Image credit: Joel D. Hartman, Princeton University, via http://www.astro.princeton.edu/~jhartman/M3_movies.html.

Go learn the full story, plus how we arrive at that number, over on Forbes today!

Comments

  1. #1 See Noevo
    April 29, 2016

    From Ethan’s Forbes article:

    “Under the laws of General Relativity, if you have a Universe like ours, which is:
    1) of uniform density on the largest scales,
    2) which has the same laws and general properties at all locations,
    3) which is the same in all directions, and
    4) in which the Big Bang occurred at all locations everywhere at once,
    then there is a unique connection between how old the Universe is and how it’s expanded throughout its history.”

    Well, if the carnival performer insists on continuing to bark this stuff, then I feel obligated to bark back:

    Point 1) is objectively false.
    Exhibit A: The billion light year-wide stellar formation Boss Great Wall.
    Exhibit Z: The most un-homogeneous little “lump” known as See Noevo, who’s thinking about this.

    Point 3) is objectively false, for the same reasons as 1) is.

    Also, regarding this “uniform density”, which I’ll take the liberty to call “homogeneity” (i.e. one of the assumptions of Big Bang Theory),
    I’m assuming that the 7th image in your Forbes article – the orange and blue ellipse – is supposed to represent some aspect of the homogeneity of the universe.
    But can you imagine looking into a glass of supposedly homogenized milk and seeing the un-homogeneous clumpiness of figure 7?
    What would you do?
    I know what I’d do: I’d throw it out.
    ..…………..
    Now, point 4) is a relatively new lame duck.

    I think most people think of the Big Bang as emanating from a teeny tiny point.
    So, they would readily agree that, even though the reason for the BB is inexplicable, the BB occurred at all locations everywhere at once. They’d agree simply because it’s easy to cover all locations when all locations are confined to one teeny tiny point.

    But now I think you’re saying that what actually emanated from the teeny tiny point was a pre-Big Bang Inflation, and then, when the universe was much, much bigger than a teeny tiny point, it went POP!
    But this pop (i.e. Big Hot Bang?) occurred at all locations everywhere at once…for some reason.

    I think most people might not readily agree to that.
    Those outside the carnival, I mean.
    …………………
    Ethan: “This means we’re confident in the age of the Universe to 99.1% accuracy, which is an amazing feat!”

    I would think that you’d think this was amazingly disturbing. Because this would mean you might be off by 0.90%!
    That’s over four times higher than, well,
    see, in an earlier blog, you said that
    ““false alarm probability” of 0.22% is actually quite high, for physics standards!”
    …………….
    Ethan, do you have any pictures of you in clown makeup?

  2. #2 dean
    United States
    April 29, 2016

    sn, the real question is whether you have any support for your objections that hasn’t already been shown to be nothing more than your lack of understanding and misrepresentations?

  3. #3 Denier
    United States
    April 29, 2016

    Just double checking here, but does SN believe the universe is ~10,000 years old?

  4. #4 Narad
    April 29, 2016

    Point 1) is objectively false.
    Exhibit A: The billion light year-wide stellar formation Boss Great Wall.

    You don’t understand either the word “density” or “scales.”

    HTH. HAND. FOADIAF.

  5. #5 Naked Bunny with a Whip
    April 29, 2016

    Good grief. I can safely say the water in my glass is of a uniform average density, even though most of the mass is concentrated into tiny nucleons surrounded by relatively vast stretches of space, and there are doubtless small temperature variations.

  6. #6 PJ
    Perth, west Oz
    April 29, 2016

    Good one, bunny …..

  7. #7 Narad
    April 29, 2016

    S.N. resents things that are beyond his grasp. The simplest answer to his making an ass of himself over homegeneity is to observe that it follows directly* from isotropy unless the observer is in fact the center of the universe.**

    There is no detectable CMB anisotropy above the scale of the distance to the surface of last scattering. End of story.

    * Nonperturbative FLRW only? Any help appreciated.
    ** Or can specify its location.

  8. #8 Narad
    April 29, 2016

    ^ For spacelike slices.

  9. #9 Narad
    April 30, 2016

    I’m assuming that the 7th image in your Forbes article – the orange and blue ellipse – is supposed to represent some aspect of the homogeneity of the universe.
    But can you imagine looking into a glass of supposedly homogenized milk and seeing the un-homogeneous clumpiness of figure 7?

    Oh, dear G-d, it’s referring to the 2013 Planck CMB map. Go look into your glass of milk through a 20,000× lens.*

    * I think that’s the contrast enhancement on the final image.

  10. #10 Narad
    April 30, 2016

    ^ Heh, silly me, the raw-milk branch of Sally Fallon’s crank collective has done it at 4200×.

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