Ask Ethan: How sure are we that the Universe is 13.8 billion years old? (Synopsis)

“Normal science, the activity in which most scientists inevitably spend almost all their time, is predicated on the assumption that the scientific community knows what the world is like.” -Thomas S. Kuhn

For all of human history, the biggest questions have fascinated us. Where did the Universe come from? How old is it? And what is its ultimate fate? Once relegated to the realm of theologians, poets, and philosophers, science has brought us closer than ever to the answers. But scientific revolutions have occurred before, in many cases significantly changing the answers to these and other inquiries. How certain are we that this won’t happen again?

The Sun, the Earth, and the history of life on our world all have a consistent age today, but back in the late 1800s, the evidence for the age of the Earth suggested it was significantly older than the Sun. Image credit: NASA, ESA, and ISS Expedition 37.

When it comes to the question of the age of the Universe, presently estimated at 13.8 billion years, there are many uncertainties that could come into play. Dark energy could evolve over time, fundamental constants might not be constant, or today’s fundamental particles might be broken up into smaller components. Additionally, we could have flaws in the expansion rate or composition of our Universe, or even alter General Relativity.

The four possible fates of our Universe into the future; the last one appears to be the Universe we live in, dominated by dark energy. What’s in the Universe, along with the laws of physics, determines not only how the Universe evolves, but how old it is. Image credit: E. Siegel / Beyond The Galaxy.

But it really looks like 13.8 billion years is safe, to within perhaps 2% at most. How can we be so confident? Find out on this week’s Ask Ethan!

6 thoughts on “Ask Ethan: How sure are we that the Universe is 13.8 billion years old? (Synopsis)

  1. All I get when I post at Forbes is “please reload and try again.” So here is what I posted:
    Most cosmologists refuse to consider the question, “What, if anything existed over 14 billion years ago?” If nothing, how did it all magically manifest out of nothing.
    Consider the eternally, perpetually oscillating model, even though we can not presently measure the time span of such a two phase, “bang/ crunch” model… given that it’s still expanding at an accelerating rate. No more magic of everything pulled out of a cosmic “magic hat!”

  2. @Another Commenter #1: It’s not that the Hubble “constant” has that large an uncertainty. Rather, it’s that there are two entirely different measurements which come out that far apart, but each with much smaller uncertainties!

    When we use the “cosmic distance ladder” (look it up) to relate redshift values to distances of galaxies, which is the method Hubble himself used, the various observational groups have converged on a value around 72+/-3 km/s/Mpc. Basically, this value is the _current_ Hubble parameter, measured using relatively nearby objects (z < 2 or 3).

    On the other hand, you can use a combination of CMB and "baryon acoustic oscillation" (two-point correlation distances between galaxies) to extract the Hubble parameter. Those observations converge on a value of 67 +/- 0.5 (ish) km/s/Mpc. This value uses observations from much, much higher redshift (out to z ~ 6 for BAO, z ~ 1189 for CMB), but it is still supposed to reflect the expansion rate here and now (because that's what affects our observations).

    Notice that both values are reported to be very precise — that is, the statistical and systematic uncertainties evaluated for each method independently are quite well controlled.

    The problem, as you can see, is that the two different values are not even close to mutually consistent! We currently don't know why. That's why it's an active area of research, and not a final, fixed value (like 'c').

  3. “13-8-billion-years-old is spatially non-inclusive & chronologically inconsistent”.since 5 billioni or so years was required to form this comparatively miniscule solar system that is far less than the 2-400 billions of Ma billionthCheck capstonepublishing@surewest.net

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    13-8-billion-years-old is spatially non-inclusive & chronologically inconsistent.
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    Air Pollution results too from degradation of protective elements there; allowing deeper penetration of destabilizing lethal space rays.
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    10/19/2017
    With widely announced reports of casualties from world pollution being so exceedingly great; the worth of clean air, water and contaminant free soils and foods becomes further emphasized and the need underscored. This also infers that ground water, being tainted by chemically laden ashes from homes and towns that have burned to the ground; homes Containing plastics, household chemicals, electronics casings. industrial solvents etc. that yet need be better prevented from contaminating; and doing so by wise planning and construction and forestry management. Further actual value can be derived from societal pursuits that do not increase or require daily polluting commuting, breathing lingering wildfire smoke, and the equally dangerous fumes from detonated weaponry being used worldwide by peoples not realizing the after effects of lingering barbarism and refusal to rather nurture mutual regard also for the planet’s life sustaining land foliage -plants, trees-and other wildlife, long preceding human presence on tthe planet.

    Further value can be derived from not only abandoning the long adversely ramifying death dealing sado-masochistic world ‘cults of mayhem, injury,decimation and death’ but rather seeking and actually both pursuing and accepting whatever actually leads toward greater global safety and stabiity; and especially when such more optimal outcomes can and do present evidences of sure achievement and attainment, however unprecedented.

    Among such novel occurrences are those widely seen successful demonstrations during the past three decades; of difficult to access wildfires being more quickly suppressed without chemicals and costly air flights, in over two countries and three states. The modes the advanced collaborative modes introduced, saved benefitting states and countries billions in firefighting, restoration & medical expenditures, yet were largely disparaged and likely deemed coincidental. This too underscores how humankind -even when shown better provenances to pursue, are prone to disregard and devalue the implications;, preferring the more risky costly familiar pursuits.

    10/19/2017
    With widely announced reports of casualties from world pollution being so exceedingly great; the worth of clean air, water and contaminant free soils and foods becomes further emphasized and the need underscored. This also infers that ground water, being tainted by chemically laden ashes from homes and towns that have burned to the ground; homes Containing plastics, household chemicals, electronics casings. industrial solvents etc. that yet need be better prevented from contaminating; and doing so by wise planning and construction and forestry management. Further actual value can be derived from societal pursuits that do not increase or require daily polluting commuting, breathing lingering wildfire smoke, and the equally dangerous fumes from detonated weaponry being used worldwide by peoples not realizing the after effects of lingering barbarism and refusal to rather nurture mutual regard also for the planet’s life sustaining land foliage -plants, trees-and other wildlife, long preceding human presence onthe planet.

    Further value can be derived from not only abandoning the long adversely ramifying death dealing sado-masochiswtic world ‘cults of injury, decimation and death’ but rather seeking and actually both pursuing and accepting whatever actually leads toward greater global safety and stabiity; and especially when such more optimal outco0mesw can present evidences of sure achievement and attainment, however unprecedented.

  4. References to this matter was made on cra8gslist months ago, and at wonderfulcounsels.net (an A.T&T. blog, but Bitcoins were being sought for enlisting staff Artists and filmmakers for the more graphic film and video portrayal and book publishing. Many sense the 13. billion year dating lags behind more recent astronomical discoveries, but need more factual elucidation.

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