Corey Powell: Fate of the Universe
What determines our
fate? To the Stoic Greek philosophers, fate is the external product of divine
will, ‘the thread of your destiny’. To transcendentalists such as Henry David
Thoreau, it is an inward matter of self-determination, of ‘what a man thinks of
himself’. To modern cosmologists, fate is something else entirely: a sweeping,
impersonal physical process that can be boiled down into a single, momentous
number known as the Hubble Constant.
The Hubble Constant
can be defined simply as the rate at which the Universe is expanding, a measure
of how quickly the space between galaxies is stretching apart. The slightest
interpretation exposes a web of complexity encased within that seeming
simplicity, however. Extrapolating the expansion process backward implies that
all the galaxies we can observe originated together at some point in the past –
emerging from a Big Bang – and that the Universe has a finite age.
Extrapolating forward presents two starkly opposed futures, either an endless
era of expansion and dissipation or an eventual turnabout that will wipe out
the current order and begin the process anew.
That’s a lot of
emotional and intellectual weight resting on one small number. Both the
retrospective and the prospective interpretations of the Hubble Constant have
stoked ongoing controversy in the 90 years since Edwin Powell Hubble published
the first definitive evidence of an expanding universe in 1929. Recently,
the controversy has taken on yet another guise, as increasingly precise
techniques for measuring the expansion rate have begun to yield distinctly
different predictions. The discrepancy has cosmologists wondering whether they
are missing important elements in their models of how the Universe evolved from
the Big Bang to today....
https://aeon.co/essays/how-they-pinned-a-single-momentous-number-on-the-universe