Isaac Newton was arguably the most brilliant scientist in history. He was certainly unrivaled in his lifetime, during which he invented the reflecting telescope, developed his famous universal laws of gravitation (daring to unite the heavens and the Earth as governed by the same processes) and pioneered the use of mathematical equations in the scientific enterprise, constructing the realm of calculus in the process. He also used the power of mathematics, and the Bible, to calculate that the Earth was created sometime around 4,000 BC. Well, even the best can trip up.
This figure also assumed that the world had existed more or less as it is since that beginning, and that the great variations in landscape we see had been caused by catastrophic events such as floods and powerful earthquakes. James Hutton proposed in 1795 that instead our great canyons and mountain ranges had been formed by the same processes of erosion and weathering we observe today, necessarily taking place over much vaster lengths of time. Catastrophism thus gave way to gradualism, an idea further cemented by Charles Lyell, one of the pillars of geology.
So the Earth was much older than we thought, but how much older? in 1897, Lord Kelvin assumed that our world began in a molten state and calculated it would need 20-40 million years to cool to its present temperature. A helluva lot older than 6,000 years, but still not close by a longshot. Kelvin didn’t know about radioactive decay, which contributes enormous amounts of heat that “fooled” him into thinking the Earth was younger than it is. Thankfully we now understand the process well, so much so that we’ve used radiometric dating to finally get a good handle on the planet’s age, a whopping 4.5 billion years, a figure we still didn’t arrive at until the 1950′s.
Okay, okay, so the Earth has changed drastically over time, but the universe – now THAT’s eternal and unchanging! Right? I mean, that’s what Einstein thought. He wanted the universe to remain static so badly that when his own theory of relativity showed that it must be expanding, he threw in a MacGuffin called the “cosmological constant” to fudge the numbers! And if there’s one thing we’ve learned, it’s that the most brilliant scientist of his time can’t be wrong! Wait…
Edwin Hubble refined the first numerical estimates for the universe’s expansion made by George Lemaître, and by combining that with the known distances to certain astronomical features, he arrived in 1929 at a cosmic lifespan of 2 billion years, a figure he himself called “suspiciously short,” as many stars seemed older than that and the geologists had already brought the age of the Earth to at least 3 billion years. Better distance measurements to Cepheid variable stars and quasars in subsequent decades continued to raise the age of the universe, from 6, to 10, to 12 billion years.
In 2008, the Wilkinson Microwave Anisotropy Probe (WMAP) revealed the most precise appraisal yet, further aging the universe to 13.7 billion years. And now the European Space Agency’s Planck spacecraft has used the same primordial quantum fluctuations to kick it a tiny bit more, for a final figure of 13.82 billion years.
Thanks in part to the Planck spacecraft, the universe if billions of years older than it was a century ago
WHAT DOES THIS MEAN?
The continuing changes to a single piece of information may seem damning at first blush, but it’s really a monument to how beautifully self-correcting science is. No ideas are sacred, no matter who came up with them, and all positions are open to revision when new or better evidence is presented. If the argument of an iconoclast is sound, it cannot be ignored. Not all institutions are so democratic or flexible.
But then again, the wiggly, fiddly findings do also reinforce that science can only offer approximations of the way things are. No one can provide true certainty, but through the advancement of ideas and technology, our approximations of reality become ever better and the picture of our vast, ancient universe becomes clearer.