The measurement is about eight times more precise than Hubble’s expected capability. This can be used to predict that the universe will double in size in 10 billion years. When the Hubble Space Telescope was launched in 1990 the universe’s expansion rate was so uncertain that its age might only be 8 billion years or as great as 20 billion years.Īfter 30 years of meticulous work using the Hubble telescope’s extraordinary observing power, numerous teams of astronomers have narrowed the expansion rate to a precision of just over 1%. The brightest, and therefore farthest detectable milepost markers are Type Ia supernovae. This required building a string of cosmic distance ladders assembled from sources that astronomers have a reasonable confidence in their intrinsic brightness. He suspected his measurements might be evidence of something else more oddball going on in the universe.įor decades after Hubble, astronomers have toiled to nail down the expansion rate that would yield a true age for the universe. Hubble even said that he studied the galaxies simply as “markers of space.” However, he was never fully convinced of the idea of a uniformly expanding universe. This could be interpreted as the uniform expansion of space. Hubble found that the farther a galaxy is, the faster it appears to be moving away from us. And, the galaxies weren’t standing still. The first act of this revelation came when, a century ago, American astronomer Edwin Hubble discovered myriad galaxies outside of our home galaxy, the Milky Way. Furthermore, we wouldn’t have any idea about its age either – or in fact, if the universe was eternal. Without any observational evidence for space expanding, contracting, or standing still, we wouldn’t have a clue as to whether the universe was coming or going. Science history will record that the search for the expansion rate of the universe was the great Holy Grail of 20th-century cosmology. Credit: NASA’s Goddard Space Flight Center Three Decades of Space Telescope Observations Converge on a Precise Value for the Hubble Constant More recently, the expansion has begun to speed up again as the repulsive effects of dark energy have come to dominate the expansion of the universe.
(Size is depicted by the vertical extent of the grid in this graphic.) For the next several billion years, the expansion of the universe gradually slowed down as the matter in the universe pulled on itself via gravity. The far left depicts the earliest moment we can now probe, when a period of “inflation” produced a burst of exponential growth in the universe.
A representation of the evolution of the universe over 13.77 billion years.
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