We’ve known for a long time that the universe is constantly expanding. It was predicted by Georges Lemaître in 1927, and it was empirically proven two years later by Edwin Hubble (this is what the Hubble telescope was called in his honor more than half a century later) by measuring the distance to a dozen or so more. galaxies.
means The fact is that since the Big Bang, matter that is not gravitationally bound to one another (currently, for example, galaxies or galaxy clusters too far apart to interact) has been constantly moving away from each other. Things don’t move much in opposite directions as the spacetime in which they are located expands.
New Calculations of the Expansion of the Universe
We also know that the universe is expanding faster and faster (although we don’t know why), and the rate of this expansion is described by the Hubble constant. Determining it precisely is very difficult, because it is difficult to accurately calculate the distance that separates us from other galaxies. However, this can be done using the so-called standard candles (things for which it is easy to calculate the distance). They are usually Cepheids, that is, very bright variable stars that periodically and noticeably change their brightness (pulsatile).
Now scientists have made it However, recalculationBased on highly detailed observations of the Hubble Space Telescope. Hubble images span nearly 30 years and contain more than 40 different galaxies (36 of which can be seen in the image below) — each containing both Cepheids and supernovae (exploding stars that just expire).
Image Credit: NASA, ESA, Adam G.Ress (STScI, JHU)
By calculating the distance from Earth to these objects, scientists determined that the Hubble constant is 73 . how much per second per megaparsec (this is a distance unit, about 3.26 million light-years). This means that two objects separated by 1 megaparsec are moving at a speed of 73 km per second. Previously, astronomers assumed this value to be 67.5 km (+/- 0.5 km) per second per megaparsec. This is a big difference.
The researchers note that the latest Hubble calculations are accurate. They say the probability of making a mistake is one in a million, which is enough to make the new value true.
However, scientists are still unable to explain why the expansion of the universe continues to increase and is now faster than it was billions of years ago. Perhaps only future research will help find an answer to the question of what “drives” the expansion of the universe.
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