Since the discovery of the expansion of the universe, or so, the question has tormented astrophysicists. How fast is this continued expansion today? Because observations and theory do not give the same answer. Today, the Hubble Space Telescope provides additional resolution.
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[EN VIDÉO] Interview: Why is the universe expanding? With the discovery of the expansion of the universe came other questions: How fast is this expansion happening? Is there acceleration? or slowed down? Futura-Sciences interviewed Aurélien Barrau, an astrophysicist specializing in cosmology and author of Des univers multiples.
Our world is expanding. There is no doubt. What is the debate is Speed that continues today a movement. Current expansion rate – which translates through that which Physicists baptized, and Hubble constant. It was a tribute to the Americans Edwin Hubble Who discovered the phenomenon of the expansion of the universe and made the first measurements of it in the twenties of the last century. Today, the tribute has been further strengthened as researchers have revealed something new new results More accurate than ever. Obtained from data collected over 30 years by Hubble Space Telescope.
It must be remembered that scaling was precisely one of the main reasons for the existence of this tool. Efforts since the 1970s have been aimed at developing a tool capable of solving a problem cefid. Because the civid, changing starshave always served as cosmic signs, a kind of standard scale for Measuring distances in the universe. Exactly since 1912. Both can be monitored in our country Milky Way just in galaxies Far away, thanks to the Hubble Space Telescope, is about 80 millionlight years.
When Hubble was launched in the 1990s, the first series of Cepheid observations were made. With the main objective of refining the measurement of distances of galaxies close to our own. In the early 2000s, efforts Astronomy scientists They were rewarded. Thus they were able to deduce value from Hubble constant With an accuracy of 10%. The value of 72 is plus or minus 8 kilometers per second per megaparsec (km / s / Mpc).
What is the correct value?
To improve on this value, the researchers then added new cameras to the space telescope. With the idea of achieving 1% accuracy. Led a special idea to cooperate Supernova, H0, for the dark energy state equation (SH0ES).
Thus, the new findings the researchers published today are based on a sample of cosmic markers that has more than doubled. It also includes an up-to-date analysis of historical data. In all, 42 supernovae – although Hubble witnesses a Supernova explosion Annually, approx… – Also useful for determining distances in the universe. Thus astronomers estimate, given the size of their sample, only one chance in a million, the probability “Who tied the unlucky”. The value of the Hubble constant is about 73 km / s / Mpc. Exactly 73.04 +/- 1.04 km/s/Mpc.
The problem is that from the measurements Planck’s mission (European Space Agency, ESA) at the beginning of our universe and according to the Standard Cosmological Model, theorists predict the value of the Hubble constant which should be 67.5 plus or minus 0.5 km/s/Mpc. So where does this contradiction come from? Astronomers still do not know. But it is possible that they will look for the answer somewhere in the new laws of physical. a A very recent study It tries, for example, to explain the discrepancy using a file ” Globalism Mirror» Only invisible particles that interact with our world via gravity.
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