Des chercheurs proposent une nouvelle estimation de la constante de Hubble la plus précise jamais obtenue par les observations. © allexxandarx, Adobe Stock

Hubble takes another step in determining the rate of expansion of our universe

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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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.

for us being increases. There is no doubt. What is the debate is Speed that continues today a movement. Current expansion rate – which translates through that which Physicists Mayor, Hubble’s 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 in the early 1970s were aimed at developing a tool capable of solving Cepheids. Because the civid, changing starshave always served as cosmic signs, a kind of standard scale for Measuring distances in the universe. Exactly since 1912. They can be observed in and inside our Milky Way galaxies Far away, thanks to the Hubble Space Telescope, is about 80 millionlight years.

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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 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) on our primordial world and according to Standard Cosmic ModelTheorists 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 The gravity.

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