The universe was born about 14 billion years agoas a result of the Big Bang. Since then, it has been expanding continuously. But we learned about this a little less than a hundred years ago. In 1920, the American astronomer Edwin Hubble invented the largest telescope in the world at that time, and his colleague Vesto Slifer noticed the red glow of the nebula - what we call galaxies today - and determined that the nebulae seem red to us because are moving away from our planet. This effect is called redshift - the radiation observed for all sources far from the Earth (quasars, galaxies), which indicates that all sources are moving away from each other. In other words, redshift means that the universe is expanding. Recently, scientists wanted to calculate the exact rate of its expansion. It turned out that in our understanding of the Universe there may be fundamental inaccuracies.
What is the Hubble constant?
Edwin Hubble Observes the NebulaAndromeda was able to classify it as a star system. The discovery of the astronomer expanded our understanding of the Universe - now we know that it is filled with galaxies. Thus, Edwin Hubble discovered the cosmological law that characterizes the expansion of the universe. To calculate the speed with which the Universe expands, it is necessary to use the proportionality coefficient - the Hubble constant.
Using the Hubble constant, you can determinethe average velocity of galaxies. The value of the proportionality coefficient, derived by the scientist, is approximately 500 km / s per 1 Mpc. Recall that space distances are measured in parsec: 1 parsec equals 3.0857 • 1019 kilometers. And one megaparsec is the distance of a million parsec.
However, from the moment Hubble pulled outconstant, astronomers who observe the expansion of the universe, each time come to different values of the Hubble constant. And these values are not consistent with each other. Such a discrepancy raises doubts about our ability to determine the exact age of the universe and even question our understanding of its fundamental laws.
So how fast is the universe expanding?
A team of researchers led by an astronomerUniversity of Chicago Wendy Friedman measured the brightness of red giants in distant galaxies. The study revealed that the distance from Earth to the red giants turned out to be easier to calculate than the distance to other stars. Thus, according to the calculations of astronomers, the Universe is expanding at a speed of 69.8 km / s per 1 Mpc. Note that the results of the study will soon be published in the journal Astrophysical Journal.
This is interesting: Can gravitational waves reveal how fast our Universe is expanding?
As you may have noticed, the results obtaineddifferent from those calculated by Hubble. According to the work of Friedman and her team, the expansion rate of the universe is slower than the speed that another team of scientists calculated in a recent study - in it, experts focused on a different type of star. However, the results obtained by Friedman exceed the rate of expansion of the Universe, which was calculated in another study, in which astronomers measured the remnant remnant after the Big Bang, also called microwave background radiation.
Thus, the Hubble constant is itselfbig problem of modern cosmology. Experts do not exclude that having determined the speed of expansion of the Universe, we can come closer to unraveling the mysteries of dark matter and dark energy.
By the way, on our channel in Yandex.Zen you can find out about the latest research in the field of cosmology.
Do we know the exact rate of expansion of the universe?
In the middle of the next decade, specialistsNASA hopes to launch the Wide Field Infrared Survey Telescope (WFIRST), a wide-band infrared telescope. Scientists believe that with it, astronomers will be able to more accurately measure the distance between space objects. And this, in turn, can lead us to agree on the values of the Hubble constant.
And what do you think, what do the different values of the Hubble constant indicate? Share your opinion in the comments and with the participants of our Telegram chat.