Research, Technology

New value of the Hubble constant: why is the Universe expanding with acceleration?

Our universe is expanding at an accelerating raterather strange indeed: according to early cosmological models, the expansion of the universe should have slowed down over time. Astronomers came to this conclusion from the assumption that the bulk of the mass of the universe is matter - both visible and invisible (hello, dark matter). This theory, however, was not confirmed and, as we know today, the universe is expanding at an ever-increasing rate. Moreover, it also obeys the unknown laws of physics. In academic circles, this problem is called the Hubble constant and represents a serious crisis in cosmology. But why?

The expansion of the universe is a strange thing. Early cosmological models suggested that it was slowing down. But is it really so?

Hubble constant is the number that astronomers use to measure the expansion of the universe. The constant got its name in honor of the astronomer Edwin Hubble, who first measured it in 1929.

Expansion of the universe

An event that occurred about 14 billion years agomade our existence possible. The Big Bang started everything we know. But to understand how the Universe works and according to what laws it works is not easy. So, existing physical theories cannot explain why the universe is expanding faster and faster. But how did we even know about it?

It all started about a hundred years ago whenAmerican astronomer Edwin Hubble discovered other galaxies outside the Milky Way and concluded that they are constantly moving away from us. This discovery has become real breakthrough in our understanding of the cosmos.

It is estimated that the accelerating expansion of the universe began approximately 5 billion years ago.

Hubble itself, however, the result was notglad. The fact is that scientists still cannot come to a consensus on this matter. And although in 1998, by studying distant supernovae, astronomers proved the expansion of the universe, it was not possible to accurately determine its speed.

More on the topic: The beginning of the end of the universe: the secrets of dark energy

To begin with, measurements of the expansion rate of the universe typically focus on two distance markers. One of them are cepheid - variable stars that brighten and dimat a constant speed. Their existence became known to the world in 1912, when astronomer Henrietta Swan Leavitt noted their importance while reviewing images taken with space telescopes.

Cepheids are good for determining distances withinMilky Way and nearby galaxies. In addition to them, astronomers also rely on the brightness of supernovae - a phenomenon in which a star sharply increases its brightness by 4-8 orders of magnitude.

Hubble Space Telescope

Today, many observatories observedifferent parts of the night sky, but the data obtained are very different from each other. The same goes for the Hubble Space Telescope, which has served humanity faithfully for over 30 years. And although the expected lifetime of the telescope has long expired, Hubble still reveals the Universe to us.

The recently discovered accelerated nature of the expansion of the Universe causes a lot of controversy and leads to the emergence of a large number of hypotheses.

In a study published in the scientificin the journal Physical Review Letters (as part of the SHOES project), scientists analyzed 42 supernovae, one of which exploded about once a year. The astronomers then calculated a new value for the Hubble constant, including better estimates of the age of the universe and its future.

The researchers note that a new dimension ineight times more accurate than the previous ones and is 73±1 km/s per 1 Megaparsec. The new figures are based on a dataset that includes more than 1,000 Hubble Space Telescope orbits.

The obtained calculations also indicate that the expansion rate of the Universe is non-uniform: distant galaxies are moving away fasterthan those closer to us. The difference between new and previously available data reaches 9%, but the opinions of scientists are again divided.

Cosmology is the scientific study of the large-scale properties of the universe as a whole. It seeks to use the scientific method to understand the origin, evolution, and ultimate fate of the entire universe.

Over the past 30 years, the world has learned a lot about the universe. And we owe this knowledge to the Hubble Space Telescope.

The researchers also discovered a previously unnoticed mathematical property of cosmological models: The mysterious dark energy is responsible for the expansion of the universe. It is believed that it makes up most of the energy in the universe, but what exactly it is is still unknown.

The fate of the universe

Paying attention to valuable hints aboutthe ultimate fate of the universe, then it will most likely continue to expand. As a result of this process, matter will become less dense and decay due to the so-called heat death.

Heat Death of the Universe - the probability that sooner or later any part of the system will return to its original state.

Can our universe exist forever?

But what if different exponents of the Hubble constanttestify to the existence of a certain mirror universe? In scientific theory, mirror worlds have been described more than once, which can affect changes in gravity. Surprisingly, this assumption does not contradict the existing ideas about the speed of photons. It turns out that the mirror world invisible to observers can have a symmetrical effect on everything that happens around.

Since cosmology covers the entire universe frombirth to death, concepts like dark matter, dark energy and the multiverse are being seriously considered by respected scientists. Read more about how the world can be arranged, we told earlier, do not miss it.

Observable galaxies are moving away from us faster and faster

Based on the results of a new study, soonphysicists will be able to answer a whole range of questions, and in the next 20 years the James Webb Space Telescope will make additional measurements of the Hubble constant. Recall that, located in space and equipped with the latest instruments, Webb will continue the work of Hubble, carefully and in detail considering space landmarks.

In the meantime, the secrets of the universe have not been revealed, the constantHubble is still the subject of heated debate in the astronomical community. What laws do you think govern the Universe and why? The answer, as always, will be waiting here, as well as in the comments to this article.