The expansion rate of the universe is now beginning to be measured in different ways with high precision, and it seems that the actual differences may point to new physics beyond our current knowledge of the universe," says the lead researcher
Using galaxies as giant gravitational lenses, a team of astronomers using the Hubble Space Telescope were able to make independent measurements of the expansion rate of the universe. The expansion rate of the local universe is consistent with previous findings. However, there is disagreement regarding the measurement of the expansion of the early universe. This suggests a fundamental problem at the core of our understanding of the universe.
Hubble's constant - the rate at which the universe expands - is one of the fundamental parameters that describe our universe. A group of astronomers from the H0LiCOW collaboration, led by Shari Soyo, which includes researchers from the Max Planck Institute for Astrophysics in Germany, and the ASIAA Technical University in Taiwan used the Hubble Space Telescope and ground-based telescopes to study five galaxies and arrive at an independent measurement of the Hubble constant.
The new measurement is completely independent but it confirms the Hubble constant in the nearby universe, as measured by cupid particles and supernovae as reference points.
However, the value measured by Soyo and her team, as well as the Cepheid variables, is different from the measurement of the European Space Agency's Planck satellite, but there is an important difference: Planck measured the Hubble constant for the early universe by observing the cosmic background radiation.
While the value for Hubble's constant determined by Planck is consistent with our current understanding of the universe, the values obtained by different groups of astronomers for the local universe are at odds with our accepted theoretical model of the universe. "The expansion rate of the universe is now beginning to be measured in different ways with high precision, and it seems that the actual differences may point to new physics beyond our current knowledge of the universe," Suyo says.
The targets of the research were massive galaxies located between the Earth and very distant quasars - luminous galactic cores from the early universe. The light from the distant quasars was bent around the large masses of the galaxies as a result of a process called gravitational priming that operated with great force. This results in the creation of a large number of images of the quasar in the background, some of which are smeared as rainbows.
Since galaxies do not create perfect spherical distortions in the fabric of space and the galaxies and quasars are not perfectly aligned in our line of sight, differences arise between the various images of the quasar. Because the brightness of quasars varies over time, astronomers can see that the different images flash at different times, the delays caused by the path the light takes. These delays are directly related to the value of Hubble's constant. "Our method is the simplest and most direct way to measure Hubble's constant as it is using only geometry and general relativity without additional assumptions," explains Soyo's research partner, Frederic Corbin from EPFL in Switzerland.
Using precise measurements of the time delays between a large number of quasar images, plus computer models, the team was able to determine the Hubble constant with an impressively high accuracy: 3.8%. "A precise measurement of the Hubble constant is one of the most coveted prizes in cosmological research today," emphasizes team member Vivienne Bonvin from the EPFL in Switzerland. Vesuyo adds: "Hubble's constant is critical to modern astronomy because it can be used to confirm or disprove our picture of the universe consisting of dark energy, dark matter and normal matter – or whether we are missing something fundamental."
Is dark energy responsible for accelerating the expansion of the universe?
Nobel Prize for discovering the acceleration of the expansion of the universe
13 תגובות
Chen Chen Digi!, happy to come up with reflections on various scientific topics. Scientific progress is always made while imposing sufficiency. You can also enter my blog:
http://yekumpashut.freevar.com/
good day everybody
Yehuda
Thanks Yehuda!
Always enjoy reading your comments
Opens my mind and inspires
mouthhole,
Thanks…?
Shmulik,
I would say yes. Penrose is one of the most important physicists in the development and promotion of relativity as it is known and understood today, and the ideas he conceived and applied proved to be useful and important in other fields as well. There is even one of his contributions to the field that you may also be familiar with - the Penrose diagram. If you google it, you'll see what diagrams I'm talking about. It is likely (though not certain) that you have encountered such drawings before, whether depicting black holes, our universe, or a host of gravitational systems. Although a method that allows you to draw something may not sound like the most important thing in physics, it involves a mathematical approach that was innovative at the time and today is the standard for more or less all theories of gravity.
Hi Albantezo,
Thank you very much for the detailed answer. I wonder why he doesn't publish his review in the form of an article.
I should have written that I am in the middle of viewing and if there is another reference, I will update.
By the way, I once heard a sentence that roughly said that thanks to Einstein we have the theory of general relativity but thanks to Penrose, we also understand it. You also briefly referred to his contribution. Was his contribution to understanding the subject so decisive?
What a king you are Albenzo 🙂
Shmulik,
I'm good, thanks. How are you?
Regarding Penrose, I must say that I didn't delve too much into his review - I saw the clip you sent (at least the relevant fifteen minutes, if he comes back to it later tell me, because I stopped watching when they changed the subject). Beyond that, I read a bit on the Internet, but I did not read the book in which, to my understanding, the review is found in its most complete form.
I think that the answer (or at least the thoughts that came to me in an associative way upon hearing the review, I'm not sure if this is the answer because I didn't internalize the question to the end) can be divided into two parts. One concerns the question as it is formulated in the video, which is "What happens if we induce vibrational modes in compact dimensions?" And the second to the question of whether the number of physical degrees of freedom in such a multidimensional system can correctly describe our world (which is more appropriate to the wording of the criticism I found in various sources on the Internet during a short Google search).
Regarding the first question, the answer is that I don't really think there is a problem with it. First of all, it is true that although we cannot study the compact dimensions because they are too small (and therefore the energy needed to disturb them is too great), it is possible that naturally in nature there are such excitations. Although it is not as simple as he presents it (because high-energy processes such as those that occur on cosmological scales tend to emit their energy over large distances, in other words the energy density is not necessarily great), but it is possible. This would only be a real problem if the disruption of the compact modes would result in the collapse of the universe, as he implies. But this is not true - there have been known mathematical models for many years of such universes within the framework of string theory which are stable (or semi-stable, with a life time that is much longer than the time our universe exists).
Regarding the second question, which is a little more technical and may be a little more difficult to understand for people who are not familiar with the field - the number of degrees of freedom in string theory is misleading. On the face of it there seem to be ten dimensions and therefore there are many more degrees of freedom for one field or another than what we would expect from a four-dimensional system, but string theory is not simply field theory. This is where the holographic principle comes into play, which says that the degrees of freedom in these ten dimensions are actually the same degrees of freedom as in a smaller, gravity-free system. For the most famous example (which also has a real mathematical proof and is not just a hypothesis), it is possible to explicitly build a system with ten dimensions, five of which are compact and in fact its degrees of freedom are equivalent to a 4-dimensional system without gravity. It won't describe our universe (for reasons I won't go into now, this particular example just doesn't fit because it doesn't have the right cosmological structure), but it is an example that illustrates that a naive count of degrees of freedom (three times infinity to the power of three, as Penrose says) is Just wrong.
Penrose is a great physicist and an excellent mathematician who is responsible for a great many advances in the study of gravity in the twentieth century, but in my opinion this is a classic case of stubbornness. There will always come some "kid" with a new idea that will be foreign to the previous generation of scientists and some will insist on rejecting it for reasons of principle, because it is not what they are familiar with. Again, without disparaging this great scientist at all (and without forgetting that I haven't really delved into his criticism yet), I get the impression that most of his criticism is related to the fact that he didn't really study string theory in depth, but tries to reject it for reasons of principle.
Albantezo, how are you?
I recently watched a very interesting lecture by Roger Penrose. At about the XNUMXth minute, he starts talking about the problematic nature of string theory, mainly in terms of its dimensions. He talks about a problem arising from "functional freedom" (degrees of freedom of a function?) and energy levels that we were supposed to measure...
He also sends blame to the community by raising the issue but not receiving any further than initial consideration.
I roughly understood his claim and I would be happy if you would clarify the issue a bit. Is there an answer in the community?
I also found a reference in a certain forum, but the answer is too much for me.
This is YouTube:
https://youtu.be/3OsE8NETbNQ
This is the link from the forum
http://www.physicsoverflow.org/38040/penroses-functional-freedom-objection-dimensional-theories
Thanks!
to Diggy and others
I find it hard to believe that a study done on five galaxies would be a good statistical model for testing the size of the Hubble constant. Even so, it is difficult to measure because we are inside the universe we are measuring. Therefore, I believe more to state that we were measured by the Planck satellite that tested a larger sample..
First of all we are talking about periods of billions of years ago and apparently even more than ten billion years. I have no possibility today to determine important data for the purpose of measurement, for example, was the speed of light the same as it is today? After all, a change of a few percentages in these factors would have turned the question upside down and the article would have read:
New research reveals that the early universe expanded much more slowly than today
Another important thing is the problematic nature of the gravitation formula. What do things mean? Well, Newton's gravitation formula is a formula that was obtained inductively from measurements he had from Kepler, Tycho Brahe and others. All these data were obtained only from data that Newton had up to a distance of about ten astronomical units and he "guessed" from them his well-known formula. Later, the planets Uranus, Neptune and the dwarf planet Pluto were also discovered (a distance of about forty astronomical units, which is less than a thousand light years!) and they also behaved according to Newton's formula. But since then no confirmation of Newton's celebrated formula has been received. Any attempt to determine it as correct for distances greater than a thousand light years will encounter a huge lack of gravity which we supplement with the "invention of the twentieth century" - the dark matter. So we must ask ourselves whether Newton's formula is also compatible with the great distances of the galaxies of ancient times, of the enormous masses in question. Indeed, I may only agree with the ending of the article "that measurement is important in determining dark matter and energy" because this is what will happen if you decide to hold on to the altar horns of the Newtonian formula.
I, your faithful servant, think that the Newtonian gravitation formula on which this article is based, is not valid in this case of extreme/distant/enormous distances, masses and times, and another phenomenon drives the universe.
Please, please respond gently. Saturday today, Saturday today, Saturday
Sabdarmish Yehuda
http://yekumpashut.freevar.com
Digi, did you call me? If so I won't disappoint you and will read and respond in about an hour.
Yehuda
Where did Yehuda disappear?
Yehuda will return to us
The universe is not the result of expansion but of contraction
Applying a tiny 360px × 360px image is the best you could come up with.
And the most annoying thing is to click on it and find out that it is smaller than what is shown on the website.
I'm sorry, but I expected a little more from a scientific site.