Pressure on the Hubble pressure

A recent study of the Hubble strain won the 2011 Nobel Prize in Physics Adam Rice et al., has added fuel to the fuse of a controversy brewing by the minute at the nerve center of astronomy. Rice, a Nobel laureate, concludes the work with the phrase: “Once measurement errors are ruled out, there is a real and exciting possibility that we have misunderstood the universe.” The phrase is a cool shot.

Riess's paper has been asserted in several media outlets as maintaining and strengthening the Hubble tension. But the opinion of many astronomers is that their results are so strong that the tension with them disappears and creates a deep crisis. cosmological model, helping to explain the universe. The universe we tell ourselves.

Data on the expansion of the universe obtained through the article are used The James Webb Space TelescopeThis confirms the results obtained earlier Hubble Space Telescope (HST) on the value of the Hubble constant. I mean for both of them Giants Everything is as expected. But there are measurements that cast doubt even on giants.

expansion of the universe

Edwin Powell Hubble And his collaborators, just over 100 years ago, were the first to show that the universe is more or less the same in all directions and as far as telescopes can observe. But they also discovered that the entire galaxy is expanding.

This is one of the greatest scientific discoveries of all time: the modern equivalent The Copernican Revolution. From that moment on, astronomers began measuring how much it was expanding and at what rate it was doing so, until establishing the current rate of cosmic expansion. Knowing this data, it is possible to tell the origin and the hidden history of the universe.

Search for two numbers

The universe is big, old and disordered. For most of the last century, physicists, astronomers, and cosmologists used the general theory. Einstein's relativity And they made cosmological observations to find out how big, how old, and how irregular it is, as well as clarifying whether the cosmic expansion will continue forever or reverse and crush our distant descendants.

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In 1970, the late astronomer Alan Sandage wrote a Most Cited Article We can point to two numbers that bring us closer to the answers to these questions, measure them, and see how they change over cosmic time. Those numbers are the Hubble constant, H₀, and the deceleration parameter, q₀.

The first of these two numbers indicates how fast the universe is expanding. Its current value is the Hubble constant, denoted H₀ (by Hubble, who collected the first data to derive its value). Astronomers measure it in slightly different units (kilometers per second megaparsecabbreviated as km/s/Mpc).

Discrepancy in measurements

But today we have two ways of determining the current rate of cosmic expansion. The direct method is based on measuring the inertial velocities and distances at which large numbers of galaxies are located. Hubble-Lemaître Lay The Hubble constant indicates that its stock no. If the value H₀ Obtained this way by Hubble would have been correct, the age of the universe would be only about 2 billion years: that would be younger than the Earth and many stars!

From what has been said so far, general relativity is firmly established, while the interpretation of observations, due to the work Sandage began, significantly increased the reading distance and, consequently, the duration. The universe is surrounded.

Three Steps to Measuring the Hubble Constant: NASA, ESA, A. Feild (STScI), and A. Riess (STScI/JHU). Image of CMB, Planck satellite and its analysis: ESA and Planck collaboration. A picture of cosmic history since the Big Bang: NASA/WMAP Science Team – Wikimedia Commons Modified by Serkash. HST and JWST images: NASA/ESA/Hubble/CSA.

An obvious conflict

For those who remember the “old days”, when H₀ 50 or 100 and the age of the universe is 20 or 10 billion years, we were relieved to see how in 2002 H₀ The results settled at 72 km/s/MPC The main HST project is led by Wendy Friedman. As a result, the age of the universe is about 13.8 billion years. He True heroism obtained by Rice and his colleagues using this method H₀= 73,0 ± 1,0 km/s/mpc.

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But, as we announced, there is a second way to get value H₀. This can be inferred very precisely from a detailed analysis of maps of the cosmic microwave background (CMB), the radiation left over from the Big Bang, which began traveling about 13.5 billion years ago.

Data obtained by scientific teams from satellites Blank Y WMAP They have been analyzed in conjunction with other cosmological data to obtain values ​​of different parameters that describe our universe. These parameter values ​​define what we currently know as the Standard Cosmological Model. Some of them are related to the second of the Sandage numbers, then called the deceleration parameter (its value is negative if the cosmological expansion is accelerating, observations indicate).

Cosmologists use this data to determine the state of the universe after the Big Bang and use a cosmological model to predict what the value of the Hubble constant would be. Estimated value of this method H₀= 67,4 ± 0,5 km/s/mpc.

By improving the observation techniques, the error bars of both methods are reduced. And the two ways of measuring become more accurate H₀, have started to give significantly different values. This discrepancy is called the “Hubble tension”: something doesn't match.

To find a solution, you either use new physics that modifies general relativity (which works pretty well everywhere else), or you argue that some of the two types of observations (or their interpretation) are wrong. Or, of course, all of these at once.

Something deeper

The conservative view is that any possible explanation must fall within the framework of our standard cosmological model.

For example, we may not yet fully understand the implications of the large-scale structure in which we are immersed. Laniakia superclusterAs well as our proximity Local Cali.

Laniakea, our local supercluster. Our galaxy (blue dot) is one of about 100,000 galaxies in a supercluster. R. Courtesy of Brent Tully, Helen Courtois, Yehuda Hoffman, and Daniel Pomaret, CC BY

If such a plausible explanation is not ultimately confirmed, we face the possibility that our standard model will require a fundamental revision. And this is a wonderful opportunity for speculation.

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A A recent studyLicia Verde and her collaborators follow a similar path when promising:

“We have to recognize that ΛCDM model , for all its deep connections to fundamental physics and all its triumphs, is ultimately unique. It establishes a solid framework, however, fundamental questions remain unresolved. The elements are dark energy and dark matter This”.

They say it is unreasonable to think that dark matter and energy can be replaced by something more profound, like epicycles or the luminiferous aether in the past.

There are many examples of this kind of dilemma arising in the history of science. We collect some The reinvention of science. Slaying the Dragons of Doctrine and Ignorance. For example, in the 19th century, different entities were proposed to explain the excessive perihelion displacement of Mercury: a planet in Mercury's orbit was named Vulcan, a ring of minor planets, a sufficiently tilted Sun. , as proposed by Simon Newcomb in 1906, is caused by the excitation of the aether, which deviates from Newton's law of gravity in the vicinity of the Sun. All these “dragons” presented at the time were defeated by those who accepted Einstein's principles. General Relativity in 1917.

The “deep one”, for example, requires us to abandon the assumption that dark energy is uniformly distributed throughout space. Alternatively, one could argue that dark matter has some strange properties that we are currently unaware of. Our ignorance of these two great ignorances allows our imaginations to roam free.

All of this is behind Rice's sobering phrase: “Once measurement errors are denied, there is the real and exciting possibility that we have misunderstood the universe.”

This phrase reminds us of Sir Arthur Conan Doyle's famous quote The sign of fourAs Sherlock Holmes says:

“When the impossible is rejected, what remains, however impossible, must be the truth.”Conversation

Vincent J. MartinezProfessor of Astronomy and Astrophysics at the University of Valencia and Member of the Astronomical Laboratory of the same institution, University of Valencia; Bernard JD JonesEmeritus Professor, University of GroningenAnd Virginia L TrimblePhysics and Astronomy, University of California, Irvine

This article was originally published Conversation. to read Original.

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