Shulou(Shulou.com)11/24 Report--

In a recent paper published in the Royal Astronomical Monthly, researchers proposed a new model: they almost doubled the age of the universe today from 13.8 billion years to 26.7 billion years.

For this result, some people think it is a new scientific discovery, belonging to witness history; others think it is the same as the previous "big bang did not happen" view, just "anti-big bang" people grandstanding. So how should I look at this article?

Since the Webb telescope was launched, research into the early universe has mushroomed. One of the most surprising new findings is that the early galaxies seem surprisingly mature, almost as bright as those around us in the late universe, and have mature galactic structure.

By definition, galaxies grow by "big fish eating small fish," and the early universe should be full of irregular galaxies in the process of merging. But what we actually see is that the galaxies there are very regular and have smooth disks, just like the galaxies around us. In short, what should have been a child-like galaxy showed unusual maturity.

Similarly, there is the question that has long plagued science: how supermassive black holes form. If it were the same way, quasars would not have existed in the early universe, and black holes at the center of galaxies, with masses of billions of times the mass of the sun, would not have existed in our universe. After all, 13.8 billion years is not enough time to synthesize such a huge black hole.

Astronomers have also discovered that some stars are surprisingly old. For example, the famous star Methuselah was calculated to be about 14.5 billion years old, older than the universe itself. A son was born earlier than his father. There must be something wrong with this. Although the star's age fluctuates by 800 million years, it may still be within the age range of the universe of 13.8 billion years, but these phenomena all point to one place-the age of the universe seems to be wrong. If the universe wasn't as young as we think, wouldn't all of these problems be solved?

To know if the age of the universe is correct, first you need to know how it is calculated.

According to various observational data, the expansion of the universe is an indisputable fact, not a purely theoretical prediction. If we know how many times the universe has expanded since its inception and how fast it has expanded during that time, we can calculate how long it has taken, which is the age of the universe.

The expansion speed of the universe, which is mainly reflected in the speed at which celestial bodies move away from us, is also called regression speed. An object (such as a distant galaxy) recedes linearly with its distance from us (v=HD). The farther away an object is from us, the faster it moves away from us. This is known as Hubble-Lemaître's law, also known as Hubble's law.

How do we know how fast an object is moving away from us? This can be judged from the red shift of the light it emits. The existence of redshift indicates that these objects are either moving away from us, that is, Doppler redshift, or there is a strong gravitational field around them, that is, gravitational redshift.

Doppler redshift

Gravitational redshift is obviously impossible: how can all the celestial bodies in all directions escape us? Are we pestilence? Could it be that there was an unknown strong gravitational field surrounding the entire universe? This was even more ridiculous.

Since neither is possible, why does the wavelength of light get longer? For this reason, Zweiki has proposed a hypothesis of "photon fatigue," that is, the photon runs too far, so the wavelength becomes longer and there is a red shift.

The "photon fatigue" hypothesis failed to explain the isotropy of the cosmic microwave background, and it was later felt that it was better to explain it from the perspective of space expansion, so this redshift caused by cosmic expansion was called "cosmological redshift."

From the magnitude of the cosmological redshift, we can calculate how far away the object is from us. The farther away light travels, the longer it takes to reach us, so we see what it looked like long ago. So we can understand how the universe evolved at different times by looking at celestial bodies at different times.

Like the background radiation, it has a redshift of 1100, or about 380,000 years after the Big Bang, which is also the "starting point" of the universe in the traditional Big Bang model. Note: This is not the "odd" of "strange," it is the "start" of "start," the meaning of "start."

Knowing the "limit" of cosmological redshift is equivalent to knowing how many times the universe has expanded, and then finding the specific expansion rate of each period.

An important parameter, the Hubble parameter (H), is required to determine the expansion velocity of space. This involves complicated theoretical calculations. In short, Friedman equations describing the expanding universe can be derived from FLRW metric, general relativity, etc., thus obtaining the relationship between Hubble parameters and matter density.

3H² = 8πGρ

The matter in the universe is mainly composed of baryon matter, dark matter, electromagnetic waves and other radiation, as well as dark energy. Except for the mysterious dark energy, other matter is diluted as the universe expands, so their density is closely related to redshift.

With the density of matter, and this conversion, we know how the Hubble parameter changes with redshift, which is equivalent to knowing the expansion rate of the universe at various times.

H = f(z)

The Hubble parameter for the expansion speed of the universe today is the Hubble constant (H0).

H = f(0) = H0

It can be seen that although Hubble constant is called "constant," it is not completely unchanged on the time scale of the universe. It is more about being the same everywhere in space.

By properly transforming Friedman's equation, it can be seen that the age of the universe is almost the reciprocal of Hubble's constant, so knowing Hubble's constant also knows the age of the universe. This is the approximate way the age of the universe is calculated today.

t = 1 / H0

3 To solve the problem of premature galaxy growth, the researchers did not directly attack the age of the universe, but first introduced an assumption: the assumption that the fundamental physical constants are not constants, but change with time like Hubble's constant.

This seemingly heaven-defying hypothesis wasn't something he just casually said. This hypothesis was first proposed by Paul Dirac, one of the founders of quantum mechanics, who predicted the existence of antimatter, so it is also "well-born."

The researchers are equivalent to taking Dirac as an "endorsement" and then adding a factor to the previous FLRW metric so that basic physical constants such as the gravitational constant can change with time.

Then, through the modified FLRW metric, a dynamic cosmological constant appeared in the new Friedman equation, which predicted that dark energy was no longer a constant but would change with time. The researchers called the model the "covariance coupling constant model (CCC)."

The biggest benefit of this model is that, according to its Hubble constant prediction, our universe has been stretched to 26.7 billion years, which solves the problem of insufficient time mentioned in the opening paragraph.

But there are drawbacks to this model: the galaxies we see in the early universe should be very large, not as small as observed.

To solve this problem, the researchers introduced another hypothesis, the "photon fatigue" hypothesis mentioned earlier.

The researchers believe that tired photons distort images, making them smaller, darker and more blurred. This corresponds to what we observe early galaxies to look like, and the model is called the Fatigue Photon Model (TL).

Although the photon fatigue hypothesis itself has some problems, when combined with the previous coupling constant model, this new model (CCC+TL) can explain many phenomena.

The dilemma facing cosmology today is either a problem with the evolutionary models of galaxies and black holes, or a problem with the evolutionary model of the universe itself.

Usually, most people focus on the former. After all, it is much more feasible to patch galaxies or black holes than to patch models of the universe. Perhaps the existing model only works for the middle and late universe, and it is only necessary to find a model for galaxies or black holes that works for the early universe.

Unlike them, this study looks at the latter, choosing to directly challenge the model of the universe, which is what is worth affirming in the first place. It is not limited to old models, but can think outside the box from a new perspective, providing new ideas for future research.

However, this study is partial to theory, belonging to the "weak theory" obtained by "patching" in order to cater to observed data. Although there are many weak theories like this, the introduction of "constant variability" and "photon fatigue" assumptions into existing theories is inherently risky.

It remains to be seen, for example, whether the theory fits Planck's data well and explains other astrophysical and cosmological observations. After all, it's the same old saying: Extraordinary opinions require extraordinary evidence!

This article comes from Weixin Official Accounts: Linvo Says Universe (ID: linvo001), Author: Linvo

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