The age of the
Universe has been a hotly debated topic for decades. In recent years, a consensus has emerged, and most scientists now believe our world is 13.797 billion years old. However, in a paper published by ScienceAlert, researchers from the University of Ottawa have come up with a bold hypothesis, suggesting that it may actually be twice as old.
If there is still no clear and definitive answer to this question, despite long discussions by experts, it is because it is extremely difficult to find reliable evidence on which to rely.
Today, the most convincing approach is based on observations of the oldest stars, interpreted through the work of astrophysicist Vesto Slifer.
In the 1910sSlyfer was the first to discover the redshift of galaxies, a phenomenon that has become one of the cornerstones of cosmology.
Despite the differences, the redshift concept is often approximated by the Doppler effect to explain it. The latter explains, among other things, changes in the sound of a passing Formula 1 car or an ambulance siren.
You've probably already noticed that by listening carefully, you can guess the movement of a vehicle relative to your ears by the sound of the engine. Formula 1 noise gets louder as you get closer and quieter as you get farther away. This is because sound waves seem to "stretch" as they move away from the observer; since the pitch of a sound is directly related to its frequency, this results in a change in perception.
Although the Doppler effect is not technically the cause of the displacement used in cosmology, its interpretation is based on a similar principle. The difference is that instead of sound, astronomers use a different type of waves - electromagnetic waves, i.e. light.
We know from the work of Edwin Hubble and Georges Lemaitre that the universe is constantly expanding. This means that other celestial bodies are moving away from us. However, when radiation emanating from stars spreads across the universe over vast distances, its wavelength changes. Just as the sound of a siren becomes lower, this causes a red shift in the light spectrum that reaches us.
By determining the value of this redshift, we can obtain data on the motion of stars. Since the
expansion of the Universe is accelerating with time, we can infer their age: the greater the redshift of light, the older the object, the source of that light.
This approach is widely used because it gives stable results. However, there are significant shortcomings in this model, and researchers are still puzzled by the cases of some objects.
Photo:focus.ua
For example, according to the redshift method, the oldest galaxies recently discovered by the
James Webb Space Telescope are about 13.4 billion years old, which roughly corresponds to 300 million years after the
Big Bang, a period that corresponds to the dawn of the known universe. However, they sometimes show features that, according to current cosmological models, should only appear after a few billion years, which raises doubts among experts.
The key to explaining these observations is based on a concept formulated in the last century. To defend the idea of a static universe without expansion,
Albert Einstein introduced the concept of "tired light." This concept states that light can lose energy in proportion to the distance traveled.
Later, the famous Swiss astrophysicist Fritz Zwicky picked up on this hypothesis. He suggested that the observed redshift might be a consequence of this "fatigue" of light rather than the expansion of the universe. However, this theory was clearly inconsistent with many observations and was eventually rejected by the scientific community, which supported Hubble's idea.
To the rescue comes the team of Rajendra Gupta, a researcher at the University of Ottawa. These scientists have come up with a rather bold idea: according to them, the two concepts are not necessarily incompatible. A hybrid model could explain the observed inconsistencies. "By allowing the two theories to coexist, we can reinterpret the redshift as a hybrid phenomenon and not just a consequence of the expansion of the universe," Gupta explains.
To connect these concepts, Gupta drew on another idea formulated in 1982 by the Nobel physicist Paul Dirac. With an important quantum physics equation that today bears his name, Dirac introduced the concept of a "coupling constant."
Briefly, these constants describe the interactions between the forces that govern the behavior of subatomic particles. They exist for all observable forces in the universe. But, contrary to what their name implies, these "constants" can evolve over time.
This brings us to the heart of Gupta's theory. According to him, changes in these constants can affect the behavior of light. However, this is what all estimates of the age of the Universe are based on.
This would have important consequences. If this is true, all our calculations on this could be wrong! And this difference could be significant, depending on the model proposed by Gupta's team.
The universe may be nearly twice as old as it is believed to be today.
"Our new model stretches the formation of galaxies by billions of years, resulting in an age of the universe of 26.7 billion years, rather than the 13.7 billion years previously assumed," he explains in a statement.
Obviously, this is just an ambitious theory at the moment. It should be compared with concrete observations to see if it is indeed compatible with observed reality. However, the idea is also attractive because it would remove many of the ambiguities of current cosmological models.
Therefore, this work and the work of other teams dealing with this topic should be followed closely. However, we should not be in a hurry. In practice, it will take many years of observation to confirm or deny such a revolutionary assumption.
In any case, whether or not this new model is correct, it represents a new opportunity to rethink the limits of existing theories. This is an important step for the future of cosmology and science in general. After all, only by regularly questioning these advances will humanity be able to unlock the deepest secrets of our world.
We can only hope we'll still be here to take advantage of it when researchers finally piece together the vast mystery of the universe!