According to a new study by a Canadian physicist, the age of the universe may be as old as 26.7 billion years. This hypothesis challenges the dominant cosmological model and is very difficult to prove, but it could answer some of the problematic questions about the early universe.
For years, astrophysicists have been calculating the age of our universe by measuring the time since the Big Bang and studying the oldest stars based on the redshift of light from distant galaxies. They did it this way: all Type Ia supernovae (reliably identifiable from the spectrum) have close flash energies, but their observed brightnesses are different because they are at different distances from Earth. By comparing the brightness of these "standard candles of cosmology," it is possible to understand how far away from us those galaxies that include these supernovae are.
Astronomers then discovered that objects defined as distant by this method appear very red compared to similar objects defined as close (cosmological redshift). To explain this oddity, they first proposed the "tired light" model - that photons lose energy with distance, making them more "red" (i.e., longer-wavelength). This explanation did not work for a number of reasons, including, for example, the fact that supernovae flares in distant regions of the Universe last, in the opinion of astronomers, longer than in close ones.
Therefore, instead of the "tired light" hypothesis, the increase in redshift with distance was explained by the general theory of relativity. According to it, redshift is a normal outcome for a photon traveling through space, which is expanding. This explained why supernovae outbreaks in the early Universe went longer than in the near Universe: because of the stretching of photons from distant supernovae astronomers observed a seeming slowing of time for events in the early Universe. According to calculations within this approach, the observed redshift from distant galaxies gives a well-defined rate of their distance from each other due to the expansion of the Universe - about 70 kilometers per second per megaparsec. If we divide the distance between distant galaxies and us by this value, we get 13.8 billion years - it turns out that the Big Bang, which gave birth to the present Universe, happened just then.
Difficulties with age
However, in the last decade, data poorly compatible with the classical model of the development of the Universe began to accumulate. There are some very ancient stars, such as Methuselah (HD 140283) and others that should have formed 13.5 billion years ago. Meanwhile, until now it was thought that many hundreds of millions of years must have passed between the Big Bang and the formation of the first stars. Scientists have also discovered some galaxies from the early Universe that are at an advanced stage of cosmic evolution: although they are visible to us as they were only a few hundred million years after the Big Bang, they contain relatively heavy element-rich stars that require a long time of stellar evolution to form.
To resolve this contradiction, Professor Rajendra Gupta (Rajendra Gupta) from the University of Ottawa (Canada) proposed to combine the hypothesis of "tired light" with an explanation of the red shift through the expansion of the universe in the framework of the theory of relativity. The work on this topic, the scientist published in the journal Monthly Notices of the Royal Astronomical Society.
According to the astrophysicist, in conjunction with the model of tired light make sense and hypotheses that the fundamental physical constants governing the interaction between particles can change over time. Including those constants from which the cosmological redshift and the age of the universe are calculated.
If the constants do change in this way, then the timescales for the formation of early galaxies observed at large redshifts can be extended from a few hundred million years to several billion years. This gives more time for galaxies to evolve and for old stars to appear in the early universe. In the end, Gupta suggested that the probable age of the universe is 26.7 billion years, which is about twice the current estimate.
New answers, new questions
In his approach, Gupta tries to remove the contradictions between the small age of the universe observed within relativity theory (13.8 billion years) and the very mature galaxies that astronomers have discovered in the last decade. Say, the galaxy HD1 - 13.463 billion years old, it was formed only 324 million years after the Big Bang. And yet it's still very bright, at the level of many modern galaxies. Current mainstream cosmology cannot explain how enough stars needed to form a bright galaxy could have appeared in such a short time. Against this background, it is not surprising that Gupta turned to the late 1920s tired light hypothesis.
However, his work, first of all, explained not all weak points of "tired light". For example, if photons "tired" with distance, the spectrum of relic radiation (from the moment of the Big Bang) would look quite different from what it does now. Theoretically, by arbitrarily changing the physical constants (based on Gupta's assumption that they change with time), one can try to explain this too, but here comes the "second".
The second weakness of Gupta's approach is that it is extremely difficult, if not impossible, to test. If we assume that the physical constants in the early universe were changing, we can explain almost any observation from it. But we cannot confirm whether they were changing in the way described, because experiments in the early universe are not available. Consequently, Gupta's hypothesis is weakly testable, which puts it on the verge of being unscientific.
There are other attempts to explain the existence of very mature galaxies in the very early Universe - on the basis of relativity theory alone and without involving exotic hypotheses like "tired light" or time-varying physical constants. According to the proponents of this view, our Universe is cyclic, undergoing contraction followed by expansion.
The most complete theory of such a series is set forth in the book "Oscillating Universe" by physicist Nikolai Gorkavoy, published in 2023. Within its framework, the age of the Universe also exceeds 13.8 billion years (so much has passed only since the last Big Bang), but not twice, but a huge number of times.