(ORDO NEWS) — The idea of a mirror universe is a common device in science fiction. A world similar to ours, where we can find our evil doppelgänger or a version of us that actually asked our high school girlfriend out on a date.
But the mirror universe concept is often studied in theoretical cosmology, and a new study shows it could help us solve problems with the cosmological constant.
The Hubble constant, or the Hubble parameter, is a measure of the expansion rate of our Universe. This expansion was first demonstrated by Edwin Hubble using data from Henrietta Leavitt, Vesto Slifer, and others. Over the next few decades, measurements of this expansion stopped at about 70 km/sec/Mpc.
Plus or minus quite a bit. Astronomers believed that as the accuracy of measurements improved, various methods would come to a single value, but this did not happen.
In fact, over the past few years, the measurements have become so precise that they are completely inconsistent with each other. This is sometimes called the cosmic stress problem.
At the moment, the observed values of the Hubble constant are divided into two groups. Measurements of fluctuations in the cosmic microwave background indicate a lower value of about 67 km/sec/Mpc, while observations of objects such as distant supernovae give a higher value of about 73 km/sec/Mpc.
Something clearly doesn’t add up, and theoretical physicists are trying to figure out why. This is where the mirror universe can appear.
In theoretical physics, wild ideas tend to fall and lose popularity. The idea of a mirror universe is no exception. In the 1990s, it was quite actively studied as a way to solve the problem of the symmetry of matter and antimatter.
We can create matter particles in the lab, but when we do that, we also create antimatter particles. They always form pairs. So, when particles formed in the early universe, where did all their antimatter siblings go?
One idea is that the universe itself formed as a pair. Our universe is made of matter and the same universe is made of antimatter. Problem solved. This idea has been dropped for various reasons, but a new study looks at how it could solve the Hubble problem.
The team found invariance in the so-called dimensionless parameters. The best known of these is the fine structure constant, which has a value of about 1/137. Basically, you can combine measured parameters in such a way that all units cancel out, giving the same number no matter what units you use, which is great if you’re a theorist.
The team found that when you tune the cosmological models to match observed expansion rates, several dimensionless parameters stay the same, suggesting an underlying cosmic symmetry.
By imposing this symmetry more broadly, one can scale the gravitational free fall velocity and the photon and electron scattering velocity so that the various Hubble measurement methods are in better agreement. And if this invariance is real, it implies the existence of a mirror universe. Which could influence our Universe through a weak gravitational attraction.
It should be noted that this study is mainly a proof of concept. It shows how this cosmic invariance can solve the problem of the Hubble constant, but does not prove that this solution is possible. This requires a more detailed model.
But it’s an interesting idea. And it’s good to know that if your evil twin is somewhere nearby, it can only affect your life gravitationally…
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