(ORDO NEWS) — The idea of a mirror universe is a common image in science fiction. A world similar to ours, where we could find our evil doppelgänger or a version of ourselves that actually invited our high school crush.
But the concept of a mirror universe is often studied in theoretical cosmology, and as new research shows, it can help us solve problems with the cosmological constant.
The Hubble constant or the Hubble parameter is a measure of the rate at which our universe is expanding. This expansion was first demonstrated by Edwin Hubble using data from Henrietta Leavitt, Westo Slifer, and others.
Over the next few decades, measurements of this expansion stopped at about 70 (km/sec)/Mpc. Give or take very little. Astronomers expected that as our measurements became accurate, the various methods would come to a common value, but this did not happen.
In fact, over the past few years, the measurements have become so accurate that they are clearly at odds. This is sometimes called the cosmic stress problem.
At the moment, the observed values of the Hubble constant are grouped into two groups. Fluctuation measurements of the cosmic microwave background indicate a lower value, around 67 (km/sec)/Mpc, while observations of objects such as distant supernovae give a higher value, around 73 (km/sec)/Mpc.
Something is clearly not adding up, and theoretical physicists are trying to figure out why. This is where the mirror universe can appear.
Wild ideas tend to fall out of favor in theoretical physics. The idea of a mirror universe is no exception.
It was studied quite a lot back in the 1990s as a way to solve the symmetry problem of matter and antimatter.
We can create matter particles in the lab, but when we do that, we also create antimatter particles. They always come in pairs. So, when particles formed in the early universe, where did all their antimatter siblings go?
One idea was that the universe itself formed as a pair. Our universe of matter and a similar universe of antimatter. Problem solved. This idea fell out of favor 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.
In principle, you can combine measured parameters in such a way that all units of measure cancel out, giving you the same no matter what units you use, which is great if you’re a theorist.
The team found that when you tweak cosmological models to match observed expansion rates, some dimensionless parameters remain unchanged, suggesting an underlying cosmic symmetry.
Applying this symmetry more broadly, one can scale the gravitational free fall rate and the photon-electron scattering rate 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. One that will affect our universe through a weak gravitational pull.
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 go so far as to prove that it is a solution.
This would require 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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