Cosmologists find new evidence that our universe has antimatter twins

Cosmologists find new evidence that our universe has antimatter twins

Cosmologists find new evidence that our universe has antimatter twins

The idea of a mirror universe is a common figure of speech in science fiction. A world similar to ours where we can find our evil doppelganger or a version of us that our high school crush asked for.

But the concept of a mirror universe has often been studied in theoretical cosmology, and as a new study shows, it can help us solve problems with the cosmological constant.

Here’s the background — The Hubble constant, or 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, Vesto Slipher, and others. Over the next decades, measurements of this expansion showed a speed of about 70 kilometers/second/Mpc. (Give or take quite a bit.)

Astronomers thought that as our measurements became more accurate, the different methods would come to a common value, but that didn’t happen. In fact, in recent years, measurements have become so accurate that they absolutely do not agree with them. This is also known as the cosmic tension problem.

At this point, the observed values ​​of the Hubble constant are clustered into two groups. Measurements of fluctuations in the cosmic microwave background indicate a lower value, about 67 km/sec/Mpc, while observations of objects such as distant supernovas yield a higher value, about 73 km/sec/Mpc.

Solving the problem of cosmic tension

This image shows the three basic steps astronomers use to calculate how fast the Universe is expanding over time, a value called the Hubble constant.NASA

Something is clearly not right, and theoretical physicists are trying to figure out why. This is where the mirror universe can come in.

Wild ideas tend to fall in and out of popularity in theoretical physics. The idea of ​​the mirror universe is no exception. It was studied quite a bit in the 1990s as a way to tackle the matter-antimatter symmetry problem. 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 was formed as a pair. Our matter universe and a similar antimatter universe. Problem solved. The idea fell out of favor for several reasons, but this new study looks at how it might solve the Hubble problem.

Our universe may have its own antimatter twin that pulls on our own gravitational pull.Shutterstock

How they did it – The team discovered an invariance in what are known as unitless 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 so that all units cancel out so you get the same number no matter which units you use, which is great if you’re a theorist.

The team found that when you adjust cosmological models to match observed expansion rates, several unitless parameters remain the same, suggesting an underlying cosmic symmetry. If you impose this symmetry more broadly, you can scale the gravitational free fall rate and the photon electron scattering rate so that the different methods of Hubble measurement better match.

And if this immutability is real, it implies the existence of a mirror universe. One that would affect our universe through weak gravity.

It should be noted that this study is primarily a proof of concept. It explains how this cosmic invariance might solve the Hubble constant problem, but doesn’t go so far as to prove it is a solution. This requires a more detailed model. But it’s an interesting idea. And it’s good to know that if your evil doppelganger is out there, they can only affect your life through gravity…

This article was originally published on Universe today by Brian Koberlein. Read the original article here.