Are there stars made of antimatter?


Just a couple of days ago, I was sent a question in the title of this article. Let’s figure it out together.


The difference between particles and antiparticles is only in the signs of interactions (electric charge, quantum numbers, etc.). «Mirror reflections» are not only for the electron, but in general for the majority of particles. If an antiparticle collides with an ordinary particle, then their

Antimatter may well consist of ordinary objects and chemicals (for example, antihydrogen, antihelium, etc.). And of course, there are no physical barriers to the fact that whole stars or even galaxies consist of antimatter.

They just don’t. We can say with a great deal of confidence that there are no stars of antimatter in the observable universe, just as there are no regions where there would be more antimatter than matter.

One of the main and common misconceptions about space is that the interstellar medium is a vacuum in which there is nothing. Emptiness. In fact, this is not the case. The cosmos is filled with an enormous amount of matter. Hydrogen-helium plasma, heavier elements, polycyclic aromatic hydrocarbons, even organic substances — all this is in abundance in the interstellar medium.

From a practical point of view, we consider this to be a vacuum, but in general, strictly speaking, this is not entirely true. On average, there are about a million atoms of matter per cubic centimeter of the interstellar medium.

Now let’s imagine a star, or a nebula, or a galaxy, or a cluster of galaxies made of antimatter. This object will inevitably be surrounded by ordinary matter. There is just a huge amount of tons of matter around him just waiting for an opportunity to collide with antiparticles and annihilate.

As a result, if such an object existed, it would be incredibly bright (by the number of high-energy photons) due to the constant annihilation of matter and antimatter along its edges.

If, for example, somewhere in our galaxy a star of antimatter is placed, this star will easily become the brightest (in terms of the number of high-energy photons) object in our galaxy. There is no chance that we would have missed such an object with the telescopes now available. The same goes for other galaxies. Any such object would stand out very strongly from the background of others.

Considering that we have never observed anything like this, it can be argued with great confidence that there are no significant antimatter objects in the observed Universe, and insignificant ones have long been annihilated.

For some reason, the observed universe is almost entirely composed of matter, and antimatter is practically not found in it. This paradox is called