If we convert all the atoms in the universe into energy, there would be no universe left. Energy and matter are equivalent, as expressed by Einstein’s famous equation E=mc^2. This means that if all the matter in the universe were converted into energy, the total amount of energy in the universe would be the same, but it would be in a different form. The universe would essentially be a giant ball of energy, with no matter left to form stars, planets, or anything else.

This would be a very different universe than the one we live in today. There would be no life, no stars, no planets, and no galaxies. The universe would be a very dark and empty place.

It is important to note that this is just a hypothetical scenario. There is no way to actually convert all the atoms in the universe into energy. However, it is an interesting thought experiment that can help us to understand the relationship between matter and energy.