No-broadcast theorem

Okay, so imagine you have a really cool secret that you need to tell your friends. But, you don't want anyone else to find out about it. So, you come up with a plan to shout the secret out to your friends while they're standing in a circle around you.

Now, let's say your other friends who are not in the circle heard your secret too. This would be really bad because you wanted it to be a secret just between you and your friends in the circle.

This is kind of what happens with particles in quantum physics. Sometimes when particles are close to each other, they can share information with each other in a way that really far away particles can't. Scientists call this "entanglement."

But, if entangled particles are separated by a large distance, like if they're in a different room or even a different planet, scientists have shown that it's impossible for one of the particles to tell the other one about something.

This is called the no-broadcast theorem. It's like saying that your secret can only be passed along to your friends who are standing in the circle around you. It can't be shouted out loud to everyone else who wasn't there. In the same way, particles that are far away from each other can't share their secrets with each other.