Arno Allan Penzias is a very smart man who discovered something really important. He found out that there was a very small amount of energy bouncing around in the air all the time. This energy is called "cosmic microwave background radiation" and it comes from a long time ago when the universe was first starting to form.
Arno and his friend Robert Wilson were working together at a place that studies space and stars called Bell Labs. They were using a really big telescope to explore the sky and listen to the sounds that were coming from the stars. But there was a problem. They kept hearing a weird hissing noise that they couldn't explain.
Arno and Robert tried to get rid of the hissing noise by cleaning the telescope and even getting rid of pigeons that they thought might be making noise on the antenna. But the hissing sound just wouldn't go away.
It took a long time, but Arno and Robert finally figured out that the hissing noise they were hearing was actually the cosmic microwave background radiation. Their discovery helped scientists learn more about how the universe was formed and how it has changed over time.
Arno's discovery was really important, and he even won a Nobel Prize for it! So even though he might be a little hard to understand sometimes, Arno Allan Penzias is a really cool guy who helped us learn more about space and the universe.