For thousands of years, human beings have believed the night sky might hold the key to our existence.

And yet the universeEverything. Including all of time and space and its contents. has not yet been able to answer many of our biggest questions. Three years ago scientists in the USAThe United States of America is a country in North America. It has a population of 329 million. created the Dark Energy Spectroscopic Instrument (DESI). They hoped it could answer one of the most difficult of all these questions: dark energyAn unknown form of energy causing the expansion of the universe to accelerate..

By the 1900s, scientists knew that the universe was getting bigger. However, they thought that gravityAn invisible force that pulls objects towards each other. Earth's gravity keeps us on the ground and makes things fall. It is less strong on Mars. should be making this processA way of doing things. slow down. Instead, the universe was getting bigger at an even faster rate.

Scientists thought this must be caused by something that could work against gravity. They gave it the name "dark energy".

Understanding how dark energy works is key to knowing what the future holds for our universe.

But between now and 2030 we might yet discover still stranger things about dark energy. The first results from DESI suggest much of what we thought we knew about it could be wrong. One group of scientists even argues that it does not really exist.

Will we be astonished by how little we know now?

Yes! So far, the results of DESI are turning over everything we thought we knew about dark energy. By 2030, we might have totally new ideas about how the universe works.

No! Most scientists still think that dark energy exists. In fact, it could be that by 2030, instruments like DESI will have found out that everything we think we know now is in fact true.