If we know how big the observable Universe is, why can't we figure out how big the unobservable part is?

In 1916, Albert Einstein discovered that his theory of general relativity predicted the existence of gravitational waves — ...

The exact size of the whole universe is unknown, but estimates put it at around 23 trillion light-years in diameter. Other cosmologists say that the whole universe may simply be infinite.

What does the entire observable universe look like? Not exactly like this–but it’s a pretty (and fascinating) picture. The illustration, based on logarithmic maps from Princeton researchers ...

How can the behavior of elementary particles and the structure of the entire universe be described using the same mathematical concepts? This question is at the heart of recent work by the ...

The universe is about 14 billion years old, but the most distant galaxies are much further than 14 billion light years. How can that be? In this week’s “Ask a Physicist,” we’ll find out.

The age and size of the universe are, of course, interrelated, and both depend critically on the Hubble constant.

And yet, that’s just a tiny speck in the entire Universe.The Solar System, with all its planets and dwarf planets, seems vast in comparison to the Earth’s size, but it is only a small part of ...

Have you ever wanted to hold the universe in the palm of your hand? Well, now you can… As long as you have the file storage space for it. An international team of scientists has come together to ...

Scientists propose that "stupendously large" black holes between the size of a solar system and an entire galaxy could be hiding throughout the universe.