Physics
What drives the universe's expansion?
Quick fact
The universe has been expanding since the Big Bang approximately 13.8 billion years ago.
Why this is interesting
The galaxies around us are moving apart because the universe itself is growing.
Read the full explanation
Understanding What drives the universe's expansion?
Scientists observe expansion by measuring how light from distant galaxies is shifted toward longer wavelengths, known as redshift.
A deeper explanation
The expansion of the universe is described by modern cosmology and Einstein's theory of general relativity. While gravity pulls matter together locally, the large-scale structure of space continues to expand. The discovery that expansion is accelerating led to the concept of dark energy.