What Science Says About Time Travel

It may surprise you that physicists don't understand time. Travel into the future appears plausible now.

How Time Works

Traveling back in time to meet our great-great-great grandparents seems implausible.

How Time Works

Albert Einstein helped us grasp time travel. His relativity theory described space, time, mass, and gravity.

Albert Einstein

For Einstein, time was relative. Relativity causes time to flow differently. Situations can hasten or slow time.

The Relativity Theory

Its ability to speed up or slow down suggests time travel with real-world consequences.

Relative Time

Time passes faster with speed, but for the effect to be evident, you must travel at the speed of light.

Speed Of Light

Similarly, time moves slower in an extreme gravitational environment, such as a black hole.

Pull Of Gravity

Sky clocks tick faster than Earth clocks. Thus, the ones in the sky must be regularly adjusted for precision. If not, your map app may be six miles (10 km) off per day!

Adjust Clock

Traveling into the future is conceivable with relativity. Whether moving at the speed of light or in a strong gravitational environment, subjective time is brief.

Future Travel

Relativity does allow for backwards time travel, however this is still in the theoretical stage.

Reverse travel

One 1949 study by Kurt Gödel suggested a closed time-like curve, where space and time loop back on itself, could allow past time travel.

Closed-circle loop theory

No closed-circle loop exists in the universe, which undermines this notion. Pure theory.

Closed-circle loop theory