What is time?

April 13, 2005

The concept of time is self-evident. An hour consists of a certain number of minutes, a day of hours and a year of days. But we rarely think about the fundamental nature of time.
Time is passing non-stop, and we follow it with clocks and calendars. Yet we cannot study it with a microscope or experiment with it. And it still keeps passing. We just cannot say what exactly happens when time passes.

Time is represented through change, such as the circular motion of the moon around the earth. The passing of time is indeed closely connected to the concept of space.

According to the general theory of relativity, space, or the universe, emerged in the Big Bang some 13.7 billion years ago. Before that, all matter was packed into an extremely tiny dot. That dot also contained the matter that later came to be the sun, the earth and the moon – the heavenly bodies that tell us about the passing of time.

Before the Big Bang, there was no space or time.

“In the theory of relativity, the concept of time begins with the Big Bang the same way as parallels of latitude begin at the North Pole. You cannot go further north than the North Pole,” says Kari Enqvist, Professor of Cosmology.

One of the most peculiar qualities of time is the fact that it is measured by motion and it also becomes evident through motion.

According to the general theory of relativity, the development of space may result in the collapse of the universe. All matter would shrink into a tiny dot again, which would end the concept of time as we know it.

“Latest observations, however, do not support the idea of collapse, rather inter-galactic distances grow at a rapid pace,” Enqvist says.

Source: University of Helsinki

Explore further: New type of electron lens for next-generation colliders

Related Stories

New type of electron lens for next-generation colliders

October 18, 2017

Sending bunches of protons speeding around a circular particle collider to meet at one specific point is no easy feat. Many different collider components work keep proton beams on course—and to keep them from becoming unruly.

Plasma optic combines lasers into superbeam

October 17, 2017

Since its introduction in the 1977 film "Star Wars," the Death Star has remained one of science fiction's most iconic figures. The image of Alderaan's destruction at the hands of the Death Star's superlaser is burned into ...

Gravitational waves: Why the fuss?

October 16, 2017

Great excitement rippled through the physics world Monday at news of the first-ever detection of two ultra-dense neutron stars converging in a violent smashup.

Autonomous driving at the bus depot

October 12, 2017

Autonomous driving is an important element of new mobility concepts, not only in the private car sector. A study of Karlsruhe Institute of Technology (KIT), KIT's Research Center for Information Technology (FZI), and Stuttgarter ...

Recommended for you

Metacognition training boosts gen chem exam scores

October 20, 2017

It's a lesson in scholastic humility: You waltz into an exam, confident that you've got a good enough grip on the class material to swing an 80 percent or so, maybe a 90 if some of the questions go your way.

Two teams independently test Tomonaga–Luttinger theory

October 20, 2017

(Phys.org)—Two teams of researchers working independently of one another have found ways to test aspects of the Tomonaga–Luttinger theory that describes interacting quantum particles in 1-D ensembles in a Tomonaga–Luttinger ...

Dawn mission extended at Ceres

October 20, 2017

NASA has authorized a second extension of the Dawn mission at Ceres, the largest object in the asteroid belt between Mars and Jupiter. During this extension, the spacecraft will descend to lower altitudes than ever before ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.