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: Despite digital revolution, distance still matters

Related Stories

Despite digital revolution, distance still matters

July 18, 2018

Even when people have well-connected social networks beyond their home cities and across state lines, they are still most frequently interacting with people who are very geographically near.

Team creates high-fidelity images of Sun's atmosphere

July 18, 2018

In 1610, Galileo redesigned the telescope and discovered Jupiter's four largest moons. Nearly 400 years later, NASA's Hubble Space Telescope used its powerful optics to look deep into space—enabling scientists to pin down ...

Molecular clock could greatly improve smartphone navigation

July 16, 2018

MIT researchers have developed the first molecular clock on a chip, which uses the constant, measurable rotation of molecules—when exposed to a certain frequency of electromagnetic radiation—to keep time. The chip could ...

Cooling buildings worldwide

July 12, 2018

About 40 percent of all the energy consumed by buildings worldwide is used for space heating and cooling. With the warming climate as well as growing populations and rising standards of living—especially in hot, humid regions ...

Sensor detects nanoparticles with field of bouncing light

July 11, 2018

Technology created by researchers at the Okinawa Institute of Science and Technology Graduate University (OIST) is literally shedding light on some of the smallest particles to detect their presence – and it's made from ...

Recommended for you

Unusual sound waves discovered in quantum liquids

July 20, 2018

Ordinary sound waves—small oscillations of density—can propagate through all fluids, causing the molecules in the fluid to compress at regular intervals. Now physicists have theoretically shown that in one-dimensional ...

A phonon laser operating at an exceptional point

July 20, 2018

The basic quanta of light (photon) and sound (phonon) are bosonic particles that largely obey similar rules and are in general very good analogs of one another. Physicists have explored this analogy in recent experimental ...

Did a rogue star change the makeup of our solar system?

July 20, 2018

A team of researchers from the Max-Planck Institute and Queen's University has used new information to test a theory that suggests a rogue star passed close enough to our solar system millions of years ago to change its configuration. ...

Houseplants could one day monitor home health

July 20, 2018

In a perspective published in the July 20 issue of Science, Neal Stewart and his University of Tennessee coauthors explore the future of houseplants as aesthetically pleasing and functional sirens of home health.

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.