The simplest
definition of space-time is “space-time is any mathematical model that combines
space and time into a single interwoven continuum” Space-time is a difficult
concept to understand. Below are the 10 must-know facts about space-time.
1. Time passes
more slowly in the orbit around earth than on the surface of the earth. This
means that returning astronauts from space arrive home slightly younger.
2. The universe
has been expanding for 13.7 billion years, this produces a cosmic horizon in space, where the light has not reached
earth yet from objects further away from 12 to 13 billion light-years.
3. The shortest
moment in time is defined by thePlanck time,
which is 5.391 06(32) × 10−44 s. It is determined by the Planck’s
constant, the gravitational constant and speed of light.
4. Matter
determines how space-time curves. General Relativity explains how a spaceship
travelling any speed slows down as it passes through a gravitational field,
such as passing the planet Earth.
5. NASA’s Voyager
1 is at the edge of our solar system, it is at the distance of 19 billion
kilometers away and it takes over 16 hours to send or receive a radio signal.
6. Time hasn’t always existed, the theory of relativity
suggests before the Big bang, 13.74 billion years ago, time and space didn’t
exist.
7. The fundamental
description of the universe does not take into account Past, Present and
Future. According to the special theory of relativity, there is no such thing
as future or the past, everyone’s time frame is relevant to each other.
8. Atomic clocks are
the most accurate clocks ever built. Some clock can measure a single vibration
in a single atom of Mercury.
9. Time on Earth
is actually slowing down. This is due to the tidal friction of Sun and the
moon. So the day is lengthening by 1.7 milliseconds each century.
10. The Cosmic
Microwave Background is the remnant of the hot Big Bang that fills the
entire sky. Certain fluctuations in the temperature on Cosmic Microwave
Background could give us clues about other universes.
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