SAT by ShreySaxena

2. What is Space and Time?
Spacetime is a mathematical model that combines
the three dimensions of space and one dimension
of time into a single four-dimensional manifold.
Spacetime diagrams can be used to visualize
relativistic effects, such as why different observers
perceive differently where and when events occur.
Until the 20th century, it was assumed that the
three-dimensional geometry of the universe (its
spatial expression in terms of coordinates,
distances, and directions) was independent of one-
dimensional time.

3. NEWTON'S CONCEPT OF SPACE AND TIME
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4. EINSTEIN'S CONCEPT OF SPACE AND
TIME
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5. RELATIVE SPACE
Relative space contrasts with absolute space, wherein location is understood with respect to an
independent frame of reference such as a coordinate system. The dimensions of absolute space
are fixed and immovable, whereas relative space is a movable dimension. The difference
between absolute and relative space has been a long-running debate in physics.

6. RELATIVE TIME
A relative time simply tells you that one event or object is older or younger than another. For
example, the fact that you were born after your mother fixes your relative ages. An absolute
time scale fixes units of time to events or objects. If you were born in 1990 and your mother in
1965, then you are 25 years younger than your mother.

7. THEORY OF RELATIVITY AND SPECIAL RELATIVITY

8. SPEED OF LIGHT
The speed of light in vacuum, commonly denoted c, is a universal physical constant that is
exactly equal to 299,792,458 meters per second. According to the special theory of relativity, c is
the upper limit for the speed at which conventional matter or energy can travel through space.
The Speed of Light = 299 792 458 m / s

9. Time Dilation
In physics and relativity,
time dilation is the
difference in the elapsed
time as measured by two
clocks. It is either due to a
relative velocity between
them or to a difference in
gravitational potential
between their locations.
When unspecified, "time
dilation" usually refers to
the effect due to velocity.

11. Time travel is the concept of
movement between certain
points in time, analogous to
movement between different
points in space by an object or
a person, typically with the use
of a hypothetical device known
as a time machine. Time travel
is a widely recognized concept
in philosophy and fiction,
particularly science fiction. The
idea of a time machine was
popularized by H. G. Wells'
1895 novel The Time Machine.

12. As for backward time travel, it is possible
to find solutions in general relativity that
allow for it, such as a rotating black hole.
Traveling to an arbitrary point in
spacetime has very limited support in
theoretical physics, and is usually
connected only with quantum mechanics
or wormholes.

13. Is Time Travel Possible?
According to NASA, time travel is possible, just not in the way
we might expect. Albert Einstein’s theory of relativity says time
and motion are relative to each other, and nothing can go
faster than the speed of light, which is 186,000 miles per
second. Time travel happens through what’s called “time
dilation.”

14. Dark matter is a hypothetical form of matter thought to account for
approximately 85% of the matter in the universe.

15. DARK ENERGY
Dark Energy is a hypothetical form of
energy that exerts a negative,
repulsive pressure, behaving like the
opposite of gravity. It has been
hypothesised to account for the
observational properties of distant
type Ia supernovae, which show the
universe going through an accelerated
period of expansion.