Space-Time – The space-time
is a peculiar combination of time and space. Time and space together makes a 4th
dimentional spacetime. Gravity and spacetime are linked to one another. Space
time continuum explains this phenomenon defying the physics of space, time and
gravity.
Space-Time
peculiarity explained
Today we are going to talk about Space-Time whether it is real or an illusion. So
the question arises while understanding SpaceTime is that what is time? Is it
related with space?
Before Einstein’s era, scientists believed that space and
time are independent of each other. Neither of them are related in any manner.
So any change in time doesnot effect space and also any change in space doesnot
change time.
According to Newton, Time is absolute irrespective of any
point in space. Which means if anyone spends one hour on earth that means everywhere in
the universe one hour has passed whether anyone is on Mars, Jupiter or travelling
with the speed of light or may be near a black hole.
Now lets understand Space and time separately. Space is
everything we see around us. Each and every object is a part of space. To
denote the position of an object in space, we use the 3-dimentional co-ordinate
system.
Now time is something every one knows that it keeps moving
forward. It is also called time dimension or the fourth dimension. And mixing it with 3-dimentional space, it
creates a 4-dimentional space-time.
But despite of different characteristics, Einstein believed
that Space and time are relative i.e they are related to each other. He said
that time is relative and not absolute, which means that time passes with
different speed depending on the situation and condition. The speed of time for
an object depends on the velocity of the object and also on the gravitational
field of the object. The speed of time slows down with the increase of the
velocity and gravity for the object.
Lets understand this with two examples.
Let us take two planets, our earth and Jupiter. As Jupiter is
much larger than our Earth and also have a larger mass than earth, so the
gravity on Jupiter will be more than that of our earth. So the speed of time on
Jupiter will be slower than on earth. Hence, if a person travels to Jupiter and
lives there then he will live longer than those people on earth as time will
slow down for him.
Again time also depends on speed of the object, so let’s
take two twin brothers. Now if one brother stays on earth and the other goes in
a space mission travelling with high speed with almost the speed of light. Then
what happens, the time for the brother travelling with the speed of light gets
slower. Now when the brother returns back to earth after a couple of years, he
will see that his brother on earth has grown old while his age has just been increased
by two years.
This phenomenon states that time and space are related with
each other. And here the concept of Time dilation and length contraction comes
into play. Now according to Einstein, for every inertial frame of
reference, speed of light is constant. As we reach nearer to the speed of light,
time slows down. If our speed is as fast as that of light then for us time
would seem to stop and also space would seem to adjust itself to time. To
explain this phenomenon a mathematical model was made which is called The Space-Time Continuum.
Physics doesnot see the world as we see. For us every event
in the universe is like a film which keeps moving forward but physics sees this
film in frame by frame reference.
Let’s understand this with the help of an example.
If we throw a pebble in a pond then it creates ripples on
water, for us the event goes simply as a stone is thrown in a pond and because
of which ripples are created. But according to physics, it looks somewhat like a graph where initially no change occurred then after one sec, one ripple had been created, after two sec two ripples had been created and so on. So this graph
makes a cone and now if we want to know the future event of ripples then we
would just have to extend the cone.
This cone is the locus of light through space-time. Now if
we reverse this cone then we get the past events of the cone. This cone is
called Future light cone.
This cone helps us to understand our universe. A great
example of this is the Big Bang theory. As we can understand how the past of
any planet or event was and also we can know what the future of the planet or
event will be by just calculating its position in the spacetime graph. And due
to this Space-Time concept we can understand gravitation clearly.
Watch a video related to this topic here- http://dai.ly/x6p9axp
The Mystery of
spacetime and gravity defined
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