THis presentation discusses on the possibility of time travel and the takes of famous scientists on it and also that has it been done in past or not?

1. IS IT REALLY POSSIBLE
OR NOT ?

2. WHAT EXACTLY IS TIME ?
Most people think time is constant.
Physicist Albert Einstein showed that it was merely a illusion
Time depending on one’s speed through a space
Einstein declared time as a fourth dimension
Time only provides a coordinate direction which only moves
forward

3. WHAT IS TIME TRAVEL
• Firstly we should get to know that what is TIME TRAVEL?
• Time travel is the concept of movement between certain points of time according to the movement
between different points in space by an object or a person, typically using a hypothetical device known
as time machine, in the form of vehicle or portal connecting distant points in space-time, either to an
earlier time or to an later time, without the need for the time travelling body to experiencing the
intervening period in usual sense.
• Time travel is widely recognised concept in philosophy and fiction.

4. EVIDENCE OF TIME TRAVEL IN OUR HISTORY
700 BC: THE Mahabharata (Ancient India): story
of King Raivata Kakudmi.
Buddhist Pāli Canon mentions the relativity of
time in the Payasi Sutra.
Japanese tale of Urashima Taru.
200s to 400s CE : The Talmud

5. POSSIBILITIES OF TIME TRAVEL
• Most of the scientist agree to the point that time travelling to future is possible but it is uncertain that
time travelling to past is really possible or not
• Forward time travel is possible according to special relativity and general relativity, although making a
body advance or delay more than a few seconds compared to another body is not possible with current
technology.
• As for backwards time travel, it is possible to find solution in general relativity that allow for it, but the
solutions requires the condition that may be not physically possible.
However , travelling to a self-willing point in space time has a very limited support in theoretical physics,
and usually only connected with QUANTUM MECHANICS or WORMHOLES, also known as Einstein-Rosen
Bridges.

6. • It is generally understood that travelling forward or back in time would require a device- a time
machine- to take you there
• Time machine often involves bending the fabric of space-time so far that the lines turn on back
themselves to form a loop, technically known as “closed time like curve.”
• The doctor’s time machine is so called TARDIS, which stands for Time And Relative Dimensions In Space.
A way to travel in time

7. PROBLEMS OF PARADOXES
• If we are able to develop a workable theory for time travel, we would open up the ability to create very
complicated problems called Paradoxes.
• A paradox is a statement that contradicts itself. Possibly the most famous paradox is grandfather
paradox. What would happen if a time traveller went back in time and killed one of his or her ancestors
before the traveller was born?
• If a person killed his/her grandfather how could that person be alive to go back and kill his/her
grandfather? If we could change the past it would create the infinite no. of paradoxes.

8. ALTERNATE THEORY OF TIME TRAVEL
• Another theory regarding time travel brings up the idea of the parallel universes, or alternative
histories.
• Let us consider the grandfather paradox again. Lets say that you travel to meet your grandfather when
he was a boy, so you have travelled to another universe, one that is similar to ours, but has a different
succession of events.

9. • If you killed him so you only killed him in that universe, which is no longer the universe in which you
exist in.
• And if you try to go back to your own time, you may end up with another possible parallel universe and
never be able to get back to the universe you started in.
• The idea here is that every action causes the creation of a new universe and there are infinite number
of universe that exist, i.e. , the theory of multiverse.
• Lets leave this neoteric topic and get Back to our topic

10. • As we discussed earlier, the theory of relativity states that as the velocity of an object nears the speed
of light, time slows down. Scientists have discovered that even at the speeds of the space shuttle,
astronauts can travel a few nanoseconds into future. To understand this, picture two people, person A
and person B. person A stays on earth, while person B takes off in a spacecraft. At take off their watches
at their perfect sync. The closer person B’s spacecraft travel to the speed of light the slower time will
pass for person b{relative to person A}. If person b for just a few hours at 50 % the speed of light and
returns to earth

11. POSSIBLE TIME TRAVEL THEORIES
 The one way of time travel will likely be done by way of natural phenomenon that will transport us
instantly from one point in time to another. These space phenomenon, which we are not even sure exit,
include: black holes
• wormholes
 cosmic strings

12. THE THEORY OF BLACK HOLES(FOR TIME TRAVELLING)

13. • When stars that are more than four times the mass of our sun reach the end of their fuel, they collapse
under the pressure of their own weight. This implosion creates “black holes.” which have gravitational
fields so strong that even light can not escape. Anything that comes in contact with a black hole’s event
horizon will be sucked in. the event horizon of the black hole is its boundary at which nothing can
escape. you can think of the black hole as similar to an ice cream cone.
• It is large on top and tapers into a point, called a singularity. At the singularity the laws of
physics(including newton's law) cease to exist and all matter is crushed beyond recognition. This type of
non-rotating black hole is called a Schwarzschild black hole, named after the German astronomer Karl
Schwarzschild

14. • Another type of black hole, called Kerr hole, is also theoretically possible. Kerr holes are rotating black
holes that could be used as portals for time travel or travel to parallel universes.
• In 1963, mathematician Roy Kerr proposed the first realistic theory for a rotating black holes.in his
theory , dying stars would collapse into a rotating rings of neutrons that would produce sufficient
centrifugal force to prevent the formation of a singularity, Kerr believed that it would be safe to enter
the black hole without being crushed by the infinite gravitational force at its centre. If Kerr holes do
exist, it might be possible to pass through them and exit out of a white hole. A white hole would have
the reverse action of a black hole. So instead of pulling everything into its gravitational force, it would
use some sort of exotic of matter with negative energy to push everything out and away from it. These
white holes would be our way to enter other worlds. Given the little we know about black holes, Kerr
holes may possibly exist. However, some physicist think that it is against physics’ law.

15. Thorne believes there could be another type of tunnel-like structure existing in the universe that could be
used for a time travel portal. Wormholes , also called Einstein-Rosen bridges, are considered to have the
most potential for time travel If they do exist not only they could allow us to travel through time ,they
could also allow us to travel many light years from earth in only a fraction of the amount of time that it
would take us with conventional space travel methods. Worms holes are considered possible based on
Einstein’s theory of relativity ,which states that any mass curves space time.

16. • To understand this curvature you can look AT this picture

17. • According to Einstein , gravity is not a force but a result of the curvature of space time caused by the
uneven distribution of the mass.
• Einstein depicted space as two dimensional plane rather than the four dimensions that actually make
up the space time.
• This 2-d fabric of space-time eventually forms a tunnel that forms a wormhole that looks somewhat like
following figure

18. • So a wormhole act like a shortcut opened through space or something. It is like two holes tied together
by a tunnel.
• Thi tunnel suffers from super gravity and collasp as soon as it opens.so to travel through it we need
something to negate the effect of gravity. And the required substance is so called exotic matter-a
substance with negative mass which repels gravity. The wormhole tunnel is squished and squashed like
the fist of mine. In order to pass through it you need something inside of my hand to oppose the
‘grasping force’ so that I can not squish anymore. And that is the use of exotic matter in time travel.
• So if you stabilize a wormhole with exotic matter injection, teleportation becomes possible.
• According to the theory of relativity,time slows down for objects moving at the speed of light
• So with the help of the time machine discussed before and with the exotic matter you can travel
through wormholes and by travelling in them you can jump forward and back ward in time.

19. • There is another theory that was given by the physicist J. Richard Gott in 1991
• string like objects were formed in the early universe . These string may line the entire length of the universe
and are under immense pressure – millions upon millions of tonnes, which are thinner than an atom, would
generate an enormous amount of gravitational pull on any object that pass near them
• Objects attached to a cosmic string could travel at incredible speeds , and because their gravitational force
distorts space time ,they could be used for time travel
• By pulling two cosmic string close together , or one string close to a BLACK HOLE it might be possible to warp
space time to create space time fabric to create time like curve
• a spacecraft could be turned into a time machine by using the gravity produced by the two cosmic strings to
propel into the past. To do this it would loop around the cosmic string. However there is still much speculation
as to whether these string exist, and they do, in what form. Gott himself said in order to travel back in time
even one year, it would take a loop of string that contained half the mass energy of the entire galaxy. And, as
with any time machine you could no go back farther than the point at which the time machine was created

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A presentation made
With the patronage of
ARJUN SIR
By
Krishna Bansal
&
Kushagra Bhardwaj
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