In this presentation, I am discussing about possibilities and Including various concepts and Theories related to Time Travel. I HOPE YOU ALL WILL LIKE THIS PRESENTATION

1. TIMETRAVEL:
Concepts andTheories
SUBMITTED BY:-
ANAND BHANDARI

2. INTRODUCTION
 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 using a hypothetical device known as a time
machine.

3. POSSIBILITYOF
PASTAND
FUTURETIME
TRAVEL
 It is uncertain if time travel to the past is physically possible.
 Forward time travel, outside the usual sense of the perception of time,
is an extensively- observed phenomenon and well-understood within
the framework of special relativity and general relativity.

4. TIMETRAVEL IN
PHYSICS
Time travel to the past is theoretically
possible in certain general relativity
spacetime geometries that permit traveling
faster than the speed of light, such as
cosmic strings, traversable wormholes, and
Alcubierre drive.

5. POSSIBILITIES
OFTIMETRAVEL
Travelling in time could be possible in the following four
ways:
1. Wormholes
2. Cosmic string
3. Supermassive black hole
4. Travelling at the speed of light ……and time machine is
what actually based on above hypothesis

6. WORMHOLES
 A wormhole (or Einstein–Rosen bridge) is a speculative structure
linking separate points in spacetime.
 A wormhole would allow an object to travel from one point to another
faster than the speed of light.
 Problem: No wormhole has ever been discovered, and even if it was, it
would be far too small for scientists to manipulate for the purposes of
time travel

7. COSMICSTRINGS
 Described as one-dimensional "cracks in the universe" and some of the
strangest structures observed by cosmologists.
 The approach of two such strings parallel to each other, will bend
space-time so vigorously and in such a particular configuration that [it]
might make time travel possible .
 Problem: Again, cosmic strings only exist only in theory.

8. SUPERMASSIVE
BLACK HOLE
 A black hole is a region of spacetime exhibiting such strong gravitational
effects that nothing—not even particles and electromagnetic radiation such
as light—can escape from inside it.
 If a spaceship were to orbit a black hole, those on board would only
experience eight minutes of time for every 16- minute orbit.
 Problem : It's a long way away and it doesn't even take us very far into the
future.

9. TRAVELLINGAT
THESPEEDOF
LIGHT
 We all know that the speed of light is 3x10^8 m/s.
 In Einstein's special theory of relativity, “time” as a universal concept.
Instead, time passes differently for different observers, depending on the
observers' motion and - more importantly, speed.
"If you go fast, your clock runs slow relative to people who are still’’
Problem: According to the laws
of physics, nothing can travel as
fast as the speed of light – let
alone a spaceship. Even the
Large Hadron Collider, the
strongest particle accelerator
in the world, can't make
protons move that fast.

10. TIMETRAVEL IN
HISTORYAND
FICTION
Time travel in fiction: Time travel themes in science fiction and the
media can generally be grouped into three categories:
 immutable timeline;
 mutable timeline;
 and alternate histories
History of the time travel concept: In
Hindu mythology, the Mahabharata
mentions the story of King Raivata
Kakudmi, who travels to heaven to meet
the creator Brahma and is surprised to
learn when he returns to Earth that many
ages have passed.

11. NO -SIGNALING
PRINCIPLE
 When a signal is sent from one location and received at another
location, then as long as the signal is moving at the speed of light or
slower, the mathematics of simultaneity in the theory of relativity show
that all reference frames agree that the transmission-event happened
before the reception-event.
When the signal travels faster than
light, it is received before it is sent, in
all reference frames. The signal could
be said to have moved backward in
time. This hypothetical scenario is
sometimes referred to as a tachyonic
antitelephone.

12. ABSENCEOF
TIME
TRAVELLERS
FROMTHE
FUTURE
 The absence of time travelers from the future is a variation of the Fermi
paradox. As the absence of extraterrestrial visitors does not prove they
do not exist, so does the absence of time travelers not prove time travel
is physically impossible; it might be that time travel is physically possible
but is never developed or is cautiously used.
 Several experiments have been carried out to try to entice future
humans, who might invent time travel technology, to come back and
demonstrate it to people of the present time.

13. THE
GRANDFATHER
PARADOX
 The grandfather paradox is a paradox of time travel in which
inconsistencies emerge through changing the past.
 A common objection to the idea of traveling back in time is put
forth in the grandfather paradox or the argument of auto-
infanticide.
If one were able to go back
in time, inconsistencies and
contradictions would ensue
if the time traveler were to
change anything; there is a
contradiction if the past
becomes different from the
way it is.

14. CONTINUED…
The paradox is commonly described with a person who travels to the
past and kills their own grandfather, prevents the existence of their
father or mother, and therefore their own existence.
Philosophers question whether these paradoxes make time travel
impossible.
Some philosophers answer the paradoxes by arguing that it might be
the case that backward time travel could be possible but that it would
be impossible to actually change the past in any way, an idea similar to
the proposed Novikov self-consistency principle in physics.

15. POSSIBLE
OUTCOME
Your time machine would break down, or your gun would jam
when you tried to kill your grandfather, or maybe you'd have a
sudden stroke and be paralyzed.
Whatever it was, the
universe would
appear to resist the
creation of paradoxes,
because the timelines
where it doesn't, you
cease to exist.

16. THEORETICAL
SOLUTION
 There is no approved solution to this paradox, but there are theories
where this isn’t a paradox anymore. One such theory is the theory of
Multiverse. It says there are many parallel universes, universes which are
identical to ours. So when you buckle up in a time machine and start your
journey, you end up in a parallel universe, at the wanted time.
 Travelling back in time to kill your grandfather alters the flow of time,
which creates a parallel timeline/universe. Hence, two alternate realities
are created in which your grandfather dies in one of them, and they do not
die in the other.

17. CONCLUSION
Wile concluding…. I will say that time travel to future is
more probable than to the past despite all these confusing
paradoxes . But we can’t ensure that time travel is
impossible at the same time surely possible.
THANK YOU.