relativity theory explained

1. Relativity
Theory
By:-
Albert
Einstein

2. About
Albert
Einstein

3. He was Born on :-
14 March 1879
At :-
Ulm, Kingdom of
Württemberg ,
German Empire
And died on:-
18 April
1955 (aged 76)
At :-
Princeton, New
Jersey, United States

4. He resided at:-
Germany, Italy,
Switzerland, Austria,
Belgium and United
States during his lifetime
Citizenship:-
Kingdom of
Württemberg (1879-1896)
Stateless (1896–1901)
Switzerland (1901–1955)
Austrian of the Austro-
Hungarian Empire (1911–
1912)
German Empire (1914–
1918)
Weimar Republic (1919–
1933)
United States (1940–1955)

5. Spouse:-
Mileva Marić (1903–
1919)
Elsa
Löwenthal (1919–
1936)
Children:-
Lieserl (1902–1903)
Hans Albert (1904–
1973)
Eduard Tete (1910–
1965)

6. Special
Relativity

7. Einstein's theory of Special Relativity is
based on two postulates:
Relativity Principle: The laws of nature
are the same in all inertial reference
frames
The speed of light in a vacuum is the
same in all inertial frames

8. • When we move with high speeds clocks
run slow, and meter sticks are length
contracted. In both cases the amount of
the time dilation or length contraction is
specified by the boost factor Gamma.
The boost factor for an object moving
with velocity v is given by the formula
• Gamma ( 𝛾) =
1
1−
𝑣2
𝑐2

9. The concept of clocks working slower and
length of objects becoming shorter
are termed as time dilation and length
contraction respectively

10. • An object is longest in its own rest
frame, while clocks at rest tick most
rapidly, i.e. show the shortest
elapsed time interval between two
events. As seen in a frame in which
they are moving , objects are
contracted and clocks tick more
slowly. In their own rest frame, all
lengths and clocks seem normal no
matter how fast another observer
sees them to move.

11. • In normal Galilean velocity addition formula,
vtotal = v1 + v2 but here the formula to add
velocities of objects will be:-
relativistic velocity addition formula which
is:-
𝑣 𝑡𝑜𝑡𝑎𝑙 =
(𝑣1 + 𝑣2)
(1 +
𝑣1 𝑣2
𝑐2 )
So if we use regular Galilean formula
then we will always get absurd results

12. • The prime example of a situation governed by
special relativity is a region far, far away in the
depths of space, far away from all stars and planets
(and their gravitational influence). Imagine that, in
this dark void, there are freely moving space
stations, drifting along without any acceleration or
rotation. On each of these stations sits an observer,
with his own clocks and his own measuring rods,
measuring times and distances. In addition, each
such observer has a fully equipped physics lab on
board, where he or she can perform a variety of
experiments to explore the laws of physics. This is
the kind of observer Einstein talks about, an
observer in a free, non accelerated frame of
reference. Such frames of reference (and such
observers) are commonly called inertial frames of
reference

13. If you think about space stations drifting along in
empty space, some statements that are surely
relative spring to mind right away: statements
about velocities. Imagine that, from the point of
view of observer A sitting on the upper deck of his
or own space station, the station of observer B
passes by at considerable speed:
The principle of relativity

14. • But from the point of view of observer B, his
own station is at rest. For him, it is observer
A's station that is moving:

15. • So who is moving and who is at rest? The
answer depends on which observer you
ask. Whether or not a space station
moves - and with what speed - is an
example of an observer-dependent,
relative statement.

16. Relativity of space and time
• Einstein's theory, simultaneity is a relative
concept. Imagine that there are two events
which an observer in space station A judges to
be simultaneous - say, the explosion of a
firecracker at one point in space and an alarm
clock going off a few miles away. For an
observer in space station B, which is moving
relative to A, this statement will not
necessarily be true: In general, such an
observer will come to the conclusion that one
of the events happened earlier than the other.

17. • Similarly, temporal duration depends on the
observer. This relativistic effect is called time
dilation. Summarized briefly: Moving clocks are
slower than stationary ones. A bit more precisely:
An observer on station A measures time using his
on-board clock. Station B, passing A at high speed,
has an exact copy of A's clock on board. Yet, from
the point of view of A, the clock in station B runs
more slowly than his own. A down-to-earth version
of this effect can be tested with the help
of elementary particles such as those particles
accelerated inside the "proton synchrotron" of the
European research centre CERN.

18. Space-time
• In special relativity, as was mentioned briefly, simultaneity is
relative, and so are time and space. Observers moving
relative to one another come to different conclusions about
which events happen simultaneously ("at the same time").
They agree only about what events there are, not about
where or when these events take place. Space-time, the
totality of all events, is absolute. But there are different ways
to slice that collection of events into snapshots of
simultaneity. When viewed in succession, these snapshots
show how, with time, changes take place in space. Different
observers, looking at different successions of snapshots,
come to different conclusions about which events are
simultaneous. Space-time is absolute, space and time are
not.

19. E=mc²
• The relativistic increase of mass happens in a
way that makes it impossible to accelerate an
object to light speed: The faster the object
already is, the more difficult any further
acceleration becomes. The closer the object's
speed is to light speed, the greater the
increase in inertial mass; to reach light speed
exactly would require an infinitely strong force
acting on the body. This enforces special
relativity's speed limit: No material object can
be accelerated to light speed.

20. • The increase in inertial mass is part of a more
general phenomenon, the
relativistic equivalence of mass and energy: If
one adds energy to a body, one automatically
increases its mass; if one takes energy away
from it, one decreases its mass. In the case of
acceleration, the object in question gains
kinetic energy ("movement energy"), and this
increase in energy automatically means an
increase in mass.

21. On the other hand, even an object at rest
turns out to have a certain amount of
energy. Energy and (inertial) mass are
inextricably linked by Einstein's famous
formula. Every body of mass m will
necessarily have a total energy
E=mc²

22. Conclusion
• Special relativity is more than just another
branch of physics. It is a framework into which
other physical laws can be embedded: All
physical laws in which space and time play a
role naturally depend on the properties of
space and time, and those are governed by
special relativity. Indeed, relativistic
generalizations have been found for almost all
laws of physics that predate special relativity.

23. General
Relativity

24. According to this theory Massive
objects cause a distortion in space
time.
Which is given by the equation:-
𝐺𝜇𝑣 + ∆𝑔 𝜇𝑣 =
8𝜋𝐺
𝑐4
𝑇𝜇𝑣

25. • With the general theory of relativity, in which
Einstein managed to reconcile relativity and
gravitation, he had to discard the traditional physics
worldview, which saw space as merely a stage on
which the events of the world unfold. Instead,
space-time is a dynamic entity, which is distorted by
any matter that is contained in it, and which in turn
tells that matter how to move and evolve. This
interaction between spacetime and matter is
described by Einstein's geometric, relativistic theory
of gravity.

26. • The consequences of that theory are
spectacular. For instance, general relativity
predicts that even light is deflected by gravity -
a prediction that has been confirmed by
numerous astronomical observations

27. Einstein's geometric gravity
In Einstein's theory of
general relativity, gravity is a
distortion of space-time.
Particles follow the straightest
possible paths in that space-time. But because
space-time is now distorted, even on those
straightest paths, particles accelerate as if they
were under the influence of what Newton
called the gravitational force.

28. Major application of General
relativity
• Newtonian physics predict an elliptical orbit
of a planet, with the sun in one of the focal
points..

29. • For the same situation, Einstein's theory predicts a
slightly different orbit: not an ellipse, but a kind of
rosette. As Mercury orbits around the sun, the two
points of each orbit closest to the sun and furthest
away from it (in astronomical lingo: perihelion and
aphelion) should ever-so-slightly shift from one orbit
to the next. The following figure shows an
exaggerated version of this movement:

30. • In the solar system, where there's more than one
planet orbiting the sun, the situation is a bit more
complicated. There, the mutual gravitational pull of
the planets on each other leads to a slight shift of
perihelion and aphelion points, even without
Einstein's results. However for Mercury, where the
relativistic effect should be strongest, the shift that
we observe is slightly larger than expected. Even
when the influence of all the other planets taken
into account, a slight extra contribution is left over.
A simple calculation in general relativity predicts
exactly that tiny additional shift.

31. The light side of gravity
• For the propagation of light, Einstein's theory makes
a clear prediction: Light is deflected by gravity. Just
as test particles move on the straightest-possible
lines in curved space-time (i.e. on space-time
geodesics), so does light.
• The most basic example: Light rays passing a
massive body are bent towards that mass. This
effect increases for light rays that pass the body at
smaller and smaller distances from it

32. • The first measurement of this relativistic effect was
made by British astronomers in 1919. They used the
fact that light deflection changes astronomical
observations. The "location of a star in the night
sky" is simply short-hand for "the direction from
which that star's light reaches us". Starlight that
passes close to the sun before reaching us gets
deflected, as sketched in the figure above (but by a
much smaller amount than is shown there). This
starlight will thus reach us from a slightly different
direction than when the sun is in some different
region of the sky. Accordingly, the star's position in
the night sky is shifted slightly.

33. Conclusion
• Einstein's theory of gravity
led physicists to a variety of
new models and
phenomena.

34. Black
holes

35. Formation and properties
• When massive stars explode in a supernova,
the collapsing central
• region will generically
• have so much mass that
• even neutron matter
• cannot halt the collapse.
• The collapse continues,
• and when this happens, a black hole is born

36. The black hole itself isn't a solid object, but
rather a region of space
with very special
Properties : Matter or light
can enter that region from
the outside,but nothing
that has entered can ever return. The border
separating this region from the rest of the world
is called the event horizon or, more simply,
the horizon of the black hole.

37. As the name implies,
an outside observer
will receive no light
from a black hole.
However, if you could
come close enough,
you could notice how
its presence deflects
the light of far-away
objects behind it.

38. The light of the stars and galaxies close to
the center of the image is deflected by the
black hole's gravitational influence. The
most obvious effect is that the light from
one of the objects is distorted to form a
ring around the black hole. This
phenomenon, called an "Einstein ring",
only occurs when the object and the black
hole are precisely aligned with the
observer.

39. Conclusion
• Relativistic physics is necessary to
fully understand the most energetic
phenomena in the universe -
from supernova explosions of stars
to the driving force that makes
some active galactic nuclei the
brightest objects in the universe.