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Good evening, colleagues, I'm João Victor and I came to teach you a little
about the Universe. First, what do you find most interesting about the Universe and
everything in it? (wait for answer). For me, the immensity of the Universe and, perhaps,
the possibility of time travel is one of the most fascinating things. But... before talking
about that aspect, it's good to talk about how time travel would be possible

Basically, through 3 components of physics, besides the math, of course.

First, the black holes, so immense, but at the same time, so mysterious. This
one has already been proven, and in 2019 the first photo of a real one was taken,
more than 50 MILLION light years from us (that's a lot) (if anyone asks about the
light year, answer that "despite from looking like a measure of time, it's distance,
and it refers to the distance that light can travel in a vacuum, during a year, is
roughly 9.5 trillion kilometers)

Another thing is the theory of a white hole. If you have the black, why not have the
white?

Finally, the best part, the wormhole, like a shortcut in space-time. What is this
space-time thing? Calm down, I'll explain in a little while.

First, let me show you some of the fonts I used to build this project.
First, the books by the great physicist and author Stephen Hawking, The Universe in a
Nutshell, Brief Answers to Big Questions and a Brief History of Time, as well as
another, to explain the Universe, a book I will use more towards the end of the
presentation. .

However, in case you didn't know, several scientists are specialized in the studies of
the universe and its modifications, but two of which I will explain better, since their
contribution to science was infinitely greater than that of the others.

Albert Einstein was an important 20th century German physicist and

mathematician. He is known, for his genius, as one of the greatest scientists in all of history.
His great scientific creation was the General Theory of Relativity, a landmark in the
world of Modern Physics and Quantum Mechanics. With his Theory of Relativity he
changed humanity's thinking about time and space. This was presented by him in
1905, being re-presented with more information in 1915. But what was this Theory of
Relativity in fact?
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Contextualizing, before her, scientists thought that, for example, time and space
were two different things. Currently, this can be said to be wrong, since the two form
a kind of mesh, where all objects in the universe are on top, suffering the action of
gravity.

Also, from it, it is known that the speed of light is more or less 300 thousand meters
per second. That would be about 8 rounds of earth per second. Can you imagine
how much that would be? And that's why when the Sun explodes in a supernova, for
us, it will happen 8 minutes later (light takes 8 minutes from the sun to here).

Stephen Hawking was born in the city of Oxford in England. despite wanting to
study mathematics, he entered the physics course in 1959, against his father's
wishes. During his graduation period, Hawking discovered that he had a disease
called Amyotrophic Lateral Sclerosis (ALS). The consequences of this disease are
mainly muscle atrophy. When doctors diagnosed Hawking, they gave him a
maximum term of 2 years to live, however, his condition slowly progressed until his
death date on March 14, 2018, aged 76. Your fascinating theory is about black holes,
which I'll talk about in a moment.

Now that the presentation is done, can we start talking about black holes?

BLACK HOLES

The idea of a body so massive that even light could not escape was briefly
proposed by English astronomical pioneer and clergyman John Michell in a letter
published in November 1784. Michell's simplistic calculations assumed that such a
body could have the same density as the Sun. and concluded that such a body would
form when the diameter of a star exceeds that of the Sun by a factor of 500 and the
surface escape velocity exceeds the usual speed of light.
Michell correctly observed that these supermassive bodies, but not
radiation, can be detected by their gravitational effects on nearby visible bodies.[19]
[12][20] Scholars at the time were initially excited by the proposal that giant but
invisible stars might be hidden in plain sight, but that enthusiasm waned when the
wave nature of light became apparent in the early 19th century.
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But it was from Einstein, with his theories, that the theory that there were
black holes was finally revealed. They were researched for more than a century,
until it was finally proven, in 2019, the existence of one of them, photographed (the
black hole that “holds” the galaxy M87, more than 50 million light years from us)

The defining feature of a black hole is the emergence of an event horizon — a

boundary in space-time through which matter and light can only pass inwards
towards the mass of the black hole. Nothing, not even light, can escape from within
the event horizon. The event horizon is referred to as such because if an event
occurs within the boundaries, information from that event cannot reach an outside
observer, making it impossible to determine whether that event has occurred.

As predicted by general relativity, the presence of a mass warps space-time in such

a way that the paths taken by the particles lean towards the mass. At the event
horizon of a black hole, this deformation becomes so strong that there are no paths
away from the black hole.

To a distant observer, clocks near a black hole appear to tick more slowly than clocks
further away from the black hole. Due to this effect, known as gravitational time
dilation, an object falling into a black hole appears to slow down as it approaches the
event horizon, taking an infinite time to reach it. At the same time, all processes in
that object slow down, from the point of view of a fixed external observer, causing any
light emitted by the object to appear redder and darker, an effect known as gravitational
redshift. Finally, the falling object disappears until it can no longer be seen. Typically,
this process happens very quickly, with an object disappearing from view in less than
a second.

Now starting the theoretical part, let's talk about white holes. It has already been
explained that black holes, whatever goes in, can never come out, due to the massive
gravitational pull of the object. However, white holes are the opposite, nothing can
enter, only exit. In other words, according to the logic of many scientists, the black
and white holes would be a kind of tunnel, the black is the entrance and the white is
the exit. But tunnel for what? And where?

According to experiments carried out, a supermassive white hole would, in theory,

be the cause of the Big Bang, but the test failed.
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Moving on to the coolest part, Wormholes.

In physics, a wormhole or wormhole is a topological feature

hypothetical space-time continuum. A wormhole has at least two "mouths" connected
to a single "throat" or "tube". If the wormhole is passable, matter can "travel" from one
mouth to another by passing through the throat. Although there is no direct evidence
for the existence of wormholes, a space-time continuum containing such entities is
often considered valid by general relativity.

The term wormhole was created by the theoretical physicist

American John Archibald Wheeler in 1957. However, the idea of wormholes had
already been proposed in 1921 by the German mathematician Hermann Weyl in
connection with his analysis of mass in terms of the energy of the electromagnetic
field.

The name " wormhole" comes from an analogy used to explain the
phenomenon. In the same way that a worm that wanders through the skin of an
apple might take a shortcut to the opposite side of the skin of the fruit, making its way
through the core, instead of moving across the surface there, a traveler passing
through a wormhole would take a shortcut to the opposite side of the universe through
a topologically unusual tunnel.

Intra-universe wormholes connect one location in one universe to another location

in the same universe (at the same present or non-present time). A wormhole should
be able to connect distant locations in the universe by creating a shortcut through
space-time, allowing it to travel between them faster than light would travel through
normal space (see image above). Inter-universe wormholes connect one universe to
another. This gives rise to speculation that such wormholes could be used to travel
from one parallel universe to another. A wormhole that connects (generally closed)
universes is often referred to as a Schwarzschild wormhole. Another application of a
wormhole could be time travel. In this case, it's a shortcut from one point in spacetime
to another. In string theory, the wormhole has been seen as a connection between
two D branes, where the mouths are connected to the branes and are connected by a
flux tube.

Theoretically, if someone were to find a wormhole and travel through it, scientists
aren't sure how it would affect the individual. Some believe that a wormhole would
not remain stable long enough to allow crossing. And there are theories that suggest
that even if he
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remains stable, tidal forces in the vicinity of the hole can produce accelerations so
great that they would crush any traveler by compressing it transversely and
stretching it in the longitudinal direction.

Lorentzian wormholes, known as Schwarzschild wormholes or Einstein-

Rosen bridges are bridges between areas of space that can be modeled as vacuum
solutions to Einstein 's field equations by combining the models of a black hole and a
hole . white. This solution was discovered by Albert Einstein and his colleague Nathan
Rosen, who published the result in 1935. However, in 1962 John A. Wheeler and
Robert W.
Fuller published a paper demonstrating that this type of wormhole is unstable, and
that it will instantly collapse as soon as it forms, preventing even light from getting
through.

Before the stability problems of Schwarzschild wormholes became apparent, it was

proposed that quasars were white holes, constituting the end of wormholes of this
type.

Although Schwarzschild wormholes are not traversable, their existence inspired

Kip Thorne to imagine traversable wormholes created by keeping the “throat” of a
Schwarzschild wormhole open with exotic matter (matter that has negative mass/
energy), present in the great movie Interstellar.

The famous wormholes might work, but they don't explain how to prevent the
entropy of the Universe in the future from going through the wormhole into the Universe
of the past, as the entropy of the Universe increases continuously over time and there
will surely be more entropy in the future. Only mind travel would be possible, as there
would be no violation of the principle of conservation of energy. If we admit that it is
possible to send material objects to the past, we will have to admit a mass loss in our
future and a mass gain in our future.
past, or in the other alternative past. We would have to theorize a phenomenon that
accepts this paradox. According to Kip Thorne, this approach to time travel, mainly to
the past, has a very strong theoretical basis, but as mentioned before, it runs into the
problem of entropy, whose quantity increases with time, and is different for moments
in the past and future. . Eliminating the entropy problem is not feasible for the
ontological approach to the question of travel to the past, since the evolution of the
Universe indicates, according to Stephen Hawking, if the black hole theory is correct
and we understand the Universe as a black hole, that entropy growing contributes to
the dilation of the runaway horizon and the increasing expansion of the Cosmos, as
the event horizon is proportional to the amount of entropy and stores it.
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