Wednesday, October 6, 2021

Finding the begining

 The inflationary theory says that the universe came out of nowhere 15 billion years ago, as a particle 1 billion times smaller than a proton.  And it also suggests that the cosmos could once again become a lonely, icy space!

    The universe is amazing.  As far as the lenses of the most powerful telescope reach – the Hubble, which operates in orbit 300 kilometers from Earth – the news does not stop appearing.  Countless galaxies and their billions of stars (the Milky Way alone has 100 billion stars).  Mysterious black holes whose gravitational force devours even light.  Celestial bodies located at colossal distances, surpassed only by light, on its journey at 300,000 kilometers per second, after 11 billion years of existence.  Clouds of gases, asteroids floating aimlessly. 

 The visible universe is huge, but the equations of physicists and cosmologists leave no doubt: what we see is just a sample of the cosmos, about 5% of its mass.  The vastness of the heavens is fundamentally filled by the so-called dark matter, a kind of invisible fluid that spreads through space, and by dark energy, as yet only attested by astrophysicists' mathematics, based on certain phenomena in intergalactic space.

 Faced with such an eloquent scenario, however, it is impossible to silence the old question.  Where did all this come from?  In what ancestral womb all things were generated?  If you thought about answering “from the Big Bang”, then it's time to update your knowledge.

 The theory that the universe began in a big explosion (big bang, in English) was formulated in the beginning of the 20th century and has cooled the millenary discussion about whether the cosmos had a beginning or whether it has always existed.  Thanks to the discovery that the galaxies are moving away from each other, made by the American Edwin Hubble in 1922, it was not difficult to run the film in reverse and deduce that at some point in the past they were together, concentrated in a point of extreme density and very high temperature, whose explosion, until today, propels the fragments towards infinity.  But this model, accepted by almost 100% of scientists, is admittedly restricted and imperfect.  “The Big Bang is just about expanding from an initially dense and hot state,” says physicist Alan Guth, from the Massachusetts Institute of Technology, MIT, in the United States.  "The theory doesn't say what exploded, why it exploded, and what happened before that explosion."

 The Big Bang is actually reasoning about the result of the explosion.  The model assumes that all the matter in the universe was already there, just very compressed and in a shape different from its current state.  But how and where did this primordial substance come from?  It was in this gap that Guth himself found ground for a theory that intends to clarify the origin of what exploded in the bang.

 Where did the universe come from?  Alan Guth's answer is quick: from scratch, from scratch.  The first particles would have arisen from a simple vacuum fluctuation, a process of alteration of an electric field unknown to classical physics, but which quantum mechanics, born in the last century, ended up revealing to scholars of subatomic intimacy.  According to this conjecture – known as the inflationary universe theory – the primordial particles emerged from the void and expanded at an astonishing speed in billionths of a second, thus forming the agglomeration that would then be fragmented in the great explosion.  The theory neither contradicts nor replaces the traditional Big Bang explanation.  Complete it.  In practice, it provides the beginning from which supporters of the bang model assume and can continue, one of the reasons for its wide acceptance among physicists and cosmologists.

 from emptiness to spacetime

 “Guth's theory solves, at a single stroke, the mechanism of creation and the energy balance in the universe”, says astrophysicist Francisco Jablonski, from the National Institute for Special Research, Inpe, in São José dos Campos, SP.  "It makes room for scientific and philosophical reflections."  Among the hypotheses about the past and future of the cosmos under consideration in scientific circles, this is the one that best explains the data collected by telescopes and space probes in recent decades.

 When he claims that the universe was born out of nothing, Guth doesn't mean that matter took shape from something that didn't exist.  For a quantum physicist, emptiness is always something.  It is a situation where there is no space or matter, only high frequency energy.  By the laws of relativity and quantum mechanics, this energy can be converted into matter under uncertain and uncontrollable conditions, such as the sudden variation of an electric field or vacuum fluctuation.  This is exactly what would have happened in the circumstance that preceded the appearance of the universe, some 15 billion years ago.  In a sea of ​​energy full of virtual particles, which preceded space and time, the first particles probably materialized through quantum tunneling, a process in which the collapse of the energy wave causes the formation of particles, of matter.

 In theory, anything could emerge from a vacuum fluctuation.  Calculations and experiments in particle accelerators suggest, however, that only very small subatomic units can be generated in this way and for an infinitesimal lifetime, around 10-21 seconds (a decimal point followed by 20 zeros and then 1 ).  The situation is different when the matter generated is of a special type of vacuum fluctuation endowed with negative gravity, a force predicted in most theories of modern physics that, unlike normal gravitation, expels rather than attracts the particles present in its field.  In this case, it would be enough to form a part of only one billionth the size of a proton (one of the nuclear particles of the atom), for the expansion of matter to start due to the internal gravitational repulsion.

 In the genesis of the universe, this would have happened in the period between 10-37 seconds and 10-34 seconds, just enough time for the initial piece to reach the size of a marble.  From then on, the Big Bang would have happened and the expansion would have continued at another pace.

 This is the detectable zero point with the current resources of deduction and scientific experimentation, which does not mean, according to Guth, the final word on the alpha of creation or even the discarding of the hypothesis that the universe had no beginning, sustained, among others , by Albert Einstein.  The idea of ​​inflation and the concept of negative gravity have an irrevocable impact on all other cosmological hypotheses.

 the matter factory

 The Big Bang theory is limited to justify the estimated mass of the universe and its thermal equilibrium.  It would be necessary to fine-tune the equations that demonstrate the theory, to reconcile it with what is observed today in the cosmos.”  This disagreement is overcome when the inflationary model is taken into account, which, according to Reis, explains the creation of matter without contradicting the laws of physics.

 Guth's theory states that, in the early universe, repulsive gravity material expanded without losing density, generating during inflation a colossal mass of quarks, tiny particles with an electrical charge less than that of an electron.  At first glance, it seems that the phenomenon collides with the principle of energy conservation, which presupposes the balance of total energy in all transformations in the physical world, but that is not what happened.  In the inflationary process, the positive energy of matter was balanced by the negative energy of the gravitational field, so that the total energy was always zero.  When the negative gravity material began to decay, halting the rate of inflation, then the primordial soup (gas at very high temperature) was formed, considered to be the initial condition of the Big Bang.

 At that time, 10-6 seconds into the cosmos's conception, there were still no atoms and molecules, just a boiling plasma made up of electrons, protons, positrons, neutrinos, and a whole range of polarized subatomic particles.  Ordinary matter would only appear about 300,000 years later, when the universe had cooled down enough to allow free electrons to combine with atomic nuclei and form the hydrogen and helium that burn inside stars.  It was then that dark matter circles would have helped to compress huge volumes of the two gases, promoting the formation of stars.  But the stars and galaxies we see today are not the same as those back then, says cosmologist Volker Bromm of the Harvard-Smithsonian Center for Astrophysics in Cam-bridge.  The first stars had enormous mass, glowed intensely, but exploded before completing 3 million years, which turned out to be fundamental for the continuation of creation.

 When they exploded, these stars propelled the condensed gas around them into space, in addition to scattering atoms heavier than those of hydrogen and helium, enabling the birth of the second generation of stars.  The first galaxies ended up colliding and merging into large clusters of stars.

 Martin Rees believes that without this interruption in the chain of creation, the cosmos would not have consolidated in its current form, nor would there be the necessary conditions for life.  If all the initial gas had remained inside the first stars, the raw material of the celestial bodies would have been consumed and today the universe would exhibit a set of red stars, gathered in dwarf galaxies.  Agglomerations like the Milky Way, rich in gas, would be exceptions to the rule.

 In the bowels of nature, Rees says, this difference in favor of life happened with surprising precision.  For example: in the combustion process of stars, when hydrogen and helium fuse, only 0.007 of the helium's mass is transformed into energy – and it is exactly this number, according to Rees, that guarantees the chemistry of life.  If it were a little smaller - 0.006 - the two protons and two neutrons that make up the nucleus of the helium atom would not join and the universe would have only hydrogen.  If the number were higher (0.008), the fusion would be so fast that no hydrogen atom would have survived an event like the Big Bang.  Therefore, the existence of solar systems and living beings would be made impossible by the absence of one or another element.

 permanent creation

 The inflationary model raised lessons that go beyond the traditional concept of the cosmos and reinforce unconventional theories developed from the 1930s onwards. One of them is that of parallel universes or pocket universes, which would operate in other dimensions of space and time, being, therefore, invisible to our eyes and to current electronic sensors.  “Such parallel universes would be the result of topological defects due to the diversity of electric field variations and inflation levels in the first moments of the cosmos”, says Reis.  Their number would be enormous, but it becomes even greater when considering the possibility of the eternal inflation of matter.  In this case, according to Guth, the repulsive gravity material would continue to grow without limit and without end, producing more matter, in an infinite succession of universes.

 The history of the cosmos in this scenario would have numerous versions, as physicist Richard Feynman proposes, and may not have started with our own universe.  Some even admit that the Big Bang may have been caused by the collision of two universes.

 The accelerated expansion casts a bleak picture for the distant future, when galaxies are lost in a dusty and frigid space, with a temperature much lower than the current minus 273 degrees of space.  Of the billions of galaxies observable today, only two will remain visible from Earth: our Milky Way and Andromeda, the only one moving towards us.

 a theory of everything

 There are dozens of theories designed to explain the origin and dynamics of the cosmos, and with each discovery of astronomical observatories, many gain new versions.  Guth's own inflationary model derives from earlier deductions, such as those of Russian-American physicist Andrei Linde of Stanford University, who in the 1980s conceived of the existence of different quantum fields in the universe before the Big Bang.  The second half of the 20th century, however, was marked by the effort of physicists and cosmologists to arrive at a unified theory that would bring together valid elements from different models and clarify the enigmas of the universe.

 One of the best known models is that of Albert Einstein.  The physicist who elaborated the Theory of Relativity thought that time should be infinite in both directions and, therefore, defended the hypothesis that the universe has always existed.  According to the mathematician and doctor in cosmology Stephen Hawking, from the University of Cambridge, in

 England, Einstein did so to avoid embarrassing questions about the creation of the universe outside the realm of science, but the calculations of Hawking and his colleague Roger Penrose, based on Einstein's own concept of general relativity (which presupposes the curvature of spacetime ), led to another conclusion.  “Time would have to start at the Big Bang,” says Hawking.  "And an end when stars or galaxies collapse under their own gravity to form black holes."

 Einstein's model, not yet discarded, leads to an oscillating universe scenario, which would alternate periods of expansion, from bangs, and contraction to the singularity of black holes - points at which matter returns to the condition of concentration, energy and infinite temperature, like before the start of everything.  It is reminiscent of the assertion of the Stoic philosophers in ancient Greece that the world is destined to be infinitely destroyed and reconstructed.  And also the notion of cycles of destruction and construction of the mystical doctrines of the East, such as Taoism and Hinduism.

 The point is that the current assessment of the radiations from the stars, which signal the accelerated departure of the galaxies, suggests a flat universe, in the process of eternal expansion, which strengthens other cosmological hypotheses.

 When the so-called superstring theory was developed in the 1980s, it was thought that a Theory of Everything had finally been achieved.  The model proposes the existence of 11 dimensions (strings), which would involve the existence of similar universes and others totally different from ours, where there could be even more than one time dimension or no stars or galaxies.  The theory doesn't rule out events like the Big Bang, it just doesn't consider them as episodes of a unique story for the cosmos.

 Today, the hope of obtaining a single theory is represented, for Hawking, in Theory M (for “matrix”), which connects five versions of string theory.  “What has convinced a lot of people to take models with extra dimensions seriously is the web of unexpected relationships between them,” says Hawking.  "This shows that all models are different aspects of the same basic theory."

 on the edge of science

 Cosmology is not a static science and has constantly surpassed ideas that seemed unshakable in the past, a fact that is justified, in part, by the very object of its study – the immensity of the universe – and the limitation to test its theories in the laboratory.  It is in the mathematics of scientists that the models assert themselves, waiting for future confirmation by new astronomical discoveries or experimental proofs in particle accelerators.  At the moment, the limit of cosmology is the vacuum fluctuation, cited in this article.  To understand what existed before this stage, recalls Francisco Jablonski, it would be necessary to advance further in the knowledge of quantum gravity.  “From that point on, you can only speculate outside the realm of science”, says Hugo Reis.

 However, theoretical and mathematical physicists have been trying, in the last four decades, to break this barrier with audacious hypotheses that bring physics and cosmology closer to philosophical and even religious inferences (the concept of matter formation by vacuum fluctuation, incidentally, recalls the Buddhists' emptiness, the transcendental womb where everything is generated and where everything returns).  This is the case of the American physicist John Archibald Wheeler, a colleague of Einstein and Niels Bohr and mentor of several exponents of modern physics, who coined the expression “black hole”.  At 90, Wheeler strives to demonstrate that the universe is real, in part, because we observe it.  Maybe the cosmos doesn't exist when we don't look at it.  Just like this magazine would only exist because you are looking at it.

 His arguments are based on the laws (and laboratory experiments) of quantum physics, which demonstrate, for example, that the behavior and trajectory of an electron are always influenced by the observer.  In an experiment, the electron can behave like a particle or like a wave and follow this or that path in its journey from one point to another: the decisive factor in any of the possibilities will always be the eye of the experimenter.  In quantum mechanics the universe seems to emerge as an extremely interactive place, at least at its fundamental levels.

 Wheeler supposes a cosmos where not only the future is indeterminate, but the past as well.  When we immerse ourselves in time in search of our origin – in the Big Bang or primordial fluctuation – our current observations would select one of the many possible quantum histories for the universe.  Wheeler is not alone.  Renowned physicists, such as Andrei Linde, even consider that a Theory of Everything will never be successfully established without taking into account the interaction between reality and the observer and even the presence of a consciousness as a factor in the construction of the universe.

 The adventure of deciphering the cosmos is far from over and it may never end.  The consolation is that it is one of the most fascinating in science – research delights even when the answers are far away.

 inflationary universe

 How quantum gravity saved us from absolute zero.


 Quantum Gravity: Energy Containing Virtual Particles

 10-37 seconds

 After vacuum fluctuation, sudden change in electric field, photons turn into tiny particles.  Gravitational repulsion initiates the inflation process, expanding the area and creating matter

 10-6 seconds

 The first protons and neutrons appear.  The particles collide with each other.  The gas heats up, the particle soup explodes in the Big Bang

 300 000 years

 Cooling allows the appearance of the first atoms and the first stars are born

 1 billion years

 The first galaxies with few stars collided with each other, giving rise to the clusters we know today

 10-34 seconds

 End of accelerated inflation.  The universe is the size of a marble

 15 billion years

 Today, galaxies continue to expand

 150 billion years

 In an even cooler cosmos than today, the galaxies will be so far apart that from Earth we will only see the Milky Way and Andromeda.


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