João Pedro de Magalhães

Cosmology

"I don't think the human race will survive the next thousand years unless we spread into space." — Stephen Hawking


The Insignificance of the Human Race

What initially attracted me to cosmology was how insignificant our lives are. In this vast universe there are billions and billions of stars and planets and we are but a miniscule fraction of it all. Imagine how many mysteries lie within each star system waiting to be uncovered. Our knowledge concerning the universe is still in its infancy and I believe that our most glorious future is the discovery of this vast knowledge. In an infinite universe, there are infinite possibilities. The idea of god might not be as unlikely as I usually claim, even if unlike anything we can predict. Though we might be insignificant now, perhaps one day we'll understand the universe and even dominate it. Perhaps one day we shall become gods of all there is and there will ever be.

The Mysterious Cosmos and Reflections on God

"The universe is not only queerer than we suppose, but queerer than we can suppose." — J.B.S. Haldane

Why does the universe exists? Was it created by someone or something? Is there a purpose to the universe? These are old questions without answers. According to the latest discoveries in physics, we might be very lucky to be alive. For example, the mass of the electron is perfect for life. There may even be many universes in a multiverse, many zones in our universe that do not allow the existence of life. Why are there quarks, electrons, etc.? Why do these elementary particles have the properties they have? Why should there be an answer to these questions? To put it another way, is there a hidden logic to the parameters ruling our universe?

Will we ever stop to find even smaller components of the universe? Some researchers have proposed that particles smaller than electrons and quarks exist and they are vibrating one-dimensional filaments. This forms the basis of the superstring theory, though it is so complex that no-one has yet been able to expose all its equations and so I'm a bit skeptic to accept it as the theory of everything. Still, I believe there may be a simple underlying framework explaining our universe.

The anthropic principle states that we see the universe as it is because otherwise we wouldn't be here to see it, we wouldn't exist. Some claim there are many universes in the Cosmos and because their sub-atomic particles are slightly different than ours they do not support life. The Cosmos is everything, infinite, while the universe is the space-time that formed after the big bang -- assuming that only one big bang formed what we call universe -- and of which we are a part of. Perhaps there is a god. Perhaps some species was capable of manipulating space and time and then decided to create this universe.

It is safe to assume that the universe began with the big bang; a huge black hole so dense that it exploded giving rise to matter and even dimensions began expanding. But what existed before the big bang? Has the big bang been repeating itself for a longer time than can be expressed in words? Was there a beginning? What if some species was able to manipulate space and time in such a way that it was present in a previous version of this universe and was able to survive the big bang. Perhaps there is a god or many gods. Perhaps some species did survive and create this universe for its entertainment.

Artist's view of star formation in the early universe. By Adolf Schaller. Source: NASA.

A DNA polymerase is an enzyme that adds nucleotides to match a template chain, thus complementing the DNA chain. Certain enzymes can insert about 1'000 nucleotides per second, which is unimaginable to us. We are unable to understand this processing power. If a god exists that is larger than, say, a light-year, its relation towards us is the same as our relation towards an enzyme. We see enzymes as simple, as part of us, and as incredible fast in processing their programs; a god would sees us like that. Since information cannot travel faster than light, with our current knowledge (but see below), it would take years for a god to think but that would be the price to pay for complexity. To its perception, assuming he could perceive us, we would have an extremely short lifespan. That is, if I can even begin to understand how a god thinks.

Actually, the existence of gods is not consistent with all observations. The two most likely origins of a god are a previous universe that disappeared in the big bang and another universe. What exists at the boundaries of the universe, however, is beyond comprehension. Some claim that dimensions would not exist and mathematics, namely, the now popular superstrings theory, shows that indeed the four dimensions in our universe might not be the only possibility; it has been argued that other dimensions are folded and are thus imperceptible to us. Of course that the human brain is not capable of understanding this, in the same way we can't understand the infinity of time and space because we lack a value for it. Either way, how would a god survive with no time and space? Perhaps gods create their own space-time. Can an entity survive a big bang? With our current knowledge it can't but with such primitive understanding of the universe it's hard to discard any hypotheses. Some claim that our universe is like a bubble connected to other bubbles by wormholes, perhaps even a bubble rising in another bubble.

In Men In Black, the movie ends by showing an alien playing with our universe. Perhaps that's not that so fictitious. I'm an atheist but I do admit the possibility exists. Of course that I discard any possibility of gods such as the ones proposed by most religions as these are scientifically impossible. Omnipresence, a full understanding of everything, is impossible according to Heisenberg's indeterminacy principle. I'm sure there is no god to help people who are good and that the gods created by human religions are merely inventions to help people cope with our chaotic human existence destined to death and eternal oblivion. If there are gods, they are not interested in us except, perhaps, for curiosity or study; rewarding the good is not likely to be the objective of a god the same way it is not our objective to help the ants that work the most towards the common good of the colony. Overall, there aren't any proofs of the existence of gods, which means they probably don't exist. And if we reach the point where we can detect their presence they're most likely to be our foes than friends.

The universe's topology is another area of much controversy. Some say the universe is not a sphere or oval but instead has a rather different shape. Some scientists argue that the universe is like a disk while others claim it's a Doughnut Space: instead of having one single trajectory between 2 points, there would be several possibilities for light and radiation to travel between 2 points; the universe would no longer be an Euclidean or hyperbolic universe. The universe might not even be infinite and if one was to travel in one direction, instead of eventually reaching the end of the universe, one would be back to the starting point. The best evidence for this multiply connected universe is the fact that the universe looks the same in terms of radiation and composition whatever the direction we turn to.

I like to think that our universe is like a support, a tissue for our existence in a much more vast and unknown Cosmos. But if space-time does not exist outside our universe, then what is replaced when our universe enlarges? We are like fishes in water with no way to detect its existence, blind to the cosmological medium in which we live.

Time Travel

Laplace's determinism offered for some time the promise of time voyages. Well, we wouldn't indeed travel in time and change the present but we would be able to virtually go to the past. The idea was that if we could determine all variables of all particles, we could develop an Universal Computer, "a device able to compute anything computable," that could be used to predict the past and even the future. Life is information. By this process we would be able to, say, bring back to life people long gone. Fortunately, or unfortunately, according to Heisenberg's indeterminacy principle, this is impossible. If we're looking at atomic particles, a computer's memory occupies more space than the space that is being monitored; a Universal Computer would have to be composed of sub-atomic particles or it would be larger than the universe its trying to simulate; but if even the sub-atomic particles's position was to be calculated, the problem would persist. It might be claimed that this would lead to an eternal miniaturization, because determining the attributes of smaller and smaller particles is imperative for the model to be accurate, and ultimately the impossibility of constructing such a device.

Presently, the idea of time travel is not completely discarded. Time and space are not uniform in the universe. The space-time is folded and curved in certain areas of the universe. Therefore it might be possible to break the space-time tissue to access other points in the universe. We don't know what happens when we break the space-time where we live. The energy needed for such task -- Planck's energy -- is not within our reach, not yet at least. Besides, in black holes the conditions exist for such space-time radical deformations. In a black hole, the amount of energy is such that it has been proposed that a bridge, called an Einstein-Rosen bridge, exists linking two universes. To avoid death by the gravitational force of a black hole concentrating on a single point, a rotating black hole can provide a way, a wormhole to pass through space-time. The destination is unknown but probably a white hole in another universe or another part of our universe.

Einstein's equations also allow for time travel. Kurt Gödel showed that if the universe was full with a fluid or rotating gas, anyone moving in that universe could be back at the starting point at an earlier time. The idea of developing warp drives based on this principle of the space-time deformation is therefore possible, despite the huge amounts of energy needed for such an endeavor. Unfortunately, the technical aspects of such constructions completely overwhelm us. We can propose other ways of time travel: Casimir plaques that act as warp gates connecting 2 places, an infinite cosmic cylinder, etc., but not only don't we know if these constructions are stable but the engineering capacity for such constructions is well beyond what is now possible. Besides, although theoretically wormholes might exist they might not allow anyone to actually survive inside one.

If one day we can travel to the past, the consequences are unimaginable. We don't even have to think about someone killing our ancestors, we can just think of chaos theory and parallel lives. What would a caveman say about a nuclear device? For now such concepts are beyond comprehension and remain in the realm of science fiction.

Going Faster than Light

We know very little about the universe and many theories can be questioned. Information cannot travel faster than light but, for example, the speed of phase of a wave can exceed the speed of light despite not being able to be used to send messages. In a recent experiment, scientists claimed that a pulse of light passing through a chamber with a specially prepared cesium gas is pushed to 300 times its normal velocity; so fast, in fact, that the main part of the pulse of light exits the chamber before it actually gets into it. Faster-than-light neutrinos have also been proposed, though remain to be proven. Quantum teleportation, which basically consists of transferring a particle's properties to another particle anywhere in the universe instantaneously, might one day be used to send messages. Interestingly, the existence of particles that travel faster than light and go back in time have been theorized. They are called tachyons but so far they have not been proven to exist. Overall, it might just be possible to transmit information faster than light.

In the context of information, it is interesting to note that quantum theory claims that information cannot disappear from universe. But black holes may make information disappear, creating a interesting paradox. Perhaps, as John Preskill proposes, the information doesn't really vanish. It is somehow displayed on the surface of the black hole, as on a cosmic movie screen.

The End of the Universe

The end of the universe is another controversial topic. Our universe can be a closed, open, or a flat universe. A closed universe is the one that collapses back into a new big bang, called a big crunch, thus starting a new cycle. An open universe is the scenario where the universe will be in constant expansion, also called a big chill because energy would become scarce. Finally, in a flat universe expansion comes to a stop after an infinite time. The threshold mass in the universe that will determine what the future of the universe will be is about five atoms per cubic meter. Probably, the amount of dark matter is going to decide the fate of our universe. Whatever the outcome, we'll probably need warp drives to move to other universes if we don't want to die either by fire or ice, assuming humankind survives long enough which is admittedly unlikely.

On trying to determine the fate of the universe, scientists made an awkward observation: the universe is expanding faster with time. Because gravity is the only known force acting at such distances, the universe's rate of expansion should be decreasing. These results, if confirmed, suggest that there is some unknown force(s) we don't know about. One possibility concerns dark matter. It is estimated that over 90% of the universe is composed of an unknown type of matter whose properties can be completely different from what we know and perhaps this mysterious matter generates the antigravity effect we witness.

One of the most original and bizarre ideas was proposed by Lee Smolin and concerns viewing black holes as the offspring of the universe we inhabit. If other universes are to originate at each black hole then the black hole's event horizon prevents us from knowing anything about these universes. Now, perhaps the characteristics -- i.e., force strengths, particle masses, etc. -- of these new universes will be somewhat related to our universe but with some random factor at work too. We could then be in the presence of a genetic process by which black holes reproduce. It's an interesting but unlikely, speculative idea.

Masters of the Universe

"The earth is the cradle of the mind, but one cannot stay in the cradle forever" — Konstantin Tsiolkovky

The conquest and colonization of the universe is our future for several reasons:

  1. It is the normal evolutionary step and the expected result of human curiosity and ambition.
  2. It might be our only way to avoid a totalitarian government, nuclear wars or other major cataclysms (e.g., an asteroid or comet hitting us).
  3. Our resources on earth are limited.
  4. The sun will eventually explode and we will have to seek a new home.

Whatever the reasons are, we will have to seek new planets and stars as we blossom into a galactic civilization. The first step will be to use all our resources on earth to become a Type I civilization. In order to do this, many social and political problems will have to be solved, so we can finally have a united humankind based on equality, knowledge and peace. Afterwards, we need to start evolving an efficient use of our natural resources. Soon afterwards, if fusion power and nanotechnology turn real, terraforming other planets will be possible and we will dominate the solar system.

Artwork of space colonization. Source: NASA.

The greatest energy source in our solar system is the sun itself. Freeman Dyson proposed that a ring can be built around stars to recover their energy to the fullest. This ring or small constructions would then begin to be joined up until a megascale engineering construction called a Dyson Shell enveloped the star. This way no energy would escape the sun. Some have suggested that dark matter might be Dyson Shells, though such a construction would likely emit radiation because of energy leaks that could presumably be detected. Anyway, this ingenious idea could, if feasible, gives us the energy we would need to advance into a Type II civilization.

Traveling among planets in our solar system is already possible to some degree even if still extremely expensive, but traveling to other star systems poses new problems. The first step will probably be using unmanned probes to scan the surrounding systems for resources and life. We might use something called a Von Neumman probe. This is an autonomous device capable of landing on a distant planet, making decisions, analyzing the environment, and even reproducing.

With the advent of nanotechnology, nanodevices may be used in Von Neumman probes and much more. As I explain elsewhere, there are practically no limits to nanomachines. The key concept is to send them to other star systems where they can use energy sources to build new spaceships. It will become an exponential process of propagation of human existence. Outposts will be built on strategic planets or asteroids in each surrounding star system, and even on any celestial body not orbiting a star. They will then inform us about the other planets in the system and the possibility of life. If we find it appropriate we can order certain planets to be terraformed. Artificial Intelligences (AIs) will most likely be much evolved by this time, which means we'll have an entity more intelligent than us in the spaceship. This computer would have to make many decisions on its own because it would take years to communicate with earth. It would also need to take into account the possibility of finding other life forms. From earth we would later send humans to colonize the other star systems.

There are many technical problems to be solved, but many ideas as well. To build a space station we need a better process to escape earth's gravity. Launching pads are a good solution to put simple materials into orbit, and serious efforts are being made to build these. Leik Myrabo proposed the use of a lightcraft: a device propelled by directing a laser beam onto the rear of the craft. Once we escape gravity, ion drives will probably be the next generation. They will be useful in trips in the solar system and even abroad. Fusion reactor and even reactors that use nuclear bombs as impulses are other proposals, although not very likely, unless major technical breakthroughs are made in that field -- they might be used to escape gravity but not to travel between planets and stars. Other proposals include antimatter drives and warp drives; however, although these are physically possible, they are technically inaccessible in the near future. An anti-mater drive would be very powerful but, while theoretically possible, it remains science fiction. A warp drive would allow us to travel through wormholes, as discussed before, but we'll have to wait and see if it's a possible concept. An interesting idea is that hyperspace might already be crowed by alien civilizations and by building a warp gate we end up in some alien planet. Another likely development of our civilization at this point would be Jupiter Brains. These are huge, planet-sized intelligences that would allow us to analyze information in ways never predicted before.

Once we establish a galactic empire, we can become a Type 4 civilization. We, or what has then become of the human species, would become masters of everything. By then we would probably know if wormholes are possible and what happens at Planck's energy. The possibilities are immense. We would know why we exist, we would reach the Omega point and become god, if the position hasn't been taken already.


Sources and Links

Hawking, Stephen W.; "A Brief History of Time — From the Big Bang to Black Holes" (1988). Also check his official website.

Greene, Brian; "The Elegant Universe" (2000). A very good book concerning superstring theory.

Kaku, Michio; "Visions; How Science Will Revolutionize the 21st Century" (1998). Interesting book covering different topics. Also check his website.

Parker, Barry; "Einstein's Dream" (1986).

Russell, Bertrand; "ABC of Relativity" (1969).

Sagan, Carl; "Cosmos". Sagan's old classic.

Trefil, James; "Other Worlds" (1999). Basic information.

Anthropic principle

European Space Agency

NASA; also check their section on astrobiology and Imagine The Universe!.

Ned Wright's Cosmology Tutorial

Quantum Teleportation; short and interesting.

Space.com

The Planetary Society

Universe Today