Thanks for joining me!
Good company in a journey makes the way seem shorter. — Izaak Walton
E.T. Phone Home
The SETI Institute was created by astronomers such as the late Carl Sagan, and other notable individuals such as William Hewlett and David Packard of Hewlett-Packard fame, Nathan Myhrvold and Paul Allen of Microsoft, and several others. Using data from the sources such as Arecibo, Hubble, and Spitzer, SETI has spearheaded the search for life in the universe, and well as the search for extrasolar planets. In the late 1990’s, the SETI@home project was established to utilize the computing power of millions PCs distributed throughout the world as an ad hoc supercomputer of sorts to help sift through the mounds of data received from optical and radio telescopes and from data gathered by the Hubble and Spitzer Space Telescopes. The method used by SETI and others to search for extraterrestrial life makes the broad assumption that other life forms would use the electromagnetic spectrum for communications. We assume that the laws of physics are constant in the observable universe, so other intelligent civilizations would have also invented or stumbled across the idea of using the electromagnetic spectrum for communications.
One hole in this strategy is that E.T. may not be using a phone or a radio to call home. Although we pat ourselves on the back for all of our scientific inventions, it could be that there’s an entirely different medium of communications staring us right in the face. In fact, it may be doing just that. It could be that photons can be designed to carry information at the speed of light, and may employ some unknown type of encoding or modulation to carry messages. E.T. might even use dark energy to communicate, or perhaps employ neutrinos. We have enough trouble just detecting neutrinos, but to a more advanced civilization, perhaps these elusive little particles are as common as table salt.
Another possible flaw in this strategy is that there may in fact be life out there, but perhaps it is microbial in nature and is unable to answer. We’ve certainly discovered many examples of extremophiles here on Earth, so it could be that space is teaming with these forms of life. We just don’t know what to look for. Fermi suggested that given the size and age of the universe that it is unlikely we’re alone, but more likely, we’re just not looking in the right place or using the correct methods. Of course, there are other theories. Some feel that life is just a transitory stage and that we will ultimately dry up and blow away like doggy doo-doo. Still others feel that we’re being kept in a zoo, perhaps contained so we don’t screw up the rest of the universe.
Perhaps the biggest joke of all is using the human race as a yardstick for defining ‘intelligent life’. It’s pretty arrogant to use ourselves as the gold standard for intelligence. We’re a race that over centuries has butchered our brothers and sisters to possess their wealth, gain power, or force our views of religion on each other. A list of the genocide, wars or major conflicts throughout the relatively short time we’ve inhabited our planted could fill volumes. In the last two hundred years alone we’ve managed to strip the Earth of most of its natural resources, polluted our oceans, rivers, and streams, and partially destroyed the critical elements of our atmosphere that shield us from harmful radiation and help maintain a climate conducive to life. We’ve already left enough nuclear waste to keep our descendants on their guard for the next 25,000 years.
In our search for E.T., we often state that we’re looking for ‘other intelligent life in the universe’. This presupposes that we’re in the same category as extraterrestrials because after all, they couldn’t be more intelligent than we are, right?
Where in the heck is E.T.?
Much has been published about the search for “intelligent life”. We’ve been scanning the heavens for radio signals that might have been sent by another civilization or from another planet, although we haven’t found anything yet. We’ve also been broadcasting our own radio signals hoping that someone or something in the universe is also listening. We’ve actually been broadcasting our existence for some one hundred years now in the form of television and radio broadcasts. In January of 1903, Gugliemi Marconi transmitted a signal from Massachusetts to Great Britain, and in 1909, Marconi and Karl Braun were awarded the Nobel Prize in physics for their work in wireless radio transmissions. Radio and television broadcasts have been emanating from Earth on a regular basis for decades, and the signals that have been created here are now on their way to other parts of the universe. Since those signals are relatively simple, it should be easy for an advanced alien civilization to receive and decode them. So why have we never received a reply? Where is everyone?
One of the reasons we haven’t heard from anyone is that the universe is a big place; a very, very big place, and it takes a long time for a radio signal to be sent or received. Let me try to put it in perspective.
Throughout the universe, the laws of physics appear to be uniform. Gravity, dark energy, electromagnetism, and light appear to work the same as they do here on Earth. Einstein’s cosmic speed limit of 186,000 miles per second applies not only to light but to radio waves sent from Earth as well as radio waves sent from other places in the universe. While the speed of light is fast, it pales in comparison to the immense distances encountered in the universe.
The Earth orbits our Sun at a distance of some 93 million miles. Several other planets also orbit the Sun, and together they comprise our solar system. Our solar system is located in one of the arms of a spiral galaxy we call the Milky Way. The Milky Way galaxy is a group of over 400 billion planets and stars. It is over 120 thousand light years wide. The Milky Way is so large that our solar system has only made 16 round trips around the center of the galaxy since the universe was formed some 13.7 billion years ago.
The galaxy closest to us where we might find life is M31 in the constellation Andromeda, a galaxy with over one trillion stars. Close is a relative term, however, since Andromeda is some two million light years from Earth. The light we see from Andromeda has taken over two million years to get here, so we’re seeing it today as it was two million years ago. A radio signal from Andromeda would have to have been sent over two million years ago to allow us to receive it today. It will take our radio signals two million years to reach Andromeda. Since we’ve only been broadcasting for about 100 years, it will be a long time before anyone there might receive them.
Suppose we wanted to travel to Andromeda. Using our current propulsion technology, a space shuttle that left Earth would take about 75 billion years to reach Andromeda. If we were able to travel at the speed of light (which is impossible given Special Relativity), it would still take 2.5 million years to get there. And as galaxies go, Andromeda is our next door neighbor.
In spite of these obstacles, we should not stop looking. It could be that other civilizations are much more advanced and may have other communications technologies that are superior to ours. Some of those civilizations could have been around much longer than the human race, and may have been searching for other life forms millions of years before the human race appeared on the Earth.
Another possibility is that they don’t want to disclose their existence for a variety of reasons.
There’s another possibility, however. I’m convinced that if an advanced civilization ever looked at us, they’d consider us a barbaric and backward society and not worth the effort. These potential visitors would only have to review our history of wars, genocide, and violence to determine that there’s no intelligent life down here. They’d probably decide to let natural selection takes its course.
A neophyte’s view of cosmic inflation
In 2001, physicists Justin Khoury, Burt Ovrut, Paul Steinhardt, and Neil Turok published “Ekpyrotic universe: colliding branes and the origin of the hot big bang”. In that paper, the authors attempt to explain the origin of the universe, not as the result of the proverbial “big bang”, but rather as the collision of two membranes or “branes”, three-dimensional worlds that exist in a hidden dimension. The term ekpyrotic comes from the ancient Greeks who used the word to describe the creation of the “world in fire”. Steinhardt et al used the word to describe their theory of how they believe the universe was created .
The ekpyrotic universe is an alternative theory to the big bang theory of the creation and expansion of the universe. While the widely accepted “big bang” theory assumes a center or singularity, a starting point of high density and high temperature where the universe began, the ekpyrotic universe is believed to have been created as a result of quantum effects caused by the collision of two three dimensional worlds. (Steinhardt). The underlying concept of the ekpyrotic theory is rooted in quantum mechanics, the interaction between subatomic particles which caused photons to be released. The big bang is based largely on Newtonian physics that are not applicable to the ekpyrotic theory.
Not everyone has bought into the ekpyrotic theory, however. According to Brian Greene, the colliding branes would have to be parallel with each other with an accuracy of better than 10-60 on a scale of 1030 times greater than the distance between the branes (Kallosh and Linde).
The so-called big bang was not a bang at all; in fact, it was probably no more than a whimper. It is believed to have taken place in a single space, an area of infinite density and extreme heat. In this state, photons interacted in a reaction that caused the universe to be created. The time it took to create the universe was very small, referred to as the Planck time, 10-43 seconds. Pairs of photons collided to form particle pairs such as electrons and positrons, a process called pair production. According to this theory, the universe began to immediately expand and has continued its expansion over time. The current observable distance to the edge of the universe is approximately 46.5 billion light years (Harrison, 2000). As the universe continued to expand, the density of the universe decreased, along with the temperature. In accordance with Wien’s law, the decrease in temperature should lead to longer wavelengths or redshifts which is exactly what Edward Hubble observed in the late 1920’s, and his observations helped bolster the big bang theory. The theory of the creation and expansion of the universe based on the cosmic singularity has been widely accepted and still remains the prevailing theory among most scientists. Scientific studies and measurements seem to corroborate the big bang theory.
Hubble analyzed the redshift observed from remote galaxies and determined that there was a relationship between the amount of redshift and the distance to those galaxies. He concluded that the galaxies were moving away at a rate of approximately 73 kilometers per second per Megaparsec (Mpc), which is referred to as the Hubble Constant, H0.The reciprocal of this constant can be used to calculate the approximate age of the universe. The result, about 13 billion years, seems to agree with the age of the Earth and solar system as calculated using the isotropic composition of lead in the universe, a result of the decay of Uranium.
In the mid 1960’s, scientists discovered that the universe contained background radiation, referred to as the cosmic microwave background radiation, or CMBR. The wavelengths of the CMBR indicate distinct patterns of energy indicative of photons, which have been propagating over billions of years. The temperature of the CMBR also supports the big bang theory. The universe contains more helium than what could have been generated by stars, so scientists have concluded that the large amount of helium must have been produced as a result of very large thermonuclear reactions, so the universe must have been very hot. The temperature of the CMBR today reflects the calculated expected drop in temperature using Wien’s law, which corroborates not only the theory of the big bang, but also the approximate age of the universe. Certain temperature signatures in the CMBR are also consistent with the type of thermal variations that would be generated by quantum fluctuations of matter that existed in a small space. The fluctuations, which take place at the subatomic level, are more aptly described using quantum mechanics.
One of the problems with the big bang theory is that it doesn’t quite fit the outcome we observe today. It does not provide an explanation of why the universe is essentially flat, nor does it provide mechanisms for the creation of stars and galaxies. The big bang theory did not initially explain why the background radiation is isotropic, which tends to indicate that the universe did not begin with the cosmic singularity. In an attempt to resolve some of this discrepancy, scientists have modified the big bang theory to include a period of very rapid expansion where the universe expanded by a factor of a million trillion trillion times in less than a millionth of a trillionth of a trillionth of a second (Greene). This modification to the big bang theory provided an explanation of the uniformity of the CMBR.
While it is the best theory that scientists have created, some missing pieces cannot be explained away using the big bang model. Supporters of the big bang are constantly tweaking their theories in an attempt to reconcile some of these inconsistencies to fit the big bang model.
Burt Ovrut, Paul Steinhardt, and Neil Turok originally presented the ekpyrotic theory at a meeting of the Space Telescope Science Institute in 2001. The authors posited that the universe began not in a state of infinite temperature and density as described by the big bang theory, but in a cold, vacuous state. From this state, the hot universe we know of was born. Expansion continued in the way we understand. The major difference between the ekpyrotic universe and the universe generated by the big bang is in how the universe actually began. According to the ekpyrotic theory, the universe began as a collision between two adjacent branes. The result was the release of energy in the form of quarks, electrons, and photons. The collision happens everywhere at the same time, so there is no one point of cosmic singularity. The result is a homogeneous universe that has a uniform density and temperature. During the collision, ripples along the flat geometric surfaces generate fluctuations in the microwave background, which are believed to stimulate the formation of galaxies (Steinhardt).
The fundamental concepts of the ekpyrotic theory are rooted in M-theory, a theory that describes the movement or vibration of one-dimensional strings in a multidimensional space. The ekpyrotic theory is based on unproven ideas in String theory that include an 11-dimensional space, while the big bang inflationary model is based on the well-understood and accepted Quantum Field theory. Despite wide acceptance and support, String theory has not been proven. It has been suggested by the world’s leading most prominent physicist Edward Whitten that String theory may require a new mathematical language all its own to describe it.
In the ekpyrotic universe, we would expect to find that the CMBR is isotropic and uniform, the same regardless of position or location. We would also expect to find no gravitational wave effects in the CMBR, nor would we expect to find strong magnetic poles, as the lower temperature of the ekpyrotic universe would likely prevent them from being created. The existence of very massive magnetic monopoles is a necessary consequence of most unified theories of the strong, electromagnetic, and weak interactions (Longo). These massive monopoles which consist of magnetically charged particles would be present in a universe created by the big bang, but would be absent in a universe created at a lower temperature as massive particles would not be released.
While the big bang theory has undergone many years of scrutiny, the concept of the ekpyrotic universe is still relatively new. Although quantum field theory is well understood, the quantum effects that are thought to have generated the ekpyrotic universe have yet to be proven or recreated. Superstring theory is still just a theory, although it is beginning to gain traction. However, only a relatively few years ago we thought the atom was the basic building block of the universe. Both the big bang and ekpyrotic theories are likely to be debated for many years to come as scientists work to unravel the basic building blocks of the universe. While we don’t know which, if any of the theories are correct, they have given us not only a better understanding of our world, but the motivation to continually push the envelope in an attempt to understand the origin of the universe.
Greene, Brian. The Fabric of the Cosmos. New York: Random House, 2004.
Harrison, E.R. Cosmology. Cambridge: Cambridge Universtiy Press, 2000.
Kallosh, Renata and Andrei Linde. “Pyrotechnic Universe.” High Energy Physics (2001): 35.
Longo, Michael. “Massive magnetic monopoles: Indirect and direct limits on their number density and flux.” Physical Review D (1982).
Steinhardt, Paul. A Brief Introduction to the Ekpyrotic Unverse. n.d. 27 November 2010 http://www.princeton.edu/~steinh/npr/.