How to Destroy the Universe (24 page)

The modern search for extraterrestrial intelligence (SETI) began 40 years ago, when two US physicists, Giuseppe Cocconi and Philip Morrison, published an article in the science journal
Nature
outlining how
microwaves could be used to communicate between the stars. At about the same time, a young US radio astronomer called Frank Drake independently reached the same conclusions. In 1960, he applied his ideas, pointing the 28m (90 ft) Green Bank radio telescope, in West Virginia, at two Sun-like stars to look for any microwaves that could be construed as a signal from ET.

While Drake's so-called Project Ozma found nothing, he did succeed in getting the attention of the rest of the astronomical community. In 1961, he organized the world's first SETI conference, at which scientists from around the world gathered to assess the chances of there really being intelligent life elsewhere in the Universe. In the early 1970s, NASA's Ames Research Center, in Mountain View, California, commissioned an external team of scientists to perform a feasibility study of SETI search methods. Their report, dubbed Project Cyclops, was optimistic about the chances of making contact with extraterrestrial life. Much of the SETI work done today is based on its findings.

By the end of the 1970s, Ames and the NASA Jet Propulsion Laboratory, in Pasadena, California, had established active SETI research programs. A number of universities had also set up their own projects. In 1988, NASA officials finally approved the plans made by their scientific researchers and granted
funds for observational work. Four years later the observations began, but shortly after that the US Congress canceled the project in a round of budget cuts that also saw the Superconducting Super Collider (SSC)—a giant particle accelerator, that would have been the most powerful in the world—coming under the ax. While the SSC was due to cost a hefty $5 billion, SETI took up just 0.1 percent of NASA's total budget, just 5 cents per American tax payer per year. The late space visionary Arthur C. Clarke cited the move as firm evidence that there was no intelligent life in Washington DC. But rather than rolling over and dying, SETI has been kept alive by a number of independent organizations. The SETI League is pulling together radio astronomers the world over to monitor the entire sky for signals from ET, while the SETI Institute is using some of the world's biggest radio telescopes to scrutinize specially targeted Sun-like stars.

SETI astronomers are looking for radio signals that fall in the range of frequencies between 1,000 and 3,000 megahertz (MHz, or million oscillations per second), referred to collectively as microwaves. They are the same sorts of waves that bounce around inside your microwave oven. While stars emit lots of visible light and other sorts of radiation, the galaxy is relatively quiet at microwave frequencies, making it a
sensible frequency for ET to transmit at. Quiet, that is, with one exception. Microwaves at a frequency 1,420 MHz are emitted in copious amounts by clouds of hydrogen in space. Researchers believe that this frequency will serve as a cosmic bookmark, and are searching the nearby, quieter microwave frequencies.

What form will the first contact with an extraterrestrial civilization take? Current surveys are just looking for signals that span a very narrow range of frequencies that are too narrow to have been produced by any natural phenomena. Astronomers know that any signal they detect that is narrower than about 300 Hz must be artificial in origin, because nature simply can't generate frequencies that precisely.

SETI researchers are confident that they're not searching in vain, and that there is intelligent life out there somewhere. There are roughly 400 billion stars in our galaxy. Recent astronomical observations have found planets around a large number of these, boosting scientists' suspicions that planet formation is a common process throughout the Universe. What are the odds of life forming on these planets? And if life is there, what about intelligence? When Frank Drake was planning the first SETI conference, he set about gauging how likely it is that there are ETIs in our galaxy. The result
was the Drake equation, a mathematical formula that uses quantities from cosmology, biology, technology and sociology to predict the number of extraterrestrial civilizations living in the Milky Way. Drake calculated that there could be millions of intelligent civilizations in our galaxy. Others have taken a more skeptical view. The Italian–US physicist Enrico Fermi famously asked the question, in 1950, “Where are they?” His argument was that given the age of the Universe, if there are intelligent civilizations living within it then they should have arrived at our Solar System by now. The fact that we don't see them, argued Fermi, is evidence that they don't exist. The late US astronomer Carl Sagan countered by pointing out that, “Absence of evidence is not evidence of absence.”

After Congress withdrew funding for NASA's SETI research, Frank Drake set up the SETI Institute, a privately funded organization, to continue the search, based in Mountain View, California. The principal activity of the SETI Institute at this time was Project Phoenix—a targeted search of 1,000 Sun-like stars, all within 200 light years of Earth. The project worked by dividing the microwave band into two billion 1 Hz channels and searching each one in turn for an unusually strong signal. Observations began in 1995, using the 70 m (230 ft) Parkes radio telescope in New South
Wales, then transferred to the giant 300 m (1,000 ft) Arecibo radio dish in Puerto Rico. In 1998, the UK's Lovell telescope at Jodrell Bank, the third-largest steerable radio telescope in the world, joined the project. Lovell's role was to determine whether potential “hits” detected by Arecibo were manmade or extraterrestrial. Project Phoenix ended in 2004 after failing to find any interesting signals in our part of the galaxy.

The more powerful a telescope is, the smaller the area of the sky that it can monitor. Project Phoenix used the most powerful radio telescopes in the world and so could only monitor very small portions of sky. The institute is now working on a new project, the Allen Telescope Array (ATA), after Microsoft co-founder Paul Allen, who stumped up $25 million to get the project off the ground. It is an interlinked network of 350 6 m (20 ft) radio dishes—located at Hat Creek Observatory, 450 km (300 miles) north-east of San Francisco, California. These dishes will combine to give the power of a single radio telescope 100 m (330 ft) across that's also fully steerable, allowing it to sweep large portions of the sky. By contrast, much of the observational work for Project Phoenix was carried out at Arecibo, which is a fixed-dish telescope. The ATA will be able to listen for alien signals coming from five times further away than Project Phoenix was able to detect, a range of nearly 1,000 light years.

The Allen Array works on a principle called interferometry, where the signals gathered by two or more radio telescopes positioned a distance “D” apart can be combined by a computer to form an image as detailed as one you might expect from a single telescope dish of diameter D. The ATA is already up and running with 42 dishes operational and gathering data.

Not all efforts to hunt down ET require vast professional-grade telescopes and millions of dollars of funding. Lower-power telescopes naturally have a wider field of view, enabling them to scan huge swathes of sky, albeit at lower sensitivity than the narrow-field, high-power searches conducted by the SETI Institute. And this is the tack adopted by the SETI League.

The League comprises 1,500 amateur and professional radio astronomers from 62 countries. Each participating member has a radio telescope in their back garden and a PC to analyze the results of their observations. Although modest by professional standards, a typical SETI League amateur set-up uses a dish between 3–5 m (10–16 ft) across. SETI League headquarters coordinates the project, designating each observer their own patch of sky to monitor. The program aims to monitor the whole sky. Although this would require around a million Arecibo-scale
telescopes, scientists hope to achieve all-sky coverage with just 5,000 low-power amateur instruments. This has the advantage over a targeted search of being able to spot life signs from planets that we may not be aware of, orbiting distant stars.

The closest thing to alien contact that astronomers have seen so far was spotted over three decades ago. Back in 1977, a SETI researcher at Ohio State Radio Observatory wrote “Wow” next to a huge radio-emission peak on a data print-out. Known from there-on as the “Wow!” signal, it was never seen again and so remains unverified. It was eventually written off as radio interference. Even earlier, back in 1967, two British researchers who weren't even looking for aliens thought for a brief time that they'd found them. Jocelyn Bell and Anthony Hewish found pulses of radio emission from space that were so regular, flicking on and off every second or so, that they thought the signal had to be produced by some form of intelligence. The truth was a little more prosaic, though still a significant discovery. Instead of aliens, Bell and Hewish had in fact discovered the first pulsar, a rapidly rotating neutron star (see
How to survive falling into a black hole
) which beams its radiation out into space rather like a lighthouse.

There is a set of protocols that must be adhered to if and when alien contact is made. First, the team making the claim must verify that ETI is the most plausible explanation for the source of their signal. Next the findings are submitted for peer review, where other astronomers are given the team's data and asked to verify or refute the claim. If confirmed, the Central Bureau for Astronomical Telegrams of the International Astronomical Union (who will pass the news to astronomers worldwide) and the Secretary General of the United Nations are both notified. The press is briefed shortly after. In the long term, the signal will be constantly monitored and the transmission frequency protected by international law. But will we reply?

The truth is that we already have replied. Television and radio signals have been spreading out into space for the last 60 years. Any alien civilizations within 60 light years of Earth and with sensitive enough detection equipment pointed in our direction may already be aware of our presence. But not all alien communication is accidental. One signal was sent from the Arecibo dish in 1974 toward a globular star cluster called M13. The signal contained information about our Solar System and life on Earth. However, M13 is 25,000 light years away, so we can't expect a reply for at least 50,000 years.

Whether or not astronomers would reply to a genuine SETI detection is a matter for debate. Many scientists—including Professor Stephen Hawking—have voiced their concern about announcing our presence in this way, arguing that we cannot be sure all life in the Universe will be peaceful. Indeed, if Hawking and colleagues are right, extending the hand of friendship to ET could instead be inviting war of the worlds.

• Endless energy

• Spinning black holes

• Hawking radiation

• The free lunch universe

• Quantum ratchet

History is replete with examples of optimistic inventors trying to get something for nothing—to build a device that can conjure energy from thin air. Scientists insist that such perpetual motion machines are impossible as they go against the fundamental tenets of physics. But one scientist thinks there may be a way around this problem. When it comes to generating energy, there may be such a thing as a free lunch after all.

From ever-turning water wheels in the works of mind-bending artist M.C. Escher to modern claims for devices that can extract never-ending energy from the behavior of electric currents in magnetic fields, perpetual motion machines have been rolling off
inventors' drawing boards since almost the year dot. True perpetual motion machines, which can output more energy than is put into them, are impossible. They violate a fundamental principle of physics known as the conservation of energy. This essentially says that energy can be neither created nor destroyed, merely changed from one form into another. For example, when you apply the brakes in your car, the car's kinetic energy is not destroyed. Instead, it is turned into heat and sound, which is then shed into the air rushing over the car's brake discs as it moves forward.

Conservation of energy is a keystone in every aspect of physics and has been tested by experiment perhaps more than any other physical law. So how is it possible to create energy from nothing? The secret lies in what you define “nothing” to be. Most of us would say empty space is nothing. But it turns out that empty space is in fact anything but empty.

One source of free energy that's done the rounds in the scientific literature is black holes. In 1963, mathematician Roy Kerr solved the equations of general relativity describing the space and time surrounding a rotating black hole. A static black hole would consist of a spherical event horizon surrounding a gravitational singularity—a point where the force of gravity and the
curvature of space both become infinite. However, Kerr was able to show that the space around a spinning black hole is significantly different (see
How to survive falling into a black hole
). In particular, he found that as well as an event horizon—from which there is no return—a rotating black hole is also surrounded by an ergosphere. This is a flattened spheroidal area (shaped like a basketball that's been squashed in a vice) within which space gets swept around with the black hole as it spins.

This effect is known as “frame dragging,” and can be imagined as rather like sticking a spoon in a jar of treacle and twisting it—the treacle near the spoon gets dragged around with it. Frame dragging was first derived from Einstein's equations in 1918, when Austrian physicists Hans Thirring and Josef Lense showed that all spinning bodies exert this effect on the space surrounding them. Just outside a spinning black hole, however, the effect is extremely strong. In 1969, British mathematician Roger Penrose worked out that it was possible to extract energy from the ergosphere of a spinning black hole. He devised a scheme whereby an object entering the ergosphere could get spun up by the frame dragging effect and leave with more energy than it came in with.