Will we ever travel to other stars?

Answer 1

HEAD: How to survive the end of the Universe



SUBHEAD: The cold, dark end is coming. We need an escape plan



By Michio Kaku



THE Universe is out of control. Not only is it expanding, but the expansion itself is accelerating. Most likely, such expansion can end only one way: in stillness and total darkness, with temperatures near absolute zero, and conditions utterly inhospitable to life.

That became evident in 1998 when astronomers at the Lawrence Berkeley National Laboratory and Australian National University were analysing extremely distant, and thus ancient, Type Ia supernova explosions to measure their rate of motion away from us. (Type Ia supernovas are roughly the same throughout the Universe, so they provide an ideal "standard candle" by which to measure the rate of expansion of the Universe.)

Physicists, scrambling to their blackboards, deduced that a "dark energy" of unknown origin must be acting as an antigravitational force, pushing galaxies apart. The more the Universe expands, the more dark energy there is to make it expand even faster, ultimately leading to a runaway cosmos. Albert Einstein introduced the idea of dark energy mathematically in 1917 as he further developed his theory of general relativity.

More evidence came in 2003 when data from the Wilkinson Microwave Anisotropy Probe, or WMAP, which analyses the cosmic radiation left over from the Big Bang, found that dark energy makes up a full 73 per cent of everything in the Universe. Dark matter makes up 23 per cent. The matter we are familiar with - the stuff of planets, stars, and gas clouds - makes up only about 4 per cent of the Universe.

As the increasing amount of dark energy pushes galaxies apart faster and faster, the Universe will become increasingly dark, cold and lonely. Temperatures will plunge as the remaining energy is spread across more space. The stars will exhaust their nuclear fuel, galaxies will cease to illuminate the heavens, and the Universe will be littered with dead dwarf stars, decrepit neutron stars, and black holes. The most advanced civilizations will be reduced to huddling around the last flickering embers of energy - the faint Hawking radiation emitted by black holes.

Insofar as intelligence involves the ability to process information, this, too, will fade. Machines, whether cells or hydroelectric dams, extract work from temperature and energy gradients. As cosmic temperatures approach the same ultralow point, those differentials will disappear, bringing all work, energy flow, and information - and the life that depends on them - to a frigid halt. So much for intelligence.



CROSSHEAD: Facing the challenges



A cold, dark Universe is billions, if not trillions, of years in the future. Between now and then, humans will face plenty of other calamities: wars and pestilences, ice ages, asteroid impacts, and the eventual consumption of Earth - in about 5 billion years - as our Sun expands into a red giant star.

To last until the very end of the Universe, an advanced civilisation will have to master interstellar travel, spreading far and wide throughout the galaxy and learning to cope with a slowing, cooling, darkening cosmos. Their greatest challenge will be figuring out how to be somewhere else when the Universe dies, essentially finding a way to undertake the ultimate journey of fleeing this Universe for another.

Such a plan may sound absurd. But there is nothing in physics that forbids such a venture. Einstein's theory of general relativity allows for the existence of wormholes, sometimes called Einstein-Rosen bridges, that connect parallel universes. Among theoretical and experimental physicists, parallel universes are not science fiction. The notion of the multiverse - that our Universe coexists with an infinite number of other universes - has gained ground among working scientists (read PM's story on "Parallel universes", October 2003).

The inflationary theory proposed by Alan Guth of the Massachusetts Institute of Technology (MIT), to explain how the Universe behaved in the first few trillionths of a second after the Big Bang, has been shown to be consistent with recent data derived from WMAP. Inflation theory postulates that the Universe expanded to its current size inconceivably fast at the very beginning of time, and it neatly explains several stubborn cosmological mysteries, including why the Universe is both so geometrically flat and so uniform in its distribution of matter and energy.

Andrei Linde of Stanford University has taken this idea a step further and proposed that the process of inflation may not have been a singular even; that "parent universes" may bud "baby universes" in a continuous, never-ending cycle. If Linde's theory is correct, cosmic inflations occur all the time, and new universes are forming even as you read these words.

Naturally, the proposal to eventually flee this Universe for another one raises practical questions. To begin with, where exactly would an advanced civilisation go?

As it happens, physicists are spending billions of dollars on experiments to probe the nature of parallel universes. Since 1997, scientists at the University of Colorado at Boulder have conducted experiments to search for parallel universes perhaps no more than a millimetre away from ours. The experiments searched for tiny deviations in Newton's inverse square law of gravity. The surface of a sphere in three dimensions is equal to 4? times the radius squared. Likewise, the surface of a sphere of higher dimensions is proportional to the radius cubed.

According to Newton's law, in such a sphere the measurable gravity should decrease as a factor of the distance cubed. So the Colorado physicists set about measuring the gravity within a small, defined space. If the gravitational force deviated significantly from Newton's equation (the distance squared) and was more closely proportional to the distance cubed, the research team theorised, that would suggest the presence of a hidden dimension.

Newton's inverse square law has been tested with exquisite precision by space probes, but it had never been tested at the millimetre level. So far, the results from these experiments have been negative, but other scientists are looking for even smaller deviations. A group at Purdue University has proposed testing Newton's inverse square law down to the atomic level using nanotechnology.

Physicists elsewhere are exploring other possibilities. In 2007, the Large Hadron Collider, the world's largest atom smasher, will be turned on outside Geneva, Switzerland. This huge machine, more than 8 km in diameter, is capable of blasting protons together with a colossal energy of 14 trillion electron volts; it will be able to probe distances 1/10 000 the size of a proton, perhaps creating a zoo of exotic particles not seen since the Big Bang.

One hope is that it will create exotic particles such as miniature black holes and sparticles, or supersymmetric particles, which would indicate the presence of parallel universes in higher dimensions.

In addition, the space-based gravity-wave detector LISA (Laser Interferometer Space Antenna) will be launched some time around 2012. It will consist of three satellites trailing Earth's orbit around the sun and communicating with one another via laser beams, thereby creating a triangle with sides more than 4,8 million km long.

LISA is designed to detect faint gravity waves from extremely far away - gravitational shock waves that were emitted less than a trillionth of a second after the instant of creation. The instrument is so sensitive that scientists hope it will be able to test many of the theories that seek to explain what happened before the Big Bang and probe for the existence of universes beyond our own.



Crosshead: Harnessing vast energies



To journey safely from this Universe to another - to investigate the various options and do some trial runs - an advanced civilisation will need to be able to harness energy on a scale that dwarfs anything imaginable by today's standards.

To grasp the challenge, consider a schema introduced in the 1960s by Russian astrophysicist Nikolai Kardashev that classified civilisations according to their energy consumption. According to his definition, a Type I civilisation is planetary: it is able to exploit all the energy falling on its planet from the sun (1016 watts). This civilisation could derive limitless hydrogen from the oceans, perhaps harness the power of volcanoes, and perhaps even control the weather. A Type II civilisation could control the energy output of the sun itself: 1026 watts, or 10 billion times the power of a Type I civilisation. Deriving energy from solar flares and antimatter, Type IIs would be effectively immune to ice ages, meteors, even supernovas.

A Type III civilisation would be 10 billion times more powerful still, capable of controlling and consuming the output of an entire galaxy (1036 watts). Type IIIs would derive energy by extracting it from billions of stars and black holes. A Type III civilisation would be able to manipulate the Planck energy (1019 billion electron volts), the energy at which space-time becomes foamy and unstable, frothing with tiny wormholes and bubble-size universes. The aliens in Independence Day would qualify as a Type III civilisation.

By contrast, ours would qualify as a Type 0 civilisation, deriving its energy from dead plants - oil and coal. But we could evolve rapidly. A civilisation such as ours, growing at a modest 1 to 2 per cent per year, could make the leap to a Type I civilisation in a century or so, to a Type II in a few thousand years, and to a Type III in a hundred thousand to a million years.

In that time frame, a Type III civilisation could colonise the entire galaxy, even if their rockets travelled at less than the speed of light. With the inevitable Big Freeze at least tens of billions of years away, a Type III civilisation would have plenty of time to develop and test an escape plan.

Why not start now? On the following pages are experiments and plans to guide a civilisation looking for a way out - a survival guide to the end of the cosmos.



MAIN HEAD: Seven steps to leaving the cosmos



HEAD: Find and test a theory of everything



Before an advanced civilisation leaps into the unknown, it will need to study the pathways that make it possible to break through to the other side. Toward that end, scientists will need to discover the laws of quantum gravity, which will help to calculate the stability of wormholes connecting our Universe to others.

At present, the leading - and, some believe, only - candidate for a theory of everything is string theory, or M-theory. This theory states that all subatomic particles are different vibrations or notes on a tiny string or membrane. These aren't ordinary strings, but rather strings that vibrate in higher-dimensional hyperspace. In principle, our Universe might be a huge membrane drifting in 11 dimensions, which may occasionally collide with a neighbouring membrane or universe. It is possible that our Universe and a neighbouring one hover only a millimetre or less from each other, like two parallel sheets of paper. To bridge even this tiny distance, however, we'll need machinery of vast power.



HEAD: Search for a naturally occurring wormhole



Next, in order to escape from this Universe into another one, we will need to find a suitable exit: some wormhole, dimensional gateway or cosmic tunnel that connects here to there.

There are many possibilities, some of which may occur naturally. The Big Bang, which released a tremendous amount of energy, may have left behind all manner of exotic entities of physics such as cosmic strings, false vacuums, or negative matter or energy. The original expansion of the Universe may have been so rapid and explosive that even tiny wormholes might have stretched and blown up to macroscopic size. The discovery of such entities would greatly aid any effort to leave a dying universe; if they exist, we would do well to find them.

Perhaps by the time the need arises, billions of years from now, an advanced civilisation will have stumbled upon one of these gateways. In the meantime, we should consider a more proactive strategy.



HEAD: Send a probe through a black hole



Black holes offer another possible avenue of escape. One advantage of black holes is that, as scientists now realise, they are plentiful in the Universe. The one at the centre of our galaxy has a mass more than 3 million times that of our Sun. Of course, there are numerous technical problems to be worked out. Most physicists believe that a trip through a black hole would be fatal.

Although Einstein's equations permit the possibility of passing through a black hole, the quantum effects may be insurmountable. However, our understanding of black hole physics is in its infancy, and this conjecture has never been tested.

A reasonable first experiment would be to send a test probe through a black hole. Of course, any such venture would be a one-way trip; every black hole is surrounded by an event horizon, a point of no return beyond which not even light (and perhaps information) can escape the immense gravitational pull. Knowledge could be gleaned from the probe up to the moment it finally crosses the event horizon and all contact is lost.

An intense, and most likely lethal, radiation field surrounds the event horizon. (Light rays gain tremendous energy as they fall into a black hole.) A probe could determine precisely how much radiation permeates this region - useful data for subsequent missions.

A probe might also settle some critical questions about the stability of black holes. In 1963, mathematician Roy Kerr showed that a rapidly spinning black hole will collapse not into a dot but rather a rotating ring that cannot break down because of centrifugal forces. A Kerr ring has the same topology as Alice's looking glass; the wormhole at its centre might connect our Universe to other points in the same universe or to an infinite number of parallel universes. These parallel universes may be stacked on top of one another like floors in an elevator skyscraper.

Scientists disagree over what happens if one enters a Kerr ring. For example, some say that sending a probe in might destabilise the black hole, reduce the event horizon to a singularity, and shut the wormhole altogether. This controversy gained fuel in July last year when Stephen Hawking, reversing a famous wager he'd made seven years ago, suggested that information entering a black hole may not be irretrievably lost after all. Throwing a probe into a black hole would disturb the Hawking radiation it emits, he argues, and might permit information to leak out. All the more reason to send in a probe and see what happens.



HEAD: Create a black hole in slow motion



Once the characteristics near the event horizon of a black hole are carefully ascertained by probes, the next step might be to create a black hole in slow motion to gain further experimental data on the characteristics of space-time.

In a 1939 paper, Einstein envisioned a swirling mass of stellar debris slowly collapsing under its own gravity. He concluded that such a mass alone could not contract on a large enough scale to form a black hole, but he had not considered the now-familiar concept that the object could implode. His work leaves open the possibility that if one could slowly inject sufficient additional matter and energy into the spinning system, one could kick-start an implosion and create a black hole.

Consider that a Type III civilisation would be capable of accumulating matter on a galactic scale. To form a black hole, one might gather a swirling collection of neutron stars, which are each about the size of Manhattan but possess more mass than our Sun. Gravity will gradually bring the stars closer together, at which point our advanced scientists might carefully add more neutron stars to the mix. Once the total matter exceeds about three solar masses, the combined gravity would force the stars to collapse into a spinning ring - a Kerr black hole.

Armed with a new-found ability to create and study wormholes under controlled circumstances, future scientists would greatly advance their knowledge of how wormholes form - and how best to traverse them.



HEAD: Create negative energy



If Kerr rings prove to be lethal or too unstable for use as cosmic portals, an advanced civilisation might instead contemplate opening up a new wormhole by using negative matter or negative energy. (In principle, negative matter or energy should weigh less than nothing and fall up rather than down. This is different stuff from antimatter, which contains positive energy and falls down.) In 1988, Kip Thorne and his colleagues at Caltech showed that with sufficient negative matter or negative energy, one could create a wormhole through which a traveller could freely pass back and forth between, say, his laboratory and a distant point in space or time.

Although no one has yet seen negative matter or negative energy in the wild, it has been detected in the laboratory, in the form of something called the Casimir effect. Consider two uncharged, parallel plates. Theoretically, the force between them should be zero. But if they are placed only a few atoms apart, then the space between them is not enough for some quantum fluctuations to occur.

As a result, the number of quantum fluctuations in the region around the plates is greater than in the space between. This differential creates a net force that pushes the two plates together. Hendrik Casimir predicted the effect in 1948; it has since been confirmed experimentally.

The amount of energy involved is minuscule. To employ the Casimir effect to practical ends, one would have to use advanced technology to place the parallel plates at a fantastically small distance apart - 10-33 cm, the Planck length (the smallest measurement of length with any meaning). Now suppose that these two parallel plates could be shaped into a single sphere, with the plates forming a sort of double lining, and pressed together to within this fractional distance. The resulting Casimir effect might generate enough negative energy to open a wormhole within the sphere.



HEAD: Make a baby universe



If both Kerr rings and negative-energy wormholes prove unreliable, Guth's inflation theory points the way to another, more difficult escape strategy: creating a baby universe.

As Guth points out, to create something resembling our Universe would require "1089 photons, 1 089 electrons, 1089 positrons, 1089 neutrinos, 1089 antineutrinos, 1079 protons, and 1079 neutrons." However, Guth notes, the positive energy of this matter is almost but not entirely balanced out by the negative energy of gravity. (If our Universe were closed, which it isn't, the two values would cancel each other out exactly.) In other words, the net total matter required to create a baby universe might be measured in grams.

But what grams! In principle, baby universes are born when a certain region of space-time becomes unstable and enters a state called the false vacuum. The false vacuum needed to create our Universe is extraordinarily small, on the order of 10-26 cm wide. If one created this false vacuum from 28 g of matter, its density would be a phenomenal 1080 grams per cubic centimetre. Acquiring a few grams of matter is easy; compressing it into the small volume necessary is not possible today.

The solution requires that a fantastic amount of energy, roughly equal to the Planck energy, be concentrated on a tiny region. Here are two approaches an advanced civilization might try.



HEAD: Build a laser implosion machine



The power of laser beams is essentially unlimited, constrained mainly by the stability of lasing material and the energy of the power source. Lasers that can produce a brief terawatt, or trillion-watt, burst are commonplace, and petawatt lasers capable of generating a quadrillion watts are possible. By contrast, a large nuclear power plant produces only a billion watts of continuous power. It is theoretically possible for an X-ray laser to focus the output of a nuclear bomb to create a pulse of unimaginable power.

At the Lawrence Livermore National Laboratory in the US, scientists have used a laser to fire a series of high-energy pulses radially on to a single pellet made of deuterium and tritium, the basic ingredients of a hydrogen bomb, thus creating the conditions for thermonuclear fusion.

An advanced civilisation could create a similar device on a much larger scale. By placing huge laser stations on asteroids and then firing millions of laser pulses onto a single point, future scientists could generate temperatures and pressures that swamp today's technology. Each laser could be powered by a nuclear bomb; however, such a device would be usable only once.

The aim of firing this massive bank of laser beams would be to either heat a chamber sufficiently high - about 1029 degrees Kelvin - to create a false vacuum inside or compress a pair of spherical plates to within the Planck distance of each other, creating negative energy via the Casimir effect. One way or the other, a wormhole connecting our Universe to another one should open within the chamber, allowing us to exit.



HEAD: Build a cosmic atom smasher



One of the most powerful energy-generating devices currently available to scientists is the Large Hadron Collider, which, when it becomes operational in 2007, will be able to generate 14 trillion electron volts. Even that is one-quadrillionth the energy necessary to create a false vacuum.

But a particle accelerator with the diameter of our solar system might do the trick. Gigantic coil magnets could be placed at strategic intervals on asteroids to bend and focus a particle beam in a circular path around the Sun. (Since the vacuum of empty space is better than any vacuum attainable on Earth, the beam of subatomic particles would not need light-years of tubing to contain it; it could be fired into empty space.) Fair warning: the magnetic field required by each coil to bend the beam would be so huge that the surge of power through it might melt the coil, making it usable only once. After the beam has passed, the melted coils would have to be discarded and replaced in time for the next pass.

Alternatively, it is worth noting that the Large Hadron Collider may be the last generation of giant particle accelerators to use radio-frequency energies to boost subatomic particles around a giant ring. Physicists are already attempting to build tabletop-size laser-driven accelerators that, in principle, could attain billions of electron volts.

So far, scientists have used powerful laser beams to attain an acceleration of 200 billion electron volts per metre, a new record. Progress is rapid, with the energy growing by a factor of 10 every five years. Although technical problems hamper the development of a true tabletop accelerator, an advanced civilisation has billions of years to perfect these and other devices.

In the interim, to reach the Planck energy with something like current laser technology would require an atom smasher 10 light-years long, reaching beyond the nearest star. Power stations would need to be placed along the path in order to pump laser energy into the beam and to focus it - a minor task for a Type III civilisation.



HEAD: Send in the nanobots



Assume now that the wormholes created in the previous steps prove unworkable. Perhaps they are unstable, or too small to pass through, or their radiation effects are too intense. What if future scientists find that only atom-size particles can safely pass through a wormhole? If that is the case, intelligent life may have but one remaining option: send a nanobot through the wormhole to regenerate human civilisation on the other side.

This process occurs all the time in Nature. An oak tree produces and scatters seeds that are compact, resilient, packed with all the genetic information necessary to re-create a tree, and loaded with sufficient nourishment to make colonisation possible. Using nanotechnology, an advanced civilisation might well be able to encode vast quantities of information into a tiny, self-replicating machine and send this machine through a dimensional gateway.

Atom-sized, it would be able to travel near the speed of light and land on a distant moon that is stable and full of valuable minerals. Once there, it would use the raw materials at hand to create a chemical factory capable of making millions of copies of itself. These new robots would then rocket off to other distant moons, establish new factories, and create still more copies. Soon, a sphere of trillions of robot probes would be expanding near the speed of light and colonising the entire galaxy.

Next, the robot probes would create huge biotechnology laboratories. They would inject their precious cargo of information - the preloaded DNA sequences of the civilisation's original inhabitants - into incubators and thereby clone the entire species. If future scientists manage to encode the personalities and memories of its inhabitants into these nanobots, the civilisation could be reincarnated.

Mathematically, this is the most efficient way for a Type III civilisation to colonise a galaxy, not to mention a new cosmos. If we ever encounter another intelligent life-form, chances are it won't be in a flying saucer like the starship Enterprise. More likely, we'll make contact with a robot probe they've left on a moon somewhere.

This was the basis of Arthur C. Clarke's 2001: A Space Odyssey, which may be the most scientifically accurate depiction of an encounter with an extraterrestrial intelligence. In the film version, this logic was originally articulated by scientists in the film's opening minutes, but director Stanley Kubrick cut the interviews from the final edit.

HEAD: Strange but true

Although seemingly fantastic, these scenarios are consistent with the known laws of physics and biology, and would be within the capabilities of a Type III civilisation. For a civilisation caught in the last days of an expanding Universe, these may be the only options for escape.

© Discover Magazine, December 2004, Volume 25 No 12. Adapted from the book Parallel Worlds: A Journey Through Creation, Higher Dimensions, and the Future of the Cosmos, published by Doubleday. Copyright © 2004 by Michio Kaku.

Answer 2

Hi. Not with our limited knowledge for a long time. I always keep an open mind because you never know.We would have to travel faster than the speed of light which is impossible.Maybe we will find another way like some form of magnetic propulsion,or as in Star Trek transferring our bodies through a transponder to instantly arrive at our destination.Now i know this is science fiction but some science fiction has actually come true.

Answer 3

Not until we get a faster than light engine or propulsion, or be in sleep mode for centuries at present speeds, mars round trip at present speeds two years to get there, a year wait until the orbits are right and two years back, also consider hydroponics (food ) , oxygen , fuel , water toilet requirements , medical, craft maintenance some sort of lander , transport when there, it will have to be a mighty big ship, which could not be built down here, that's why the space wheel is so important to build to put it together

Answer 4

I examine someplace that for the duration of 50 years the great floor of this planet would be coated with human beings, so evidently like we don't have the different techniques, different than for to vanish or to unfold contained in the universe. i think of you in no way comprehend as quickly as we gonna hit upon a suitable technologies. in certainty you in no way comprehend whats gonna take place contained in the subsequent 10 years. How approximately that: genetics will provide us version to opposed environments, jointly as AI, robotics and nanotech will supply us with suitable techniques and components and right here we bypass - the photograph voltaic equipment is ours. this is what we can assume good now. If relativity and quantum theories gave us nuclear technologies, then who's conscious of, in line with risk destiny breakthrough in physics will clarify the thank you to construct a starship. playstation I examine in some technology fiction novel, that an attempt to create a blackhole has forced human beings to realize the celebs, simply by fact the test went incorrect and, you comprehend, earth replaced into starting to be an unusual place to outlive...

Answer 5

With the current physical body and the technology its not possible.
If mankind survives the time laps a satellite travels to another star, it might be able to provide some information.

Science fictions had suggested inter stellar travel possible by shredding the organic human parts and by replacing with metal ect. , sending frozen humans to space and de frosting when they arrive to there destinations, sending gene banks in to space and even traveling with the soul.

Answer 6

I have read the answers of others . they are saying that if a time machine is invented only then. but i want to tell u that the budget is not enough to make a time a machine.And if we have a time machine how will it help us to travel to stars. it can only help us to see that can we travel 2 stars or not.if not then the time machine is useless

Answer 7

Think that you must mean planets as stars are too hot/unstable/radioactive to physically land on. NASA are planning a manned mission to Mars right now. To get to other planets beyond this Solar System would take generations involving cryogenics or planned births enroute raising moral & philosophical questions as well as scientific ones.

Answer 8

If mankind ever invents some machine to allow humans to travel light speeds (without dying), I think it's possible, but it would get little funding because there seems to be no purpose in reaching to other galaxies

Answer 9

No unfortunately. The Human Race will become extinct before it ever discovers the required technology.

Answer 10

I hope so - but I seriously doubt we will see this in our life times. Stephen Hawkings says if we don't habitate other planets the human race will die out. Food for thought!

Answer 11

Yes, but with the present rate of technological advance, it will be a few thousand years before it happens.