by Paul Gilster | Jul 6, 2011 | Culture and Society |
A good futurist can come up with all kinds of outcomes for humanity, but for those of us consumed by space exploration, a recent article in The Economist sketches a particularly bleak possibility. Forget about the stars. For that matter, forget about Mars, even the Moon. The new reality is emerging in the symbolic end of the Space Shuttle program and the eventual de-orbiting of the International Space Station. It’s a reality based on a space program that fares no higher than geostationary orbit and the growing technosphere that encloses us like a planetary ring.
The End of the Space Age is a cautionary tale about an all too real possibility, one that dismisses those anxious to move into the Solar System as ‘space cadets,’ while invoking the space ideas of the 1950s and 60s as an almost surreal excursion that quickly gave way to the outright fantasy of ‘Star Trek.’ The Economist will have none of the old optimism, the vision of ever expanding humanity pushing out to build an infrastructure throughout the inner planets and beyond. The view is stark. Declaring that the Space Age is probably over, the article adds:
The future… looks bounded by that new outer limit of planet Earth, the geostationary orbit. Within it, the buzz of activity will continue to grow and fill the vacuum. This part of space will be tamed by humanity, as the species has tamed so many wildernesses in the past. Outside it, though, the vacuum will remain empty. There may be occasional forays, just as men sometimes leave their huddled research bases in Antarctica to scuttle briefly across the ice cap before returning, for warmth, food and company, to base. But humanity’s dreams of a future beyond that final frontier have, largely, faded.
I bring you this counterbalance to our usual explorations as a way of pointing out that missions to the stars — or even the outer planets — are by no means inevitable, even if people like myself operate with a conviction that they will happen. One of the things that confounds predictions about when and if a true interstellar mission will fly is that history does not always follow a straight path. Cultures can turn inward, technologies can be turned to frivolous ends or disappear altogether, learning can be all but lost as it was for a lengthy period in the European dark ages.
But what The Economist is talking about isn’t a new period of darkness as much as a coming era of content with our own planet. After all, what the Space Age has delivered so far is impressive, and not just in our far-flung robotic missions. Out there at 36,000 kilometers where the telecommunications satellites orbit and extending down to low Earth orbit, our satellites give us global positioning systems and finely tuned weather forecasts, not to mention spy capabilities that change the equations of war. What if the sheer cost of space and growing public indifference put an end to further explorations?
An exhausted world economy, thinks The Economist, will pull us back to Earth:
With luck, robotic exploration of the solar system will continue. But even there, the risk is of diminishing returns. Every planet has now been visited, and every planet with a solid surface bar Mercury has been landed on. Asteroids, moons and comets have all been added to the stamp album. Unless life turns up on Mars, or somewhere even more unexpected, public interest in the whole thing is likely to wane. And it is the public that pays for it all.
There are answers to all these ideas, but the point is that those of us who believe in a human future throughout the Solar System are going to find ourselves challenged at every turn to explain why such an outcome is even possible, much less desirable. We’re at that juncture where government space efforts are being supplanted by commercial ventures like those of Elon Musk and Sir Richard Branson, a time when we have to find something on which to hang the space program beyond expensive space tourism. Maybe Robert Zubrin has found one way forward through his suggestion of using a bevy of SpaceX heavy-lift vehicles to haul materials to Mars for an early human outpost there. But SpaceX has to succeed with that vehicle first.
As commercial space efforts move forward, a broader defense of a human future in space has to take the long-term view. Given the dangers that beset our planet, from ecological issues to economic turmoil and the potential for war, can we frame a solution that offers a rational backup plan for humanity? Planetary self-defense also involves the need for the tools to alter the trajectory of any object with the potential to strike the Earth with deadly force, and that means expanding, not contracting, our space-borne assets. Such work is not purely technical. It also teaches the invaluable lesson of multi-generational responsibility and holds out the promise of frontiers. Such challenges have enriched our early history and provide us a clear path off our planet.
We’re also a curious species, and it’s hard to see us pulling back from the challenge of answering the crucial question of whether we are alone in the galaxy. There is a huge gap, as The Economist points out, between where we stand with space technology today and where we fantasized being as we looked forward from the Apollo days. But a case can be made for steady and incremental research that gives us new propulsion options and broadens our knowledge of how life emerges even as it protects our future. A future that includes gradual expansion into space-based habitats and the exploitation of our system’s abundant resources is an alternative to The Economist‘s vision, and it’s one the public needs to hear. The infrastructure that it would build will demand the tools and the skills to move ever deeper into our system and beyond.
by Paul Gilster | Jul 5, 2011 | Uncategorized |
Is the universe at the deepest level grainy? In other words, if you keep drilling down to smaller and smaller scales, do you reach a point where spacetime is, like the grains of sand on a beach, found in discrete units? It’s an interesting thought in light of recent observations by ESA’s Integral gamma-ray observatory, but before we get to Integral, I want to ponder the spacetime notion a bit further, using Brian Greene’s superb new book The Hidden Reality as my guide. Because how spacetime is put together has obvious implications for our philosophy of science.
Consider how we measure things, and the fact that we have to break phenomena into discrete units to make sense of them. Here’s Greene’s explanation:
For the laws of physics to be computable, or even limit computable, the traditional reliance on real numbers would have to be abandoned. This would apply not just to space and time, usually described using coordinates whose values can range over the real numbers, but also for all other mathematical ingredients the laws use. The strength of an electromagnetic field, for example, could not vary over real numbers, but only over a discrete set of values. Similarly for the probability that the electron is here or there.
By ‘limit computable,’ Greene refers to ‘functions for which there is a finite algorithm that evaluates them to ever greater precision.’ He goes on to invoke the work of computer scientist Jürgen Schmidhuber:
Schmidhuber has emphasized that all calculations that physicists have ever carried out have involved the manipulation of discrete symbols (written on paper, on a blackboard, or input to a computer). And so, even though this body of scientific work has always been viewed as involving the real numbers, in practice it doesn’t. Similarly for all quantities ever measured. No device has infinite accuracy and so our measurements always involve discrete numerical outputs. In that sense, all the successes of physics can be read as successes for a digital paradigm. Perhaps, then, the true laws themselves are, in fact, computable (or limit computable).
If computable mathematical functions are those that can be successfully evaluated by a computer using a finite set of discrete instructions, the question then becomes whether our universe is truly describable at the deepest levels using such functions. Can we reach an answer that is more than an extremely close approximation? If the answer is yes, then we move toward a view of physical reality where the continuum plays no role. But let Greene explain the implications:
Discreteness, the core of the computational paradigm, should prevail. Space surely seems continuous, but we’ve only probed it down to a billionth of a billionth of a meter. It’s possible that with more refined probes we will one day establish that space is fundamentally discrete; for now, the question is open. A similar limited understanding applies to intervals of time. The discoveries [discussed in Greene’s Chapter 9] which yield information capacity of one bit per Planck area in any region of space, constitute a major step in the direction of discreteness. But the issue of how far the digital paradigm can be taken remains far from settled.
And Greene goes on, in this remarkable study of parallel universes as conceived by physics today, to say that his own guess is that we will find the universe is fundamentally discrete.
All of this gets me to the Integral observatory. Because underlying what Greene is talking about is the fact that the General Theory of Relativity describes properties of gravity under the assumption that space is smooth and continuous, not discrete. Quantum theory, on the other hand, suggests that space is grainy at the smallest scales, and it’s the unification, and reconciliation, of these ideas that is wrapped up in the continuing search for a theory of ‘quantum gravity.’
New results from Integral can’t give us a final answer, but they do put limits on the size of the quantum ‘grains’ of space, showing us that they must be smaller than at least some theories of quantum gravity suggest. All of this comes courtesy of a gamma-ray burst — specifically, GRB 041219A, which took place on the 19th of December back in 2004. This was an extremely bright GRB (among the top one percent of GRB detections), and it was bright enough that Integral was able to measure the polarization of its gamma rays. The so-called ‘graininess’ of space should affect how gamma rays travel, changing their polarization (the direction in which they oscillate).
In fact, high-energy gamma rays should show marked differences in polarization from their lower-energy counterparts. Yet studying the difference in polarization between the two types of gamma rays, Philippe Laurent of CEA Saclay and his collaborators found no differences in polarization to the accuracy limits of the data. Theories have suggested that the quantum nature of space should become apparent at the Planck scale: 10-35 of a meter. But the Integral observations are 10,000 times more accurate than any previous measurements and show that if quantum graininess exists, it must occur at a level of at least 10-48 m or smaller.
“Fundamental physics is a less obvious application for the gamma-ray observatory, Integral,” notes Christoph Winkler, ESA’s Integral Project Scientist. “Nevertheless, it has allowed us to take a big step forward in investigating the nature of space itself.”
Indeed. Philippe Laurent is already talking about the significance of the result in helping us rule out some versions of string theory and some quantum loop gravity ideas. But many possibilities remain. The new findings that will come from further study will not displace earlier laws so much as extend them into new realms. In this sense past discoveries are rarely irrelevant, and it is a tribute to the coherency of physics that new perspectives so often incorporate earlier thinking. Thus Newton is not displaced by Einstein but becomes part of a more comprehensive synthesis.
Image: Integral’s IBIS instrument captured the gamma-ray burst (GRB) of 19 December 2004 that Philippe Laurent and colleagues have now analysed in detail. It was so bright that Integral could also measure its polarisation, allowing Laurent and colleagues to look for differences in the signal from different energies. The GRB shown here, on 25 November 2002, was the first captured using such a powerful gamma-ray camera as Integral’s. When they occur, GRBs shine as brightly as hundreds of galaxies each containing billions of stars. Credits: ESA/SPI Team/ECF.
Greene points out in The Hidden Reality that Isaac Newton himself never thought the laws he discovered were the only truths we would need. He saw a universe far richer than those his laws implied, and his statement on the fact is always worth quoting:
“I do not know what I may appear to the world, but to myself I seem to have only been a boy playing on the seashore, diverting myself in now and then finding a smoother pebble or prettier shell than ordinary, whilst the great ocean of truth lay before me all undiscovered.”
The impressive Integral results offer us data that may one day help in the unification of quantum theory and gravity. Thus the distant collapse of a massive star into a neutron star or a black hole during a supernova, the apparent cause of most GRBs, feeds new material to theoreticians and spurs the effort to probe even deeper. In the midst of this intellectual ferment, I strongly recommend Greene’s The Hidden Reality as a way to track recent cosmological thinking. I’ve spent weeks over this one, savoring the language, making abundant notes. Don’t miss it.
For more, see Laurent et al., “Constraints on Lorentz Invariance Violation using integral/IBIS observations of GRB041219A,” Physical Review D, Vol. 83, issue 12 (28 June, 2011). Abstract available.
by Paul Gilster | Jul 1, 2011 | Astrobiology and SETI |
By Larry Klaes
Tau Zero journalist Larry Klaes gives us a look at a NASA publication whose authors tackle the biggest questions imaginable for our culture. Usefully, this volume, whose authors include major names in fields ranging from astrophysics to cultural evolution, is available online at no charge. As Larry points out, it deserves wide readership, for the issues of our place in the universe and how we respond to potential extraterrestrial contact via SETI will guide our future, both on Earth and in space.
It is often difficult to get a wider perspective on existence, especially when you and the rest of your species have been stuck in one place for all but the smallest and most recent of times. This has certainly been the case with the species known as humanity. While a few ancient philosophers guessed that we live on a world surrounded by an immense amount of stars and space, it has only been in the last few centuries that both the scientific and general communities came to accept this state of existence as a fact. It has been an even shorter period of time – mere decades – since we have sent our mechanical emissaries and a relative handful of actual humans into the nearest regions of our cosmic neighborhood.
Why are we fascinated with a realm that is unimaginably vast, difficult to attain, and even dangerous? Does that which occurs in space affect life on Earth, and in what ways? Are there other intelligent beings in the Universe and what may result if we should ever encounter one another? What will be the fate of all life far down the cosmic road?
Tackling these mighty subjects is a book titled Cosmos & Culture: Cultural Evolution in a Cosmic Context (NASA SP-2009-4802), edited by Steven J. Dick and Mark L. Lupisella. Most NASA publications deal with the illustrious history of the US space program, often going into great detail about the people, processes, and machines. Cosmos & Culture looks at the ultimate reasons why we want to explore and settle space and how that decision will affect our society and species.
Image: The sky confronts us nightly with the immensity of the cosmos. Here we’re looking at southern skies from the vantage of the Cerro Tololo Inter-American Observatory atop a Chilean mountain. Look carefully and you’ll see both the Small and Large Magellanic Clouds, along with the great band of the Milky Way at right and the Southern Cross just to the right of the 4-meter telecope called Blanco. Credit: Roger Smith, AURA, NOAO, NSF.
This topic is refreshing to see in a work from the space agency: With many space missions, one can sometimes get only vague platitudes as to why we seek to know what is out there. This sometimes creates a sense that the rest of the Universe — and why science goes about studying it — has no real, immediate relation to human society. With Cosmos & Culture, professionals from a variety of fields look at the Universe from their particular perspectives and attempt to bring it all together to show why and how the evolution and development of the Cosmos is anything but esoteric for our own biological and cultural development.
The result is a combination of fascinating ideas that go beyond the usual NASA literature, though sometimes they tend to get rather bogged down in their own explanations. Add to this the fact that many of the ideas presented in this book are admittedly speculation and one tends to worry that the results will be akin to reading a tract on a new form of religion. Nevertheless, the authors are sincere and excited in their efforts here and one knows that even if some of the answers are not what the questioners assumed or hoped for, they do succeed in bringing home the fact that we are an integral part of a much larger world than most of our forbearers could even consider. This is an idea that could literally and ultimately be the difference between either evolution or extinction for humanity.
One of the more important themes in this book is that of extraterrestrial life. The authors on this subject want to know if alien beings exist for three main reasons:
- To see how other creatures have evolved
- To find out if we can communicate with each other
- To understand how our interactions will change us as we expand into the galaxy and beyond.
The authors examine not only what kind of minds could exist besides our own and how they might affect us on various levels, but how our attempts and plans to explain ourselves and our world to alien intelligences shape our perspectives and ultimately our very existence in the process. As Douglas A. Vakoch, the Director of Interstellar Message Composition at The SETI Institute, says in Chapter 12: Encoding Our Origins:
“Although the focus of SETI is on making contact with intelligence beyond Earth, the exercise of portraying ourselves in interstellar messages provides us with an opportunity to cultivate greater intelligence on our own planet.”
Image: Another look at southern skies, with the Milky Way and the Large and Small Magellanic Clouds framed by cacti from the Atacama desert in this superb photograph by Stéphane Guisard.
Though some chapters are easier to digest than others at a first sitting, Cosmos & Culture makes for a fascinating read. One is guaranteed to learn quite a few new facts and concepts even from a brief swim in these waters thanks to the variety of professionals who have come together to share their ideas. One also realizes how important this book is for our species to grasp the grander picture of reality, for we cannot even afford to pretend to be the focal point of existence any more if we want to avoid societal stagnation or worse. Cosmos & Culture does not claim to have all the answers, but this collection has certainly pointed the way towards some very interesting paths.
Cosmos & Culture: Cultural Evolution in a Cosmic Context is available online.
