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27 May, 2010

Time, Relativity, Time Travel, and the Great Puzzle of Why the Sun Rose This Morning

There's something wrong with my notion of time.

I used to think it was all subjective - by which I meant relative to one's frame of reference, as general relativity tells us. I am more than happy to accept all the experimental evidence that says moving very fast, or being near a large mass, will slow down the passage of time relative to an observer outside your frame of reference. There is so much evidence for general relativity that it would be ludicrous not to accept it. Yet a simple observation of my own tells me that there must be more to the story than that.

And this is it: the Sun rose this morning. I know that because I saw it.

The problem is that it should not have done. The Sun should not be there at all. The Sun and the Earth were formed at about the same time, some 4.5 billion years ago. However, the mass of the Sun is about 330,000 times that of the Earth. Relatively speaking, time will run a bit more slowly for the Sun than for the Earth. But, after 4.5 billion years, all those nanosecond differences will add up. Yet Earth and Sun seem to be here together. We have both arrived at today at the same time.

So my notion of time - and/or my notion of what general relativity is saying - must be wrong. In fact, the same goes for special relativity too. I cannot account for why anything moving fast relative to me doesn't just wink out of existence. Because its time is slowed down, I should move into its future, it should move into my past, and we should not be able to perceive each other in our respective presents. After all, I know from experience that I cannot see the future, or the past.

So, okay, the fact that relative gravitational potential, or acceleration, or velocity, affects the rate at which time passes for different 'observers' seems to have nothing to do with the way time is actually passing for us all. I can live with that. In fact, I've seen something very like it somewhere else. The speed of light is quite similar. This is a constant and, all intuition aside, light travels at the same velocity (c) relative to you, whatever speed and direction you are travelling relative to its source. What does happen to light, though, is that its frequency shifts. If you are approaching a source of light very fast, it still hits you at exactly c but its frequency is shifted higher - towards the blue end of the spectrum. If you are racing away from the source, light still catches you at exactly c, but now its freuency is lower - shifted towards the red end of the spectrum.

What if time behaves like light? What if the rate of passage of time is also constant? Then, whatever we were doing in the Universe, time would always affect us the same way. But, accelerations, gravitational fields, and relative velocities lead to us perceiving a shift in something equivalent to the frequency of time. Let's call it time's 'colour'. A high gravitational potential, shifts time's colour towards the red end of its spectrum.

This notion (although it explains my problem with time) is an intuitively difficult one because what we normally think of as time - that thing that measures the intervals between ticks of a clock - isn't really time at all. It is just the colour of time. Real time, the thing that has its colour shifted and which ensures the continued coexistence of everything in the present, must be something else. Maybe we should call it 'persistence' or (to borrow a word from H. G. Wells) 'duration'?

So time is a kind of universal persistence and what I used think was time is just the colour of this persistence.

Am I happy now? No, not really. For a start, shifting the colour of persistence is analogous to shifting the colour of light (and is effected in exactly the same ways). So, by the same analogy, there can be no time travel. Shifting the colour of light does not affect its speed. The rate of persistence will be constant regardless of relativistic effects on its colour. You can age less (or more) than other things in the Universe by manipulating your speed, acceleration, or proximity to mass, but you do not change your place in persistence with respect to the rest of the Universe. That's why fast things do not blink out of existence for me. We are persisting at the same rate, even though we are aging at different rates. (Even dragging the exit of a wormhole around at near light-speed won't do the trick any more, because entrance and exit persist at the same rate, the exit may end up younger than the entrance but they will still be there at the same point in persistence at the end of it all!)

Are there any physicists out there who can tell me why all this is wrong and also explain why I saw the Sun this morning?

14 May, 2010

Review: Epitaph Road by David Patneaude

(This review first appeared in the New York Journal of Books on 12th May, 2010)

Epitaph Road is the latest in a string of successful young adult novels by David Patneaude. In 2067 a world reeling from recent nuclear brinkmanship between the USA and China is suddenly devastated by a virus that kills almost every male person on the planet. Only those males at sea or in remote places survive.
Thirty years later, the world is populated and dominated by women. There are a few more males, but strict birth control laws ensure that the male population cannot rise above 5%. It is a world free of much petty crime and war but one in which the remaining males are subjugated and controlled, and the women in power have all the vices that political elites have always had. 
Kellen Winters is fourteen in 2097, the son of one of the few survivors of the plague they called Elisha’s Bear. He lives with his absentee mother, an important person in the new North American government, and dreams of leaving one day to join his father, who lives as a “loner” among male “throwbacks” on a kind of reservation. He is preparing for his citizenship exams and coping with the oppression and subjugation that is the role of all males, when he and two female classmates stumble on some information that leads them to delve into the origins of the plague that changed the world and which still recurs from time to time. What they uncover sends them on a journey to find his father and warn him about a potential new outbreak. But powerful forces don’t want Kellen to reach the throwbacks, and police and other agencies are searching for him as he and his friends stumble upon another shocking and deadly secret. 
Epitaph Road is a straightforward adventure story in which a group of youngsters fight the forces of an oppressive and hypocritical adult world. It has good pacing, is nicely written, and the adventure runs its course as it should to its proper ending. Yet it is a most unsatisfying story, with two major flaws that spoiled it for me.
The first is the aftermath of the plague. Almost overnight, half the population of the world dies. And it is the male half, the half that hogs most of the power, dominates all industries except the lower-paid service industries, and has a near stranglehold in areas such as engineering, construction, power, transportation, communications, and so on. Yet, the world carries on, civilization carries on as if nothing has happened. The supply of electricity keeps flowing, the farms and food distribution keeps going, the communications networks stay up, the domestic water and sewage networks still operate, and billions of bodies are buried. There is no mass starvation; no millions dying in that first, unheated winter; no disease; no cessation of oil supplies; no massive shortage of doctors. Within a handful of years, countries have merged, a new world political order is established, new education systems are put in place, and massive social change is underway. You might think that, possibly by 2067, there is sexual equality and the work and power disparities of today no longer exist, but according to the story, that is not the case. If anything, male dominance is worse by then.
With a pinch of suspended disbelief, you might get past this issue, but it is the kind of “world building” problem that leaves me very uncomfortable. Worse, however, is the fact that the bulk of the story is set in 2097—almost a hundred years from now—but no technology seems to have advanced beyond today’s level. True, the desktop computers have touch screens, the smartphones are called “e-sponders,” and electric cars are commonplace (although the throwback men still drive old petrol cars), but there are no new technologies.  
The idea that civilization could progress for 90 years without radical new technologies appearing is just incredible. Even if we suppose that technical innovation ended in 2067 when the men died, we should still expect fifty more years’ worth. For example, the Internet is just twenty years old as you read this. It was barely known to the world at large before 1995. Yet the Web and texting (a technology which is about the same age as the Web) are supposedly still the technologies in use by kids in Epitaph Road, eighty-seven years from now. 
This is such a massive failure of the imagination, and introduces such a jarring credibility problem, that the question has to be asked: Why didn’t Patneaude set the book in the present? Without more than this minimal nod in the direction of world building, this is not science fiction. So why not make the date 2007 instead of 2097 and let this become an alternative history novel? 
It is a young adult novel, and is intended for children, but that is no excuse for not treating his readership with more respect. The description and development of the book’s main characters, their complex feelings and motivations, is well up to scratch, the plot is simple and easily anticipated but nicely executed and suited to the genre. However, the book is badly let down by the credibility of a major plot element and the complete failure to present a believable future world.

03 May, 2010

Review: Cro-Magnon by Brian Fagan

(This review first appeared in The New York Journal of Books on 2nd May 2010.)
By any standards, Brian Fagan is a leading authority on archaeology, and, with 46 books on the subject to his credit, he is among the world’s leading popularizers of the field. In Cro-Magnon, he gives us an easily digested round-up of what is known about the pre-history of modern humans in Europe.

Fagan presents an essentially chronological account, starting with the Neanderthals who were already present in Europe when modern humans arrived, and taking a brief detour to look at the evolution of hominins in Africa. From the arrival of Cro-Magnons around 45,000 years ago until the spread of farming in Europe, about 8,000 years ago, the book traces the movements and developing cultures of these people who were the first homo sapiens to settle the continent. It has a good index and an extensive list of further reading in the Notes section.

If you live in Europe, or are of European descent, then the Cro-Magnons were almost certainly your direct ancestors. Fagan digests and presents for us the extremely complex evidence that reveals population movements and social conditions, without burdening us with details or much controversy. This evidence is mostly archaeological—the bones, human and animal, that were left behind, the stone tools, the excavations, and the paintings and carvings. But he also makes much use of climatological data, studies of modern and recent stone-age peoples, and recent genetic studies, again, sparing us the arguments and supplying only the conclusions.

Fagan works in a field that is massively interpretative. Controversies abound—especially in the assessment of purely social, spiritual, or linguistic aspects of ancient peoples. Yet this reviewer thinks it is a strength of his approach that he delivers what he feels is the most likely interpretation, given a broad, eclectic, yet conservative, summary of the data from many disciplines, merely indicating where there may still be some disagreement among experts. It allows him to present an extended and coherent narrative that makes sense of the whole story of Cro-Magnon settlement in Europe.

And the way he tells it, it was a long, hard struggle. Europe, for most of the time that Cro-Magnons carved out a place there, was a bitterly cold, hostile environment, more akin to Northern Siberia or Canada than to the temperate land we know today. Frozen tundra and barren steppes were what greeted those first immigrants. Yet the Neanderthals had survived there for nearly 200,000 years when we arrived. It is typical of Fagan’s non-controversial approach that he doesn’t indulge in lurid speculation about how modern humans drove the Neanderthals to extinction. It was a slow and gradual process that took place over many thousands of years. In Fagan’s view the Neanderthals simply continued to live their lives as they always had, only with Cro-Magnons hunting the same territories, times just grew harder, until their already-marginal existence was gradually pushed beyond the brink.

Yet, while the absence of detail such as the minutiae of debates about dating and statistical analyses allows Fagan to present the bigger picture with bold strokes, it also leaves you wondering about some of his assertions. He is, for example, very firm on what was men’s work and what was women’s work. How much of that is in the actual evidence, and how much is imported from modern anthropological studies, or even modern prejudices?  And the speculations about whether Neanderthals danced seem fanciful and based on slender evidence (which appears, from what is said, also to be consistent with the hypothesis that they wrestled).

And it isn’t as if there was no room for more detail or more discussion. The book proceeds at the painfully slow pace of a modern TV documentary, with considerable repetition and often tedious dramatizations of life in the late Ice Age. The material in the book could have been presented in perhaps a quarter of the number of pages if not for the slow, repetitious style. 

The book proceeds at a measured pace, to put it kindly, and, while clearly written, the language used is often clichéd and itself repetitive. (There were several points where I thought if I read the words “bestiary” or “tool kit” one more time, I would throw the book down and jump on it.) Which is disappointing because there are sections—like the discussion of Cro-Magnon art near the end—where Fagan writes with fascination and insight. If the whole book had been like that, it would have been such a joy to read. As it was, the book provides a clear, pain-free summary of what is known about the earliest Europeans—it just happens to be a bit slow.

It is a sign of the rate of change in this field that, even as Cro-Magnon comes to press, DNA analysis of a finger bone found in a southern Siberian cave suggests that a third hominin species may have co-existed with Cro-Magnons and Neanderthals in that region. How would the presence of another human line affect the conclusions in Cro-Magnon? Only future editions will tell.

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