# How Far Are Stars?

Photo by Michael J. Bennett

This week’s post is a bit of a distraction from the usual business, based on a question I wondered about. Rather than ask Google, I dug in like a nerd to get a more complete picture.

One of my frequent spiels is about the vastness of space, in the context that we can dismiss fantasies about humans traveling to the stars. I do throw in an old-school calculation at the end to reinforce this point, but until then we’ll entertain ourselves with a sense for the scale of the sky we see with our eyes.

When we consider a scale model in which the sun is reduced to the size of a sand grain (about 1 millimeter), the closest neighbor star is about 30 km away. One light year at this scale is about 7 km. But how typical is this yawning gulf in our region of the galaxy? And how far away are the stars we lay eyes on in the night sky, typically?

Before getting to those questions, just how many stars can we see, naked-eye? It depends on the darkness of your sky. According to the Hipparcos catalog, rounding apparent visual magnitudes to the nearest integer, there are two −1 magnitude stars: Sirius and Canopus. Eight more join at magnitude zero; 12 at first magnitude; 71 at second; 192 at third; 622 at fourth; 1909 at fifth; and 5976 at sixth—at which point our eyes run out of steam. A suburban sky might allow fourth magnitude, or roughly 1,000 stars (not all at once, since only half are up at a time). At fifth magnitude, we get about 3,000 (all-sky). At the limit, we tally about 9,000 stars. About half this number would be above the horizon at any given time.

Incidentally, going to space hardly does a thing to improve visibility: the atmosphere is pretty impressively transparent at visible wavelengths (only “eating” about a tenth of a magnitude). I was excited to see the night sky from Mauna Kea on my first observing trip there as a graduate student. Being above 40% of the Earth’s atmosphere, it’s the closest I had been to space. The thing is, low oxygen levels impair visual sensitivity, so when I first went outside it really sucked: I could barely see a thing (eventually dark-adapted, but way slower than at lower elevations). Space is even worse on the oxygen front.

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# To What End?

Image by naturfreund_pics from Pixabay

Recent reflections on the long-term trajectory of the human enterprise have somewhat transformed the way I look at most activities. Specifically, I refer to the dual realizations that on 10,000 year timescales ultimate success is effectively synonymous with true sustainability, and that the human race stands in blatant breach of contract with evolution and ecosystem parameters—fueled by a mad grab of one-time finite resources. The net effect is that most human activities today promote ultimate failure rather than ultimate success.

As such, when evaluating a proposed or ongoing effort, I ask myself the question:

To what end?

This post will examine some of the activities of current society, and evaluate how much sense they make in the context of a post-party future.

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# Life Found on Mars

ESA & MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

No, life has not yet been found on Mars, but imagine waking up to that headline. How would you react? The headline’s font would be huge on print newspapers—maybe one word per page, occupying the first four pages. Some bold papers might even put one letter per page and go so far as to have blank pages for the spaces. The point is, it would be big news.

So I ask again, what would this stir for you?

For me, the swirl would be thick with competing thoughts and feelings, tripping over themselves to get out. First would be the raft of questions stemming from pure curiosity. Is it DNA-based? Is it a separate start, or do we share some ancient microbial ancestor—possibly shuttled from one body to the other following a meteoric impact? What lessons can we learn about how life forms? Can we get the discovered lifeforms to call us Mama or Dada? Will they make good pets?

One can imagine the discovery team, whether at NASA or elsewhere, ecstatic with joy. The entire exploration establishment around the planet would likely be giddy. SETI folks would probably be unable to chew for a while, wearing fixed grins.

I would share many of these same reactions, for the pure joy of discovery and the novel opportunity to re-examine what it means to be a part of life on Earth. But then it dawns on me just how devastating the news might actually be for the human race.

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# You Call this Progress?

One of the prevailing narratives of our time is that we are innovating our way into the future at break-neck speed. It’s just dizzying how quickly the world around us is changing. Technology is this juggernaut that gets ever bigger, ever faster, and all we need to do is hold on for the wild ride into the infinitely cool. Problems get solved faster than we can blink.

But I’m going to claim that this is an old, outdated narrative. I think we have a tendency to latch onto a story of humanity that we find appealing or flattering, and stick with it long past its expiration date. Many readers at this point, in fact, may think that it’s sheer lunacy for me to challenge such an obvious truth about the world we live in. Perhaps this will encourage said souls to read on—eager to witness a spectacular failure as I attempt to pull off this seemingly impossible stunt.

The (slightly overstated) claim is that no major new inventions have come to bear in my 45-year lifespan. The 45 years prior, however, were chock-full of monumental breakthroughs.

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# Survey the People

The futuristic survey (covered in last post) has attracted about 1300 respondents, 900 from DtM, 300 from the Energy Bulletin (now Resilience.org), and a smattering from other places.

I will ultimately be sharing the results, but the habitual readers of the aforementioned sites are perhaps not representative of the population at large.

Thus I would like your help in pushing this out to a broader population.  See if you can get your friends and family members to take the survey, and perhaps even pass the link on to their friends, etc.  I’ve never done this sort of thing before, so do not know what to expect.  But let’s give it a try, yeah?

Thanks for your help—should be very interesting.

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# Futuristic Physicists?

www.dvdtoponline.com

One day, sitting around with a group of undergraduate physics students, I listened as one made the bold statement: “If it can be imagined, it can be done.” The others nodded in agreement. It sounded like wisdom. It took me all of two seconds to violate this dictum as I imagined myself jumping straight up to the Moon. I may have asked if the student really thought what he said was true, but resisted the impulse to turn it into an impromptu teaching moment. Instead, I wondered how pervasive this attitude was among physics students and faculty. So I put together a survey and in this post report what I found. The overriding theme: experts say don’t count on a Star Trek future. Ever.

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# Ruthless Extrapolation

We humans owe much of our success to our ability to recognize patterns and extrapolate trends to anticipate a future state. My cats, on the other hand, will watch a tossed toy mouse travel toward them across the room—getting ever-bigger—all the way until it smacks them between the eyes (no, they’re not strapped down—I’m not that sort of scientist). But far beyond an ability to avoid projectiles, our ancestors were able to perceive and react to changes in local food and water supplies, herd movements, seasonal cues, etc. Yet this fine tool can be over-used, and I see a lot of what I call ruthless extrapolation. In almost every case, extrapolation works until it doesn’t.  When the fundamental rules of the game change, watch out!

As with many aspects of human behavior, some of the finest commentary on the matter is served up by The Simpsons. In one episode, Lisa Simpson is taken to the orthodontist to evaluate whether or not she needs braces. The “doctor” runs a simulation based on current growth rates, producing an alarming graphic of teeth gone wild.

Image obtained from saucesome.net

Marge shrieks and is ready to do whatever it takes to protect her daughter against this cruel fate. Extrapolation can, of course, be used to argue both for impending doom or future prosperity—sometimes based on the same data. I started this blog with an extrapolative foil to demonstrate the insanity of continued physical growth, in fact. A tangential follow-up illustrated the hopelessness of differentiating a steady-state energy future from an energy crash using current data (although a continued exponential rise is already a poor fit).

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# Stranded Resources

A few weeks back, I made the case that relying on space to provide an infinite resource base into which we grow/expand forever is misguided. Not only is it much harder than many people appreciate, but it represents a distraction to the message that growth cannot continue on Earth and we should get busy planning a transition to a non-growth-based, truly sustainable existence. To prove what a distraction it is, I will distract myself again this week with another space post. This time, true to the brand, I will do the math on why the infinite resources of space appear to be of questionable use to our human enterprise.

Part of my motivation comes from the bruised, and bruising comments in reaction to the Why Not Space? post. The faith is strong that technologies are already in hand and that we just need NASA to get out of the way so the commercial bounty of the sky will open up and we’ll finally be off to the races. I myself refrained from ruling out such a future, but the mere suggestion that we may fail to expand into space was clearly considered by many to be ridiculous—as if such a fate is predestined: as sure as the sun will tomorrow. Sociological impulses tugged at my physicist bones, tempting me to study exactly how such an unshakable faith has been implanted in so many obviously smart people. For these folks, the arc of the future is as sure as the historical progression from the Dark Ages until now. Wait? Was there something before the Dark Ages? Something grand? Alas, my history fails me.

Leaving the sociology aside—but before we get busy with the math—I’ll share the story that during the comment firestorm, an individual contacted me from NASA headquarters (not to revoke my funding, thankfully), offering thoughtful perspectives on space policy. The part I can’t shake is the statement that it takes decades of serious research to answer two simple questions: “Can humans live and work in space for the long term?” and “Can an economically viable activity be found in space?” Opinions aside, these are open questions, and have been for some time. We have no proof—or even firm expectation—that either is practical or possible.

## Lots of Stuff

Around the time of the final U.S. Space Shuttle flight, a NASA official was asked in a radio interview to explain what was left to inspire young kids about space. The answer was that mining asteroids and the Moon offered a new grand challenge to inspire our kidlets. Granted, space mining probably is a bit more inspiring than off-shore drilling or coal mining as a career choice. It’s got space in it. But are we really serious about getting materials from other bodies within the solar system?

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# Why Not Space?

[An expanded treatment of some of this material appears in Chapter 6 of the Energy and Human Ambitions on a Finite Planet (free) textbook.]

Ask a random sampling of people if they think we will have colonized space in 500 years, and I expect it will be a while before you run into someone who says it’s unlikely. Our migration from this planet is a seductive vision of the future that has been given almost tangible reality by our entertainment industry. We are attracted to the narrative that our primitive progenitors crawled out of the ocean, just as we’ll crawl off our home planet (en masse) some day.

I’m not going to claim that this vision is false: how could I know that? But I will point out a few of the unappreciated difficulties with this view. The subtext is that space fantasies can prevent us from tackling mundane problems whose denial could result in a backward slide. When driving, fixing your gaze on the gleaming horizon is likely to result in your crashing into a stopped car ahead of you, so that your car is no longer capable of reaching the promised land ahead. We have to pay attention to the stupid stuff right in front of us, as it might well stand between us and a smart future.

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