Tuning in on Noise?

xkcd-904It’s a bit off-topic for the series, but I can’t even go to Google now without being reminded of the World Cup and soccer this, soccer that. (Apologies to non-Americans who know the sport as football—but don’t get me started on football!) I have often wondered: given characteristic low score values, is soccer anything more than Poisson noise? When discussing this with colleagues, one pointed me to this XKCD comic, reproduced at right.

Any random process that produces discrete events in some time interval, with uniform probability per unit time follows a Poisson distribution. When the number of events becomes large, the distribution tends toward a Gaussian (normal) distribution.

My thesis is that soccer is an amalgam of random processes whose net effect produces rare events—those more-or-less unpredictable events spread more-or-less uniformly in time. Whether a good or bad bounce off the bar, a goal keeper who may or may not prevent a goal, a referee who may or may not see an illegal action, a pass that may or may not be intercepted, and on and on: the game is full of random, unpredictable events. So I expect soccer to behave similarly to a Poisson process and follow a Poisson distribution. By extension, I will claim that the attention devoted to the World Cup is founded on flimsy numerology and might even be called a tremendous waste of time and money.

Normally I allow comments on Do the Math for ten days after each post. I’ve tackled some controversial topics and stirred up emotional responses. Yet I predict that the outrage generated by my insinuation that watching soccer is a waste of time will absolutely dwarf the reactions to my saying that we may not be looking at a space-faring future, or that indeed we may face collapse of civilization. To the extent that this (untested) prediction is true, it would seem that soccer is more important than the fate of the world, in the eyes of many. Scary, if true. [After reconsideration, I enabled comments, but I won't have time to vet and respond with my usual level of attention.]

But getting back to soccer numerology, my question becomes: given a final score (which is taken to be the ultimate “truth” of the match) how likely is it that the victor is actually a better team?

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Plans to Put PV to Pasture?

PV out to pasture?A colleague pointed me toward an article in the LA Times last week, which lays out a plan to remove financial incentives legally bestowed on solar photovoltaics (PV) to the detriment of utility power companies. The plan is spearheaded by the Koch brothers and their political action group, Americans for Prosperity.

In summary, they target two laws that give a big boost to solar: net metering, and renewable mandates. Both impart crucial advantages to solar installations that can change the economics by a large factor.

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Prolonged Absence

The cessation of regular blog posts has prompted a number of folks to ask if I still live and breathe. Several reasons contribute to the silence. Primarily, most of what I set out to do and say on Do the Math has been covered. How many times can I calculate total tidal power available? I’ve expressed views on our precarious trajectory with respect to finite resources, touched on the psychology of major change and sacrifice, and shared personal explorations in reducing energy/resource footprints at home. While some of this continues (look for a post on nickel-iron batteries soon), for the most part it’s already all there.

The second factor is that the research, education, and administration components of my life (i.e., my job) are demanding significant attention. This has generally been true all along, but the administrative burden has skyrocketed of late due to my role as vice chair of the physics department at UCSD since July 2013. Perhaps as I climb up the learning curve, I’ll find more “hobby” time in the months ahead.

While I am sharing personal news, two things of note: 1) My efforts to write and speak about energy and resource use to a broad audience has resulted in UCSD awarding me the Outstanding Faculty Sustainability Award for 2014. This despite the fact that I don’t know what sustainability means (suspecting that none of us really do), and that very little of my efforts have been directed at the UCSD campus.  All the same, I am as pleased as I am surprised by the recognition.  2) While not related to Do the Math, I encourage you to check out this stunning photo taken by Dan Long capturing our recent laser ranging efforts during the April 15 lunar eclipse.  This is a real photo, taken through a C-11 telescope with a focal reducer (700 mm, f/2)—the outgoing laser beam has not been artificially superimposed. Normally it is really difficult to get a picture of our faint beam heading toward the Moon, because the Moon is so glaringly bright. The eclipse provided a great photo-op, and also a means to test the hypothesis of dusty reflectors. To me, this shot is just gorgeous. But I have more invested in it than the average Joe: this picture serves as a visual representation of a key focus in my life over the last 14 years—so of course I’m enamored.

A Physics-Based Diet Plan

homer-donutThe holiday season is upon us, and for many, this translates into a marked uptick in the consumption of tasty food treats. I’m no different, and can really pack it in on such occasions. For instance, the day after Thanksgiving this year, I stepped on the scale to find myself about 5 pounds (~2 kg) above normal weight. I kicked in my diet plan, and by Monday morning (3 days later) I was back to normal. Resume course. I use a simple formula, backed by physics, that works every single time. The topic is Do-the-Math-relevant for two reasons: it applies quantitative physics to everyday life, and it touches on attitudes relevant to energy/resource conservation.

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The Already-Written Future?

thumbnail as it appeared in NYT

thumbnail from NYT

As a rejoinder to my piece a couple weeks ago (not really), the New York Times published an article on population growth, and why we need not worry. The problem—and solution—is all in our head.  The bottom line was that we have always transformed our ecosystem to provide what we need, and in so doing have pushed the carrying capacity along with our growing population. In fact, the author says, “there really is no such thing as a human carrying capacity.” And he goes on to ask, “why is it that highly trained natural scientists don’t understand this?”

Clearly there is a misunderstanding, but I’ll side with the natural scientists, naturally. The succinct answer is that natural scientists are not comfortable with ruthless extrapolation of past trends.

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The Real Population Problem

Sometimes considered a taboo subject, the issue of population runs as an undercurrent in virtually all discussions of modern challenges. Naturally, resource use, environmental pressures, climate change, food and water supply, and the health of the world’s fish and wildlife populations would all be non-issues if Earth enjoyed a human population of 100 million or less.

The subject is taboo for a few reasons. The suggestion that a smaller number would be nice begs the question of who we should eliminate, and who gets to decide such things. Also, the vast majority of people bring children into the world, and perhaps feel a personal sting when it is implied that such actions are part of the problem. I myself come from a long line of breeders, and perhaps you do too.

Recently, participating in a panel discussion in front of a room full of physics educators, I made the simple statement that “surplus energy grows babies.” This is motivated by my recognition that population growth bent upwards when widespread use of coal ushered in the Industrial Revolution and bent again when fossil fuels entered global agriculture in a big way during the Green Revolution. These are really just facets of the broader Fossil Fuel Revolution. I was challenged by a member of the audience with the glaringly obvious statement that population growth rates subside in energy-rich nations—the so-called demographic transition. How do these sentiments square against one another?

So in the spirit of looking at the numbers, let’s explore in particular various connections between population and energy. In the process I will expose the United States, rather than Africa, for instance, as the real problem when it comes to population growth.

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Man Bites EV: Will EV Bite Back?

electric_car

Electric Car: They Might Be Giants

Some time ago, the Chevy Volt attracted my attention. I think the plug-in hybrid concept hits the sweet spot for American drivers, and the Volt’s 35–40 mile electric-only range seemed to be the perfect number. A pure electric vehicle (EV) would not permit my wife’s periodic work-related jaunt to Pasadena, so any battery-powered solution for us must be of the plug-in hybrid electric vehicle (PHEV) variety. The problem, ultimately, was the high price tag (and the hump in the middle of the back seat occupied by the battery). Although I don’t self-identify as being in the “upper class,” our income edges us into the top quintile in the U.S. So for us to decide that the Volt costs too much—despite genuine enthusiasm—seemed to spell trouble (indeed, the average income of Volt owners was claimed to be $175,000). My conclusion was that electric/plug-in cars are out of reach, and could well remain so.

In April of this year, I became aware of the Ford plug-in, called the C-Max Energi (yes, with an “i” at the end!). The C-Max Energi has a 21 mile electric-only range, and gets an EPA rating of 43 miles per gallon (2.3 gal/100 mi; or 5.4 L/100 km). The price tag is approximately $6k cheaper than the Volt, and the back seat passed my wife’s approval. Nonetheless, after carefully considering the C-Max Energi as a replacement for our increasingly ailing car, we decided against springing for one: still too expensive. I was all set to write a Do the Math post to the tune of “Almost bit on a PHEV again.”

But the fact remained that our 11-year old 28 MPG car (bought used) has been costing us a fair bit in maintenance, its reliability increasingly dubious. Replacement loomed. Motivated by an upcoming long-haul road trip, we explored options again, looking at hybrids and the C-Max Energi. In the end—aided by a federal tax credit, a California rebate, and an unfathomably good offer that together knocked $9k off the MSRP—we drove an Energi off the lot under battery power.

It turns out that:

  • the lifetime cost for the PHEV is still higher than other options we considered, but not prohibitively so given credits, rebates, and discounts;
  • the CO2 emissions are cut in half in electric mode (considering upstream electricity production in our region);
  • batteries still stink compared to liquid fuel, and likely always will.

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Elusive Entropy

partial mixWe’ve all heard it. We think we understand it: entropy is a measure of disorder. Combined with the Second Law of Thermodynamics—that the total entropy of a closed system may never decrease—it seems we have a profound statement that the Universe is destined to become less ordered.

The consequences are unsettling. Sure, the application of energy can reverse entropy locally, but if our society enters an energy-scarce regime, how can we maintain order? It makes intuitive sense: an energy-neglected infrastructure will rust and crumble. And the Second Law stands as a sentinel, unsympathetic to deniers of this fact.

A narrative has developed around this theme that we take in low entropy energy and emit a high entropy wake of waste. That life displays marvelous order—permitted by continuous feeding of this low entropy energy—while death and decay represent higher entropy end states. That we extract low entropy concentrations of materials (ores) from the ground, then disperse the contents around the world in a higher entropy arrangement. The Second Law warns that there is no going back: at least not without substantial infusion of energy.

But wait just a minute! The preceding paragraph is mostly wrong! An unfortunate conflation of the concepts of entropy and disorder has resulted in widespread misunderstanding of what thermodynamic entropy actually means. And if you want to invoke the gravitas of the Second Law of Thermodynamics, you’d better make darned sure you’re talking about thermodynamic entropy—whose connection to order is not as strong as you might be led to believe. Entropy can be quantified, in Joules per Kelvin. Let’s build from there.

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Let’s Blow this Joint

I have a confession to make. When we moved into our current house three years ago, we had to sell our clothes dryer due to gas/electric incompatibility (happens every time we move!). So we lived without a dryer for three years, hanging clothes out to dry, and generally being frugal about washing vs. re-wearing clothes. Well, after several weather-induced trips to the laundromat this winter, we (or can I lay this all at my wife’s feet?) finally broke down and bought a used washer/dryer set on Craigslist. We’ll still let the sun dry our clothes 95% of the time, but have other options now.

Even though this little vignette does relate to the common Do the Math theme of low-energy lifestyles, the actual point of bringing it up is that the washer/dryer came from a house that had just been on display as a model for energy efficiency—including the washer and dryer. At the house, we met Jason Beckman, of Classic Residential, Inc., who had carried out many of the efficiency upgrades to the house. I thought it would be instructive to have him perform an energy audit at our home—especially a blower door test to expose ventilation issues.

As a bonus, after the nominal audit activities were over, I was able to spend some quality time with the blower door, doing extensive tests in virtually every room in the house. What I found was certainly instructive for me, and hopefully will be useful to a broad audience as well.

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Death of a Battery

Four 150 A-h 12-V golf-cart batteries

Four golf-cart batteries used in my off-grid home PV system. Each is 12 V, 150 A-h, thus 1.8 kWh of storage.

All the metrics looked great. The 2.7-year-old lead acid batteries in my off-grid photovoltaic system appeared to have settled into a consistent mid-life performance. Monthly maintenance (equalizing, adding distilled water) promised to keep the batteries in prime condition for some time to come. Based on cycle depth, I expected another 2.5 years out of the present set of batteries. Life was good.

Then, during my absence over the course of Thanksgiving weekend, one of the batteries expired. No forewarning. Just gave up. A previous post expressed an overall disappointment in batteries, now reinforced by this sudden nosedive.

In this post, I’ll show the metrics on my system detailing the demise of “Battery E.” The gruesome graphics are intended for mature audiences.

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