Gravity & Energy

This category of the blog is dedicated to science & technology topics that I think may interest my fellow nerds.

(Note: Original post: 2012. A few updates were made during site reorganization in January, 2021.)

Tracking Movement In the Solar System

For starters, I’ll be posting in the blog regularly under Astronomy & Astrophysics. (In some of these older posts the category is tagged Pixel Gravity.)  To jump straight to those posts, visit the PG Archive–readily accessible in the menu.  For some time now, I’ve been running the social-media support for the program that made the picture you see here.  I’ve been posting about robots, space exploration, astronomy, big steps in physics, and so on.  Sometimes, the space available for a posting on Facebook is too restrictive.   So those kinds of discussions will move here.

What qualifies me to write about this stuff?  Well, I’ve admitted elsewhere that we are a family of hypernerds.  That’s not my term.  It was invented and applied by one of our charming (adult) offspring.  It’s not a misnomer As a family, we are 40% engineers and 60% scientists.

I’m a power systems engineer, which in my case means I’ve made a career out of simulating how power plants and electric and gas networks operate.

My husband is a computational physicist, specializing in solar physics.  Want to know what’s going on inside the sun?  He’s your guy.

Our youngest son is too busy for now, building catapults and robots on his way to a mechanical-engineering degree at UC Santa Barbara. (Update: graduated, with honors. Currently open to job offers.)

After two summer internships in NASA’s astrobiology group, our middle son is working on an honors thesis project on metabolic processes of microbes in deep serpentine wells, attracted by the prospect of doing biology fieldwork in extreme ecosystems right here on planet Earth. (Update: he’s now nearly done with his Ph.D.)

And the oldest escaped from UC Berkeley’s astrophysics program with a degree and a desire to never return to academia.  He built Pixel Gravity instead.

What’s “Pixel Gravity“?  It’s a detailed, graphical astrophysics simulator with real-time controls.  It looks sort of like a game, and it’s fun to play with, but it’s also a serious science tool  As an “n‑body” simulator, it lets users model complex groups of many objects, from the solar system to galaxies.  Most of the other easy-to-use programs available online limit the number of objects or lack physical accuracy, so (for example) relativistic effects on motion near a black hole are not handled properly, if at all.  University researchers have access to extremely-detailed models, but those require supercomputers.  Pixel Gravity provides accurate modeling on personal computers and is priced low so that even students can explore gravity in action.  In addition to Newtonian gravity, Pixel Gravity models the additional effects of atmospheric drag, general relativity, and dark-matter, as well as user-defined forces.  Plus, the software package includes helpful tools for curriculum development such as a tutorial-builder and video-production capability. (Update: Pixel Gravity is at present a retired product–contact us if you’d like a copy to play with.)

So, in short, the topics under this heading are just the kind of things we talk about at our house.  So if you come to dinner, you don’t need to bring a foodie specialty.  But you might scan the latest issue of Scientific American.

You might also like to read:

Walking to Pluto: Step 1Walking to Pluto: Step 1

 

Compare the sizes of Earth and Pluto & Charon Image Credit: NASA

Compare the sizes of Earth and Pluto & Charon (Pluto’s shadow isn’t that big on Earth!) Image Credit: NASA

It’s been a super-fantastic #PlutoFlyby day (see the video for a Pixel Gravity simulation of New Horizons’ close approach path on 7/15/2015), and I can’t resist going to one of my favorite astronomy projects:  building a scale model of the Solar System that takes you out of the house, out of the classroom, and under the sky.  (Where maybe Pluto’s shadow, cast by a distant star, will pass over you.)

As a reminder, you can look for the following in any Messy Monday project:

  1. A set of notes for project leaders, sketching the key elements of the project and the science topic it is meant to address
  2. A detailed supply list, structured to make it simple to purchase supplies for either a one-shot demonstration or for a classroom-sized group activity.
  3. A set of instructions for working through the project with students, including commentary to help cope with common classroom-management issues, questions that are likely to arise, and issues to keep in mind from safety to fairness.
  4. A rough estimate of the cost to run the project.

 

As before, I’ll break down the presentation into four postings, to spare readers trying to scroll through a 5000-word document, but I’ll post them quickly, so you can jump ahead if you are raring to go or want to access the reference materials first.  In other projects, we built our own comets. In this project, we travel out into the solar system, hoping to reach the source of that comet.

 

Step 1: Space is Big

It’s a long way to Pluto. But as far as the Universe is concerned, Pluto’s in our condo’s tiny back yard. What would it be like, though, to take a hike to Pluto? Like the New Horizons Spacecraft spacecraft buzzing past Pluto and its cluster of moons, but, well, maybe taking a bit less time about it. Nine years (the explorer was launched in early 2006) is longer than even the above-average student’s attention span. What if we could shrink the Solar System down to a reasonable size for nice walking field trip?

Paths of the nine planetary objects orbiting the Sun for many years.

Paths of the nine planetary objects orbiting the Sun for many years (A Pixel Gravity simulation result.)

No surprise here: it’s been done. Six ways to Sunday, in fact. While no one person claims to own the idea of building a scale model of the solar system, my favorite advocate of such models is Guy Ottewell, who likes a scaling factor that makes the model a reasonable size for the average person to walk. You can buy his book on the subject (now with cartons!) at the books page on his website. As a bonus, you’ll also find the most current editions of all of his other books on astronomy and much more.   (He self-effacingly describes his annual Astronomical Calendar as “widely used”; a more-accurate description would be “fanatically used by serious amateur astronomers”.)  No disclaimer necessary;  we’re not friends, I’m just one of his (many) Twitter followers.

The goal of this project is for everyone involved to obtain a personal sense of the feature of Outer Space that is hardest to conceptualize by reading books and trolling the internet: Space is BIG. (Yes, you may pause to reread the opening to The Hitchhiker’s Guide to the Galaxy, by Douglas Adams.)  Indeed. Really Really Big.

Our neighbor galaxy, Andromeda (Image Credit:  ESA/Hubble)

Our neighbor galaxy, Andromeda (Image Credit: ESA/Hubble)

On top of that, the places you can stop—the non-empty bits—are few and very tiny compared with the distances between them.  And it takes a long time to get from one stop to another.

So, when assembling materials and presenting this project, keep these two key goals in mind. It’s not important whether you model Earth as a peppercorn (Ottewell’s model) or an allspice seed (easier to find in my own kitchen) or a spitwad from the ceiling that happens to be about a tenth of an inch across.   What’s important is that the Earth is not only extremely teensy compared to the Sun, but you can’t even fit the Sun and Earth into an ordinary classroom. And you have to hike at least a half a mile (a kilometer) if you want to make it to Pluto. With any luck, you can make practical use of the excess energy in a classroom-full of kids and also amaze them. If you’re doing this as a classroom helper and the teacher is used to taking advantage of the time to catch up on infinite paperwork, this is a time to persuade that teacher to shove the paperwork aside and join the expedition. There will be no regrets!

The objects used to represent planets and other bodies should be chosen for familiarity, because you want the participants to absorb the scale comparisons effortlessly. “Everyone knows” how big a jellybean is, a pin is familiar—both the pushing end and the painful poking end—a soccer ball is a known object, and so on. It doesn’t matter if the object you use is not exactly the design diameter—and no one is going to care that jellybeans or coffee beans are bumpy ovoids, not spheres. The next time you’re eating a jellybean (or slurping a Starbucks), at the back of your mind will be “I had to hike a half-mile just to get to this little Neptune here”.   Plus, “Yum, astronomy is delicious.”

If you’re interested in the underlying concepts, I encourage you to stop by the National Optical Astronomy Observatory’s website and read Guy Ottewell’s original 1989 description of his Thousand Yard Model; however, if you consider yourself a mathphobe, don’t let the arithmetical computations worry you. I’ve made you an Excel worksheet to do that task. Running a mind-expanding science project should help relieve that condition, not make it worse.

If you have visited a museum’s scale model, read Ottewell’s book, or done a similar project in the past, there are a few differences you may encounter in this project. In particular, I suggest you avoid having planets represented by peanuts. Including nuts in school projects, can be problematical if any student (or parent helper) with nut hyper-allergy could possibly be affected. (I have relatives with this allergy, and there is nothing quite like coping with anaphylactic shock to ruin a day’s outing.)

Dwarf Planet Ceres Image Credit:  NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Dwarf Planet Ceres Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

I’ve included a few more “destinations”—such as the ever-popular asteroid “belt” and my personal favorite of Pluto’s fellow dwarf planets. The number of steps taken between planets (and other destinations) is greater, because kids take shorter steps than grown-ups. (Also, other models I’ve seen assume a stride length more typical of men—and the majority of teachers and parent volunteers are still women, with shorter strides than men.) And I’ve included the current (for now, at least) locations for a few more distant “destinations” that we can look out towards from our turnaround point at Pluto.

The tables I’ve provided are in both English and SI units. The scales are slightly different between the two, in order to yield intuitively-scaled results in either set of units. And I’ve provided a “cheat sheet” of the key data for a teacher or other presenter to carry as a reference source on the walk. If anyone would like to get completely precise and build their own model matching their pace length exactly, or adjusting to a different scale, you can request a copy of my Excel workbook for this project to create your individualized pace-off. Or if you know a Senior Girl Scout or Boy Scout in need of a Gold Star or Eagle project, a community solar system model would be a very cool service project. (C’mon, Scouts, do you really want to build another park bench?)

Speaking of space, and coolness, and peanuts, and bigness, by the time your group finishes this project—everyone who participates should wholeheartedly agree:  Space is Big

A Sign From NASA

A Sign From NASA

 

 

 

Convention Time is a-Coming, Ha-HaConvention Time is a-Coming, Ha-Ha

I’m all kinds of happy about convention time this year. It makes up for a lot of crummy stuff that happened in my little world in the first third of 2018.

BayCon programming liked some of my program ideas.  They even put some of them on the program! Even better, though a little scarier, they plunked me down as a panel member on two of them and asked me to moderate a third.  I’m getting better at this panel thing, though.  I’ve discovered I do have a few things to say, and I have managed to steer a group around to keep the panel on track or at least bring the quietest panelist back into the conversation.  I’m solidly on science track this year, so I will make sure to brush up on my Real Facts before I show up.

Here’s my schedule, just in case anyone’s looking for me.  Or at least so I have a place I can look this stuff up, myself:

What?Who?
Sunday, May 27 at 1 pm
Science and Politics in the USA: Latter Day Lysenkoism?

Can US science recover from the anti-science policies of politicians? Where will the damage be most significant?
Edward Kukla
(educator, biologist, mathematician, a moderator who knows how to make Ph.D.’s behave themselves)
Bradford Lyau, Ph.D.
(historian, political activist, literary analyst)
Vanessa MacLaren-Wray, Ph.D.
(science activist, writer, engineer)
Howard Davidson, Ph.D.
(turns science fiction into real-world stuff)
Sunday, May 27 at 4 pm
Bad Science: Pseudoscience, Hoaxes, and Illogical Thinking

When we’re reading or writing science fiction, we’ve got some poetic license, but we want the science to be fundamentally right.
When looking for science resources, how do we winnow the chaff from the wheat?
As a bonus, really bad science and hoaxers provide excellent fodder for parody SF.
(I’m a big fan of Phil Plait, whose “Bad Astronomy ” column is a good example of this kind of thinking.)
Vanessa MacLaren-Wray, Ph.D.
(writer, mechanical engineer, writer, used to managing a roomful of smart guys)
Howard Davidson, Ph.D.
(physicist, inventor)
Arthur Bozlee
(aerospace entrepeneur, oughta have a Ph.D., should hire the rest of us)
Jim Doty, Ph.D.
(writer, electrical engineer)
Monday, May 28 at 11:30 am
Wild Weather

For the first time, science can show
that three extreme weather events would not have happened without global warming,
including the rain bomb that drowned Houston.
We’re also seeing tropical cyclones cross into the Bering Sea,
and cold snaps bringing snow to the deep south.
What can we expect to happen with tornadoes?
Patricia MacEwen
(writer, physical anthropologist who also uses her knowledge for our kind of stories, all-around awesome person)
Vanessa MacLaren-Wray, Ph.D.
(writer, engineer working on energy efficiency to fight climate change)
Heidi Stauffer, Ph.D.
(real-life educator and environmental geologist, i.e., this stuff is her field exactly)

My BayCon program schedule has some holes in it, so I plan to take some time and scoot down to Fanime that same weekend.  I love the costumes, and I’ve lately acquired a taste for Japanese pop music, and have even watched some of the anime (especially, of course, the science fiction) that rolls through on Netflix.  I have an in-house anime expert who can give me insider tips so I don’t have to watch everything to find what I’ll like.

WorldCon is in San Jose this year!  I am so stoked!  I submitted some program ideas to that group as well, though haven’t had any feedback from them.  Though I don’t expect to actually be on program, if they use any of my ideas I will be sure to go around claiming credit for them.  I’m finally paid up on my membership (thank heavens for installment plans).  My last WorldCon was in Spokane, and that trip was super-fun, but it kind of broke the family bank.  With the con in San Jose, it’s an easy daily commute.  Niiiiice.

Al Gore sitting with Angie Coiro on a stage with a screen behind them and cups on a table in between their chairs. Angie is holding her laptop computer as she listens to Al answer a question.
Climate science advocacy up close and personal. (Al Gore and Angie Coiro, December 7, 2017)

Al Gore won’t be coming to BayCon, but we’ll do our best to cover for him.

Day Zero: Get Thee To FlagstaffDay Zero: Get Thee To Flagstaff

There is no simple way to orchestrate the travel here.  Yes, planes fly to Flagstaff, not the same airlines as fly to the big airports but their small-scale partners.  There’s a shuttle bus from Phoenix, and if you were facing a long layover the van could even be faster.

A view of the Grand Canyon we did not see on our flights (courtesy of Google Earth)

But we arrive in Phoenix with plane tickets in hand and actually welcome a half-hour flight delay, because it allows us a chance to buy lunch.  I even have time for a stroll through the overpriced-souvenir shop, where I hand over $2 for a pair of elastic bands someone in the shop has put out to support a fundraiser for improving water supplies in Haiti.  Seems appropriate. And the chance to put up our feet for a half-hour is welcome, as we’re already tired.  We actually began yesterday, on Day “-1”, with a five-hour drive to rendezvous with Clark’s friend, who lives near Reno, so we could all travel together the whole way.  Our Day Zero expedition consisted of a drive from the pine forests of Plumas County to the desert flats of Reno’s outskirts, a freeway jaunt to the airport (chauffered by another friend), a big plane to Phoenix, a little plane to Flagstaff, then a search for the airport shuttle.  We will have a powerful case of deja vu on Day Fourteen.   You’ll see.

Flagstaff’s airport is a fabulous, small airport.  My favorite kind.  One baggage claim zone.  No trouble meeting a shuttle bus right outside.  As it happens, the other folks sharing the van are another couple going on our trip.  And they have obtained an intelligence report from the rafting company, OARS, that we five will be the only “guests” staying on the raft trip for the full fourteen days.   The rest of the group will leave halfway (and hike out), to be replaced by a new batch of folks for the second week.  So we will actually get to spend a full fifteen days with Todd and Eliza.  Oh, yeah, and until such time as the members of our trip group authorize me to use their names, I will be using fake names, just in case I goof up and say something upsetting or someone turns out to be in Witness Protection.  I won’t do the same for the crew, since I want to actually give them the props they deserve.  In fact, I’d hope this whole piece could be considered a humungous letter of reference for each and every person on the crew.  I’d initially given myself permission to use my own and my husband’s names, but he protested, so here goes.  He is herewith dubbed “Clark”.  And what to call Childhood Friend?  How about Lana?  And surely that makes me “Lois”.  The only funny thing about this, is that I actually have a friend called Lois–so, hey, Lois, you can tell people this is you.  (Fair warning, though, I’m not the heroine of this story!)

The key element of Day Zero is the evening briefing from the Trip Leader.  We gather in one of the Radisson Hotel’s conference rooms.   (The Midway guests also will have a briefing, but not by the Trip Leader , as she will be a mile downhill at the time.)  So we meet our first authentic River Guide.  This is Billie Prosser, who’s been whitewater rafting since she was a teenager, over fifteen years now, much of that time in the Grand Canyon.  These days, she chooses to do only a few of these Grand Canyon trips a year, giving herself the chance to work on other rivers and also to have time for a private trip, as time permits, to enjoy the Canyon without having to take care of people like us.

At the meeting, we also get our first glimpse of our fellow travelers all together.  We are heavily loaded with Californians and Canadians.   There are three women from Canada—their menfolk didn’t want to come.  There’s two father-son duos: one a dad and his athletic teenager, the other a Bechtel project technician taking a voluntary layoff to make the trip with his dad, a (putatively) retired actor and writer.  The Fab Five (Todd & Eliza and the three of us–Lois, Clark, and Lana) are all from California.   The actor, who takes care during the meeting to firmly establish that he’s the most-senior member of the troupe, has also brought along a childhood friend—a woman he hadn’t seen since high school.  While he keeps us entertained, I get the vague feeling he sort of expects someone to recognize him.  Then there’s another triad…a husband and wife and one of their friends.  Is that sixteen?

We get a quick summary of what to expect in the morning.  The crucial item is to have our gear packed and in the lobby by quarter to seven and be ready to leave by seven.  There’s a little last-minute advice on what to be sure to bring.  In case something’s been forgotten, there’s a WalMart in walking distance.  We’re advised to bring lots and lots of moisturizer.  I ask for a definition of “lots”, which it seems is a 16 oz bottle per person per week.  Oh, my goodness, I didn’t bring that much, so we have a trip to WalMart in the plans already.  We’re issued our “drybags”, each labeled with our own personal real names.  (Amazingly, they don’t know to use the fake names I will make up in the future for this blog.)  And Billie gives us a five-minute seminar on how to seal the drybags.  This is important, as all of our clothing and personal items go in this bag, which will then be tied onto a raft and frequently doused with water.  We’re each also issued a small drybag.  The big bag is inaccessible except in camp.  The day bag serves to keep dry what we need to keep dry but have access to during the day.  And we’re allowed to bring whatever we like in our daypacks as well, provided we understand that these will get drenched in larger rapids or if it rains.  The drybags don’t have our personal names on them.  Instead, they each have an identifying name written in Sharpie,  to individualize them.  We just each have to remember our bag’s name.  Mine is “Turpentine Broom”.  Lana’s is “Grease Bush”.  And Clark selects the distinctly memorable “#73”.  Mine is the best.  Here is all about Turpentine Broom  and Grease Bush.  I expect we’ll encounter these plants on our journey.  In the meantime, the names help, as the bags come in only a few colors.

I’m relieved to hear there will be a bag for boots, as this will make room in my kit for all that moisturizer.  Others are relieved to hear that their beer and wine orders have been filled.  Some are anxious to double-check on that after the meeting.  Billie has the checklist.  Evidently, this is a common anxiety.

Then we are off to WalMart.  Yes, our first act upon crossing the moment into our trip environment is to walk down a suburban city street, past a dark and quiet Home Depot, an active supermarket, and a Bank of America with lights glowing invitingly above its ATM, to shop in the megabehemoth of a store that was launched just a few miles from Clark and Lana’s home town.   But oh, they do indeed have It All.  More sunblock.  I must have more sunblock.  Moisturizer, per Billie’s recommendations.  Handy dry facewash cloths to get all that sunblock off.  And a tripod.  What was I thinking, leaving home without a tripod?  And a little mini flex-tripod for Clark.  Sweet.  Now all we have to do is haul this all back to the hotel and get everything crammed into our bags.

And, well, the bag-cramming takes a little while.  Maybe more than a little while.   Part of it is deciding which things are OK in the backpack (maybe in a Ziploc bag, maybe not), which need to go in the daybag, and which can be done without and stuffed in the main drybag.  I have the extra variant that I really have 2 daypacks. One is a one-shoulder sling pack that keeps my cameras and other hiking essentials from bearing down on my healing shoulder and when not in use tucks into the main pocket of my large daypack.  The main daypack takes my raingear, a dry set of fleece sealed in ziplocs, my tripod, and other handy items.  It’s big, it’s bulky, I will make Clark carry it as much as possible.  But it all fits.  And while I fancy myself adept at this sort of thing, it is Clark who is already proving to be better at sealing the big drybag.  He says it is just that he can squish it down better, being a bit heavier, but I think there is more to it than that.  I will keep insisting on doing my bag myself for about four more days.  Then I will give up and let him do it for me.

One last shower and a thorough hair washing.  It will be 2 weeks without a shampooing, at least for me.  I do not want to look at the setting on the alarm clock.  It is just too awful to contemplate.

 

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