Fly with bird wings on the moon at the Icarus Theme Park

It is said that if people were to fly like birds, our wings would need to be at least *6.7m wide (about 2ft). People also talk about strapping on wings and flying like a bird on Saturn's moon Titan; because the gravity is very weak, and the atmosphere is 50% thicker than on Earth.

Titan is pretty far - but I think this experience should be possible on Earth's moon, where there is 1/6th earths gravity; and if you build a nice dome then you could pressurize the air to earths pressure. I can't say for sure - but I think (with enough effort) human-powered short flights should be possible; or at least wing assisted giant leaps will be possible! (Kind of what chickens do).

            Photo by GerhardLipold form PxHere

One limitation is arm muscles which are a bit weak compared to our leg muscles. For example the human powered helicopter AeroVelo Atlas and Aeroplane Gossamer Eagle both used leg power. For thrust we might might benefit from using giant fins like with freediving in water, but bigger. And then wings would be for lift and control.

Photo by Jean-Marc Kuffer

I imagine a giant domed play area with trees you could fly up to and "roost" on, then glide down. In an environment where exercise is crucial for maintaining muscle mass - this could be a super fun way to go about it. A dream.

While we're at it - some other sports that could be super fun on the moon - freestyle diving into a deep ball pit, where you kind of fall in slow motion and have lots of time to do cool spinny tricks. Also - trampoline jumping where you can go crazy high, comparatively limited risk to breaking your neck. Basket ball could be fun - dunking on impossibly high baskets, though I imagine that dribbling would get annoying fast.

via GIPHY

*These people are Payal Marathe, who wrote this in Yale Scientific and everyone quoting her, I haven't found any other source.
https://www.yalescientific.org/2013/03/qa-why-cant-humans-fly/

Moderate Traffic

Google is truly amazing. Their apps give you the ability to moderate traffic in your area and access to traffic settings with the tap of a finger!

Magentic Field

I am still here

Long time blog readers may recall that 6 years ago I was on Google Street View. Since then, they collected new imagery and my place in history was lost. Well, thanks to a new Google Maps feature, I'm back!

View On Google Maps

Tropicana Orange Juice Doesn't Rot

Some of you may recall the myth of the non-rotting McDonald's hamburger. Fortunately, this myth has been thoroughly debunked. But, I have been doing my own experiment:

We bought this carton of orange juice over 2.5 years ago, and the "best before" date is December 19, 2011. For the majority of the 2.5 years, this carton was held, unopened, at room temperature; it was hidden in the back of our spare fridge in the basement. Yet, there is no external signs that it was spoiled -- the carton isn't bulging or swollen. It just looks like a regular orange juice carton (well, except for the warning label):

So, I decided to open it and see what it looked and smelled like. This is what the juice looked like:

The only obvious change was that it was definitely oxidized -- it had a brown color instead of orange -- and some OJ sediment settled to the bottom, but there was no visible signs of mold or spoilage at all. It smelled like "fresh" orange juice. I was very tempted to taste it, but Stacy wisely convinced me that it wasn't worth it.

There has been a lot of coverage recently about the industrial methods used to make "fresh squeezed" orange juice. See here or here or here. But I think this total lack of spoilage of an allegedly-agricultural product held at room temperature for years speaks both to the amazingness of pasteurization, and to the extent of the marketing fib that is this:

The 1929 market chart is not scary!

The Wall Street Journal's MarketWatch blog recently posted an idiotic chart comparing the behaviour of the Dow Jones Industrial Average in the months leading up to the stock market crash of 1929:

I want to preface the rest of my comments by the following disclaimer: I am not a financial professional -- I leave all serious finance stuff to my talented MBA wife. My approach to economic issues can be summed up by this XKCD comic:

With that out of the way, let's continue. Aside from the fact that the Dow Jones Industrial Average is stupid, there are lots of people commenting on the two-scale axes thing. See here or here, for example. Their basic complaints are that it's not fair to compare the two sets of data because they are scaled to overlay. This is what they look like on the same scale. The red portion is the scary part leading up to the crash:

A little more clarity can be seen graphing these on a log scale:

In any case, this is where my lack of economic knowledge comes in -- I have no idea if that's a good argument or not. But, the graph is still nonsense. First of all, that graph is especially bad, since they didn't scale things correctly and also left out the range of dates used for the 1928-29 dataset. I've done my best to replicate and correct it:

Here, the past and current DJIA values are scaled to fit in the same window. As you can see, there is quite a lot of overlay between the pre-crash data and current data... so perhaps it is scary?

Second of all, and more importantly, I suspected that there were lots of times when the market looks like it does now. So, I wrote a program to go through every 84 week hunk of Dow data and compare it to the current period. This is a graph of the norm of the difference between past periods and the current period:

As you can see, there are many times where the difference drops and there is a time where the Dow's behavior is similar to the current one. In fact, the time with the closest overlap began March 16, 1954:

In other words, this point:

In other words, EVERYONE PANIC!!!   Oh... wait... maybe not. The thing is, people see patterns everywhere, even when they don't exist. To show you what I mean, I made this video:

There's a LOT of self-similarity in the Dow Jones Industrial Index, so it's not surprising that some arbitrary hunk of time-series data looks like another arbitrary hunk. But there is nothing "eerie" or scary about it.

Out of date playground equipment

I saw this at a playground in Teaneck:

I think they should replace this panel with up-to-date IAU planet classifications.

I am quoted in today's Wall Street Journal

Today's front page of the Wall Street Journal contains a story about how Chanukah and Thanksgiving coincide this year. The reporter for that story contacted me because he read my blog post on the topic from December 2010. I was one of the "researchers," and I got a quote in the paper, too!

Also, just so everyone knows, this is not the last time for many thousands of years before Chanukah coincides with Thanksgiving.  As I pointed out in that previous post, in the years 2070 and 2165 after finishing (or in the middle of) Thanksgiving dinner people will light the first Chanukah candle. Additionally, although the first day of Chanukah won't coincide with Thanksgiving until the year 79043, (assuming the calendar isn't fixed before Passover happens in the summer in the year 15115), in the year 76334 the eighth day of Chanukah coincides with Thanksgiving.

Citi Bike is failing at physics

It seems that New York City needs to take some remedial STEM – the promotional materials for NYC BikeShare have an elementary physics mistake.

Their marketing materials state:

[the bike] has a low center of gravity for a more stable ride.

It turns out that a moving bicycle, is actually less stable when the center of gravity is low. Much like a balancing a pencil (low CG) is harder than balancing a broomstick (high CG). This phenomenon is explained well in this article about robot bicycles.

I emailed citi bike to complain and they responded with this:

I'm fairly certain that the engineers involved in constructing these bikes have looked at the pros and cons of both high and low centers of gravity, and found this to be the best option for the widest range of people.

I cannot argue with this. I've ridden these things in Boston and in Washington DC and they are indeed very stable; nicely done engineers! The stability has absolutely nothing to do with a "low center of gravity." In fact the stability to ride might actually be due to a high center of gravity for bike+person compared to more aggressive bike frames.
The next thing citibike said was:

Besides, almost anything with a lower center of gravity is going to be more stable based on simple physical laws.

Correct and irreverent again. Objects siting motionless on the ground will be more stable with a low center of gravity. But bikes mid "ride" are more like an inverted pendulum than a stable object. Here are some suggestions for a new description.

I wouldn't normally be so fast to recommend remedial classes ... but just last march NYC made a subway poster which mathematically embarrassing at best. Also, several years ago Eli previously discussed the state of science education in NYC which left much to be desired.

I'll end this post with a snobby message from Boston: get it together New York!

Shotgun Bulb

Last week I went to visit my old high school auto shop. They where mounting an electronically (or handcuff key) locked shotgun mount. For some idiotic reason this mount which was designed for cars was also designed to take 5 volt DC power (cars use 12 volt DC). To reduce the voltage across the solenoid in the mount they had mounted a resistor in series with the mount, however after they did this the solenoid no longer actuated. I thought to check the resistance on the solenoid and found it to be about 4.5 Ohms, the resistor they were using was a 1 kOhm resistor. What this meant was that there was almost no voltage or current across the solenoid. I did some math and determined that what they needed was a 10 Ohm resistor to get 5 Volts across the mount. However 10 Ohm resistors tend to be far more pricey and bulky than regular resistors because they tend to have to deal with far more power than most resistors due to V=IR (so if the resistance gets smaller and the voltage stays constant much more current is drawn), also we didn't have one. What we did have was an old tail light with resistance close enough for our purpose. So now whenever the switch is flipped to open the shotgun mount a light will turn on.

 The switch.

 The lightbulb on.

 Shotgun mount closed.

Mount open, it is designed so that you can simply flick the switch and pull the gun out.

If you ever wondered what was in a cops trunk. The red and blue lights flash whenever the trunk is open.

Too many emails

Our synagogue, Congregation Shaare Tefillah, has an email list for members. I've noticed an increase in the number of emails I've been getting over the last few months, so I decided to see how bad it is. I've discovered that the number of emails going out has been increasing exponentially. That means that not only are the numbers of emails going out increasing with time, but the rate of increase is increasing with time, too:

The number of emails going out is doubling just over every four years. In seven years we'll have 200 emails a month (or 6-7 a day). It is worth noting that the month-to-month variation in number of emails is increasing, so even if it looks like "Hey, we had fewer emails in month x", it's entirely likely that the next month will be higher:

I recognize that some of this is due to our rapid growth as a shul. However, our emails per member ratio has also been increasing:

The two curves correspond to an exponential fit to both members and emails (the better fit, IMO) and a linear fit. In both cases the number of emails sent increases at a larger rate than the membership.

I'm sure there's something that can be done about it, but, for now, I just set up an email filter...

DIY Immersion Circulator -- Version 2

I decided to upgrade my previous method of cooking sous vide. As I noted in that post, the original version left much to be desired in terms of safety and reliability. Although I originally intended to pack all the electronics into a PC power supply case, as a test of concept I used a plastic storage container:

With this arrangement I had a lot of space to fit everything. You'll also note the outlet on the front. This outlet is controlled by the PID-SSR combo, and leaves me a lot of flexibility for heating elements. Basically, instead of hard-wiring the heaters to the SSR, I wired them with a plug on the end, and it just plugs into the outlet. This leaves me the option of using the controller to regulate the temperature of other devices, like my smoker.
Now, the formerly-packed case just has the heaters and thermocouple attached:

This version also has a cooling fan for the SSR (I cut slots in the side of the container for airflow).

Thus far, I'm much happier with this version. After I've tested it for a bit and am sure that I really like this arrangement, I'm going to try and jam all the stuff into a PC power supply case so it takes up less space. Stay tuned for future updates.

Don't Become a Statistic

The MTA is running a series of ads in NYC subways:

They have newer ones with "preliminary 2012 data," but I don't have a picture of it. I honestly don't understand this "Don't Become a Statistic" to mean "Don't do something stupid that might get you killed" business, because all 1,640,434,526 other people who were not hit by a train are all also a statistic, yet there are no signs up about that! After all, only 0.0000089% of the subway ridership was hit by a train. So, don't feel bad, all 99.9999911% of you who successfully managed not to be smacked by a subway train -- you're a statistic too! Maybe the signs should read:

DIY Immersion Circulator -- Version 1

I decided to upgrade my previous method of cooking sous vide. When I saw these plans for a DIY immersion circulator I was sold. After an Amazon shopping spree, I started assembling the stuff. I borrowed a Dremel (thanks Josh!) to cut the acrylic for the casing and did a dry fit before I started gluing anything:

I then glued in the heating elements and wired the thing up. It works!

Note the eggs in the bath below, at the ideal "soft-cooked" temperature. Thus far I've successfully made soft-cooked eggs and really good white meat chicken in this thing.

But, you'll notice a few things (serves me right for not applying enough critical thinking when reading the plans). First of all, there are wires hanging out the back. There's also a heat sink (metal fanlike structure) hanging out on top, attached to the SSR. The reason is because there's not enough space in the box to fit everything. Oops.

Furthermore, the way the heating elements are set up, I need to fill the bin way up with water or the elements will not be submerged and burn out. And, that's 120V stuff, exposed, directly above water. This isn't a good idea.

So, my plans for Version 2 of this is to put the control portion of the device in a separate container and run the heating coils and temperature probe separately. I'm going with the case from an old PC power supply (cooling fan included, for the SSR). Stay tuned for future updates.

Shabbat on Chanuka

Phil Chernofsky pointed out in a comment on my Thanksgiving on Chanuka post that the civil year 1948 had no Shabbat (Saturday) on Chanuka. This surprised me, as Chanuka is 8 days long, so it must cross a Saturday at some point. However, looking at that year's calendar, it was true! January 1, 1949 was a Saturday on in the middle of the holiday, and the previous Chanuka happened entirely in 1947.  Phil commented that this occurrence is "more than rare; it seems to have only happened for that year."

I wondered if this was true, so, once again, I whipped together a quick Mathematica notebook to look into it (you can download it here). Once again, if you want to skip to the results, you can skip this whole description:

First of all, I use a day-of-the-week function, dow, from this answer on the Mathematica StackExchange site. I first calculate all the days of Chanuka in a given Jewish year:

chanukah[jewyear_]:=Table[DaysPlus[CalendarChange[{jewyear,9,25},Jewish,Gregorian],n],{n,0,7}]

Then, I run this over years starting from approximately when Chanuka historically occurred

chanukahs = chanukah/@Range[3961,5773];

Then, I find which days of the week these dates are:

cdow={#,dow@#}&/@Flatten[chanukahs,1]

Then, I gather all these dates in groups by the secular year:

cdowy = GatherBy[cdow, #[[1, 1]] &]

Finally, I select any year that doesn't have a Saturday in this list of days that Chanuka occurred on:

Select[GatherBy[cdow, #[[1, 1]] &], Length@Select[#[[All, 2]], # == Saturday &] == 0 &]

Sure enough, 1948 was the only civil year since the beginning of Chanuka till now that did not have a Saturday on Chanuka! So, it seems Phil was right.

But wait, there's more. What happens in the fuuuuuutuuuuuure?

We're currently at the dashed horizontal line. The next occurrence is in 2043 followed by 2100. The reason we haven't had any until now is because the Jewish calendar drifts around 4.3 days later every 1000 years, and originally the calendars were sufficiently separated that it was a rare event. Moving forward, however, it turns out, that it's actually a fairly common occurrence to have a civil year without a Shabbat Chanuka!

So, while 1948 was the first,  it's far from the only time there will be a civil year without a Shabbat Chanuka. And, eventually, in a few thousand years, the Jewish calendar will drift far-enough past January 1st that it will become a rare occurrence, yet again.

Thanksgiving Reminder

This is just a reminder that next year is only one of 6 predictable times (8, if you're a Republican) Chanuka will ever fall out on Thanksgiving. See my analysis from two years ago. I also underestimated Steve Morse's tool. He recently contacted me and informed me that he did account for the change in Thanksgiving's date (serves me right for not looking at his site's source code). However, he did not consider the Republican Thanksgivings. He has also recently updated his site with some analysis on this issue, see here: http://stevemorse.org/jcal/chanukah.html

And, my original analysis is still up here: http://eli.lansey.net/antics/ThanksgivingsWeb.nb If you don't have Mathematica, if you want to read that file, you can install Wolfram's free CDF player and browser plugin, available here: http://www.wolfram.com/cdf-player/

Solar Sillyness

In recent years PSE&G the main local power company has been installing solar panels on utility poles.  Many have long considered this to be a complete folly.  Well I am here to both prove them correct and show an inaccuracy on the PSE&G website about these panels.

During Hurricane Sandy a number of utility poles came down in my opinion largely due to the large sail like solar panel bolted to them.  All my simple analysis will exclude damage caused by solar panels and maintenance costs.

Hurricane Sandy is was caused me to start thinking about this.  I looked on the back of one of the downed panels and found out how much power they are rated for.  The panel was rated for a maximum of 200 watts (AC).  A MAXIMUM of 200 watts!  It also must be pointed out that this is when the solar panels are at 45 degrees Celsius (113 degrees Fahrenheit).  I will also assume that the price of this unit is about $650 as this seems to be the approximate price of a good solar panel in this wattage range.  Given all the things stacked against the solar panels like our climate, clouds, winter, and trees, I will assume (very generously in my opinion) that they generate about 50 watts for about 8 hours a day on average over the course of the year.  The manufacturer of these panels Petra Solar gives a data sheet for these panels and the dimensions are given as 66.14" x 39.40" or about 5.5 ft by 3.3 ft.  They also confirm the output of 200 watts, however the PSE&G website claims they put out 235 watts (DC), they do however have a 240 watt (DC) max INPUT.  This may just be do to me not understanding what they are talking about, but I rather suspect they like having a higher number on the site.  It will also be noted that Petra Solar give a limited 5 year warranty.  I will assume the panel has a 10 year lifespan (which is also very generous).

Its time to do some simple math (50 watts)*(8 Hours)*(1 kW/1000 W) = 0.4 kWh, so each day on average one panel generates 0.4 kilowatt hours (The average American household uses about 31.5 kWh a day).  So (0.4 kWh)*(365 days/year)(10 years) = 1460 kWh, which means that over the course of 10 years that panel will power one house for about 46 days (this is of course assuming that the electrical usage of the average American stays the same for 10 years, which is a very silly thing to assume).  Lets now calculate the cost of the power coming from that panel. ($650/1460 kWh) = $0.4452/kWh or 44.52 cents/kWh.  PSE&G rates(page 51) are 16.57 cents/kWh (NJ has on average the 4th most expensive electricity in the country).  This means that over the course of its lifetime the solar panel is 2.69 times more expensive than the normal grid power cost, in fact it would take 26.87 years for the solar panels to break even at current rates.

The final analysis shows very clearly that theses panels are totally stupid, and a huge waste of money.  These costs don't include the cost of instillation which with unions could increase the initial cost by 50%.  Additionally, this doesn't take into account damage they cause due to storms which can exceed the simple cost of replacing the pole due to property damage and people being out of power.  So basically they exist because uneducated people who can't do simple math think they are a great idea.  Oh also the government gave huge tax breaks for putting in these humongous wastes of money.

Mathematica StackExchange Swag

I've been a member of the mathematica.stackexchange.com Mathematica Q&A site since it started (I'm user #9). The site recently "graduated" from beta, and they gave away some "swag" to top users. Although I haven't been that active recently, I was early on, which placed me in the top 14% of all-time users, and qualified me for some swag.

So, a few days ago, I got a box from StackExchange:

How awesome is it that StackExchange's address is on Exchange Plaza?!?

Anyway, inside was a T-Shirt:

and some assorted stickers and writing implements:

Forget any academic credentials -- this is some exciting nerd cred!

Welding

Prepare to be amazed by a blast from the past.  I took a welding class about 3-4 years ago.  That's right this blog post has literally been years in the making!  The class was offered by a local vocational school and was geared as adult continued education.  I learned arc weld, MIG weld, brazing, and how to cut steel with an oxyacetylene torch.

 This was my basic welding setup.  I had an auto-darkening helmet, this meant that when I struck an arc the goggles immediately darkened so I wasn't blinded, but when I wasn't welding I would be able to see what I was doing.  Additionally, I am wearing a welding coat, its treated cotton.  Also, thick leather gloves.  On the right is a wire brush for cleaning up welds and on the left is a welding hammer, its to clear off slag.

This is my brazing and oxyacetylene cutting getup.  Same shirt and and gloves but wearing brazing goggles.  On the theme of a long time coming, I was clearly way ahead of the times.  Watch out guys, we're dealing with a badass over here.

HELP!!!

Four years ago I committed a single act of graffiti in the Rutgers Engineering building.  In pencil I wrote a message on the top of a display case.

As is clear from this picture it is still there.  For those of you who need glasses.

Help I am Stuck in A Display Case.

The thing I find surprising is that no one has let the poor guy out of the display case.  Also, if he was inside the case how did he write on the outside, I guess only those of you who read this will know.