Senses and Sensors

"If you had to choose, would you rather be deaf or blind?"  This was a fairly common question that kids asked each other when I was growing up.  I think my answer was "deaf", and I think it still is today.

When we have all of our senses, we often take them for granted, forgetting that there would be absolutely no way to perceive reality without them.  The least important senses in the modern world are probably a tie between smell and taste.  Although, I can imagine a time when these were necessary to correctly judge whether or not something was safe to eat.

I would argue that the single most important sense, however, is touch.  This one is probably taken for granted more than the others, and it actually encompasses so much of our interaction with the world.  Unlike the other four senses, which are local, this sense is global.  We have countless receptors all over our body sending information to our brain.  In particular, these receptors measure temperature and pressure: two critical inputs to safely navigate life.

In truth, sense of touch is not really an appropriate term.  We never actually touch anything.  inter-molecular lattice of which our skin is composed actually becomes more compact, and resists this departure from the equilibrium that preceded it.  It is for this reason that a "push force" is actually an electromagnetic force.  When we press our fingertips against something we cannot see, we judge it to be soft or firm based not on what it does, but rather what it does to us.  A given force per unit area at the contact causes our fingertips to deform slightly (to strain), and our internal pressure sensors inform us about what we are "touching".  When we "touch" other things, weak bonds also form between the atoms on our fingertips and those on the surfaces they are in contact with.  This can actually allow us to pull things too via static friction.

The Future of Speeding Tickets

Radar guns work by way of the Doppler Effect principle.  A signal is sent from the radar gun to the moving vehicle.  The signal reflects off of the vehicle and strikes the radar gun where it originated from.  The radar gun compares the received signal to the one it sent, and then, based on the frequency shift, computes the speed of the moving vehicle.  This very same principle is invoked to determine the relative velocity of distant stars based on the frequency shift of the light they emit.

When I first learned about the Doppler Effect and its application to handing out speeding tickets, I wondered why policeman were always stationary while using it.  After all, the devices measure relative velocity, so if the motion for the radar gun itself were accounted for, it could still compute the absolute speed of moving cars with sufficient accuracy.  For example, a radar gun could be mounted onto a police car, and have the vehicle's speedometer as an input - the device could then fire radio signals to cars behind and in front, receive the echo, compute the relative velocity, and then the absolute speed.  When I mention this to my students, they sometimes respond with, "Don't give the cops any ideas."

Halloween: A Celebration of Fear

Halloween was always one of my favourite days of the year as a child.  Even as an adult, I get a small rush as the last day of October approaches; I even get to relive the experience through the eyes of my own kids - one will be Spider-man, the other a kitten.  I love it all, from the costumes to the pumpkins and candy.  But what fascinates me most about Halloween is the spookiness that goes along with it.

The Q-Ray and Critical Thinking

Advertisements for the "Q-Ray" have me shaking my head again.  You've no doubt seen an ad for the metal bracelet that can improve your life in every conceivable way.  How can these metal bands help its wearer navigate life's obstacles, you ask?  Well, they are positively charged you see, and this charge will seep into the wrist it sits on, and then consume the body of the individual.  A better question might be, "How many illicit drugs were the makers of these 'devices' on when they thought people would be dense enough to believe this nonsense?"

I guess the joke's on me, because the Q-Ray, also known as the second dumbest product after 'Head-on', is back.  So profitable are these magic bracelets that they are again being sold, even after suffering a verdict that should have spelled the end of Q-Ray.  As reported by Consumer Affairs, "In November 2006, the court required the defendants to turn over a minimum of $22.5 million in net profits and up to $87 million in refunds to consumers who bought the bracelets between January 1, 2000 and June 30, 2003, when the bracelet was advertised on infomercials and Internet Web sites, and at trade shows."

According to the ruling at that time, Q-Ray was misleading consumers into believing that the bracelets actually did something.  Apparently, this multi-million-dollar slap on the wrist was not sufficient to deter the makers of Q-Ray (they must have been wearing a Q-Ray bracelet at the time the decision was handed down - apparently, Q-Rays heighten one's persistence).

Montreal's Revamped Planetarium Worth a Visit

Just because your dad teaches physics and writes science articles as a hobby doesn't necessarily mean that he will take you on a field trip to a planetarium - but it certainly does increase the odds.  I took my four-year-old to Montreal's relocated Planetarium this past weekend and would recommend it to others.

Chief Technical Editor of Climb

When I look at other fellow engineers, there is one trait that we tend to share besides the obvious ones (affinity for Star Wars, unwarranted big egos, etc): lots of extra-curricular activities.  Most engineers that I know play in a sports league and are involved in multiple projects outside of their actual profession.

I play on a soccer team, drum in bands from time to time, and manage this blog.  Well, I now do something else - this week I was asked to be the new Chief Technical Editor of Climb, the Space Elevator Journal affiliated with ISEC (the International Space Elevator Consortium).

Cover shot of Climb, Vol. 1 (courtesy of lulu.com)

Orienteering is all About Finding Your Way

As a thirty-one-year old, it is refreshing to do something for the first time.  Such was the case last weekend when I went orienteering with my family at a large green space near my home.

For the uninitiated, orienteering is a sport whereby individuals or teams locate 'x' number of checkpoints in a specific order in an open space in as little time as possible equipped with only a map and a compass.

Groups of people of all levels of experience showed up last week: there were four levels of maps and corresponding checkpoints ranging from 'first-timers' to 'advanced'.  Much like the 'spice level' I that I tend to select at an Indian restaurant, we chose level 1.  It was easy to identify the level 4 orienteers - they were the ones popping in and out of thick forest as though the trees and bushes were not there (they were also the ones sweating).

If you want to be a bad-ass orienteer, you need a bad-ass hat

Homogeneity is Overrated: the PQ can Keep Their Charter

I am so sick and tired of the elected leaders of this province I live in called Quebec.  Today, the leaders of the Parti Quebecois (PQ) have put forth a Charter of Secularism which, among other things, forbids public servants from wearing religious garb while performing their duties.  As an educator at the college level, I am a public servant, and though I almost never wear a kippa in my day to day life, I don't see what business it is of this provincial government if I should decide to do so one day.

The minister in charge of what I would call the charter of division, Bernard Drainville, defends the proposed changes to civil servant dress code as follows: "If the state is neutral, those working for the state should be equally neutral in their image."

When one sports a religious symbol, one's capacity to perform one's duties is undiminished.  If the population is so offended by workers wearing such symbols, then what they need is a lesson in tolerance; they do not need legislation that reinforces such xenophobia.

When I look at the richness of the matter that is around us, I see heterogeneity.  I see hundreds of different kinds of atoms that intermingle in countless ways, forming compounds, each exhibiting unique properties.  The diversity of matter can serve as a model for society.  It saddens me that Pauline Marois, Quebec's Premier, sees multiculturalism as a threat to her Quebecois ether.

I want to live in a society where one's belief system is outside state jurisdiction.  Those behind this charter would likely deem it to be progressive, but it is clearly regressive.  It's aim is unmistakable: to make those whose heritage is not Quebec feel unwelcome.

I could rant on and on about this, but I need to prepare a lecture on mixtures.  As a civil servant, I will fulfill my duty, and focus only on homogeneous ones.

The Wright Brothers Stood on Cayley's Shoulders

Sir Isaac Newton famously expressed that in order to make his numerous contributions to science, he stood on the shoulders of giants.  This seems to be a modest claim given the huge individual leaps of intellect he made.  A book that I recently read, "The Man who Discovered Flight: George Cayley and the First Airplane," by Richard Dee, had me thinking about the notion of how we are always continuing the work of our predecessors.

When any of us think about the first airplane, we invariably think of the Wright Brothers and their historic achievement; few have ever even heard of George Cayley.  Cayley's contributions to aviation were numerous, but they preceded the Wright Brothers' flight by about a century.  Consider this excerpt from Dee's book:

"Within the course of six scribbled pages in his notebook, Cayley had shown that man-made flight by wing was a theoretical possibility, but practically, with engineering constraints as they were at the time, it was a non-starter.  So having discovered that it could happen and then almost immediately proving that it couldn't happen yet, what next?"

Elon Musk's Hyperloop is Bold and Ambitious

Perhaps you've heard of the recently proposed revolutionary transportation system dubbed the Hyperloop.  No?  Google it.  The vast majority of posts on the topic that I have read go beyond mere skepticism and describe the project as just short of impossible.  What is it about dreamers that brings out the haters?

The Hyperloop was described by its inventor, Elon Musk, as "a cross between a Concord, a rail gun and an air hockey table."  Picture those hollow tubes that shuttle documents through offices by way of air pressure (in movies - I've never actually seen one in real life, but I assume they exist).  Now enlarge the diameter of the tube, replace the tiny capsules with pods containing passengers, and have the ends connect two distant cities, and you begin to grasp Musk's intriguing mass-transit system.

The initial proposal calls for a train that links Los Angeles and San Francisco - the specs call for a thirty-five minute shuttle time each way.  The distance between the two cities is about 600 km.  Is this beginning to sound like a high-school mechanics problem?  Let's spice it up a bit and stipulate a 0.2 g acceleration from rest to cruise and 0.2 g deceleration from cruise to rest.  Try to calculate the cruise speed...