Monday, October 22, 2018

Interstellar Missions a 21st Century Possibility

I was at the 2nd Montreal Space Symposium this past Friday, held this year at Concordia University.  I could only attend one of the days, and was again impressed by the level of professionalism the student-organized two-day conference was run with.  I appreciated the format this year, where more than 50 talks (mostly around 15 minutes with 5 minutes of questions) were run, usually two concurrently.

The one talk I took in at the conference that I will never forget was given by Professor Andrew Higgins (Mechanical Engineering Department of McGill University).  He and I have not crossed paths much since the last time I was a student in one of his courses (Fluids II in 2003, I believe).  The talk, entitled, "Bringing Interstellar Down to Earth," was delivered with his usual sense of humour and flair for the dramatic.

Higgins began the talk by explaining the typical reservations he holds for very futuristic project proposals (personally, having spent most of my adult life exploring the dynamics of space elevators, I hold few such reservations).  But, current breakthroughs in some key technological areas have him believing that he may live to see a fraction of light-speed transit to an exoplanet.

Today, we can detect the presence of exoplanets (planets orbiting stars other than the Sun) and even get a sense for their habitability (temperature, and whether it may have an atmosphere).  There is, however, no reason to believe that telescopes near Earth will enable us to learn any more than this about such planets, which are located at minimum around five light years away.  The only way we can hope to learn if life did or currently does exist on such a planet would be to go to it and take a picture, and send the image back to Earth.

While such a mission was laughable even five years ago, it is conceivable that we are now as little as two or three decades away from sending such probes to far off lands.  The challenge is to get a tiny satellite (a few inch diameter thin disk on the order of grams) to move at some fraction of the speed of light.  The number envisaged in the talk was 0.3c.

The 'TinySat' would be propelled to such a mind-boggling speed by a concentrated collection of coherent photons striking its surface... Basically, we would focus sunlight in a fancy way up to the satellite, where it would strike it (each photon carries a tiny amount of momentum, which it can transfer upon colliding with a surface).  The idea is to focus these streaming photons onto the satellite for a matter of minutes, accelerating the disk to, perhaps 0.3c.  If this were accomplished, TinySat would reach an exoplanet that is, say, 6 light years away, in about 20 years.  Then, it could snap some pictures, and send the images back to Earth, where it would arrive exactly 6 years later.  So, in total, in this scenario, pictures of the exoplanet arrive 26 years after the mission launches.  "Launches" ... This mission gives new meaning to the term launch.

What makes this plan reasonable to even discuss is threefold: (1) the emergence of the field of photonics, (2) advances in reflective materials (the surface of the satellite disk could reflect 99.9995% of the photons, and avoid melting during the photonic barrage), and of course, (3) the miniaturization of electronics, which means a useful satellite could be on the order of grams.

The project is known as "Breakthrough Starshot".  Some of the major challenges were outlined by Higgins.  He seemed most interested in how space dust might collide with a TinySat moving at 0.3c.  Would it destroy it?  In my mind, the most exciting challenge is those few minutes of acceleration.  At such high speeds, even the smallest non-zero torque would cause a rotation and a TinySat that moves very fast, but not in the direction that was intended.  Keeping the satellite pointed correctly during this acceleration is a monumental control challenge.  But, while we are on the subject of 'minutes', why not add a few more minutes of acceleration and get to 0.5c?  I mean, it would save us years of waiting for the probe to reach its destination.

Here is another challenge: can we even take a useful picture while moving at some fraction of the speed of light?  Maybe yes, if we account for the Doppler shift - I honestly do not know.  But that is what made the talk so exhilarating.  The numerous challenges posed by this mission are new, and many of them solvable and even testable in a lab here on Earth.  If I were looking for graduate work in engineering or physics, I would surely consider tackling some aspect of this project.

At the end of his 15 minute talk, Higgins was surrounded by eager young students with questions and novel ideas.  The enthusiasm in the room was palpable.  What I can say with confidence is that although the Breakthrough Starshot is a long shot (in every sense of the word), a lot of kids are going to have a lot of fun trying to make it. 

Thursday, October 18, 2018

You Are a Miracle

Consider all of the extremely improbable events that led to your being here today...

After the Big Bang, matter needed to become complex enough to form stars.  These stars burned for billions of years, and it was necessary that many of them ended their life cycle in supernova events, which led to the formation of new stars, more complex matter, and planets that orbit these stars.  Of these planets, some were in habitable zones - not too hot, not too cold.  For life to evolve, a conducive chemical soup was necessary, and then, perhaps the most unlikely event of all: one that synthesized a single-celled organism.  Then came evolution, whereby more and more complex organisms evolved - each necessary species along the line managed to avoid extinction before its critical mutation that led to the next branch in the tree.  Finally, the human race emerges (perhaps the most fragile form of all life thus far), and manages to survive millennia of hardship.  And if that were not enough, of all of the billions of humans to have come and gone, your parents met, and pro-created you.

How can you not feel at least a little bit special?  How can you see your existence as anything less than a miracle?

I think this is what is most beautiful about life: a seemingly endless set of possibilities out of which one actual outcome emerges.  I cannot help but have a certain affinity for each and every one of these improbable outcomes.

In this frame of mind, everything is worthy of attention, every topic deserves to be studied.  It seems to me that this is the place where science should begin.

Thursday, August 17, 2017

Everyone knows Mechanics

 My daughter in the waiting room at the Dr's office...

We all learn Mechanics from a very early age.  The same could be said for much of the sciences.  We just come to know it in a very hands-on way.  The challenge for science educators becomes taking that practical understanding and leveraging it towards a strong theoretical one.  Physics does not live on paper - the analysis students must master is arrived at in a more organic way when it reflects the real world it exists in.

Summer 2017 Projects

Here were my two summer projects for 2017...

1.  My fence.  Two posts dug by hand and two long spikes hammered in.  One interesting challenge was removing the old worn-out fence that was in the exact same location.  A post requires something like 600 lbs of lift force in order to remove it due to the concrete at the base.  I drilled a large hole through these posts, inserted an old bench press bar, and pryed them up.  The bar bent, but it did the job.  Yay torque.

2.  My kids' tree-house.  I had at least as much fun making it as they do playing in it.  I propped up an old 3 by 4 foot pallet about 4 feet off the ground and built around it.  Requires a circular saw, a bench and a drill...and about 300 bolts.  You can see it in the corner where the two fences meet.  I also built a couple of obstacles for my kids who are training to be American Ninja Warriors, despite being Canadian citizens.

That Time I Nearly Died

My scariest moment in recent memory involved the most dangerous piece of home equipment: the ladder.  I have since discovered that a 12 foot ladder should be supported in three places while in use.  Go figure.

I have chainsawed through numerous small trees and long branches, but this one was different.  I needed to make a cut about 16 feet high - otherwise, the falling tree would have snapped the telecommunication wires.  It is not recommended to use a chainsaw while perched atop a ladder, but gosh darn it, the tree cutting company I called told me I would have to wait 5 weeks for them to do it, and I had a tree-house to build...

The tree in question was some sort of weed tree, with an 8 inch diameter, about 40 feet high and leaning significantly.  I leaned my 12-ft ladder up against the tree I was cutting.  Now that might sound stupid, and it turns out it is, but hear me out.  The ladder's friction contact was a couple of feet below the cut point...

With a friend at the bottom of the ladder (like he could actually do anything from there besides have a great view of my demise), I stood on the second to top rung of the ladder, leaned forward with two hands on the chainsaw, and began to cut. With the cut 80% the way through, I heard a snap, which is expected.  What I did not expect is that the cut would cause the portion of tree BELOW the cut to split in half.

I am 12 feet in the air, with two feet on the ladder, two hands on a chainsaw, and I am going for a ride.  The ladder revolved about its base by about 15 degrees (I descended a few feet) until, thankfully, it made a firm contact with the tree somewhere else.  I, in a state of shock, slowly scaled the ladder back down to the ground, and confirmed that all of my body parts were still present.

In hindsight, even had the tree not split, the situation is still far from safe: when the upper portion is cut off a hanging tree, the lower part that is not cut is suddenly supporting less weight, and could shift its angle accordingly to a new equilibrium position.

Next time, I will attach the top of my ladder to something solid with a rope before making such a cut, or, more likely, I will wait for the tree cutting company to do the job for me.

Wednesday, September 7, 2016

Space Elevator Operator

A couple of years ago there was a student in my Mechanics class named Ivan Miloslavov.  He was that one in a thousand kind of student who had
1.  a knack for math and science,
2.  an interest in math and science, and also
3.  some particular skills - in his case, computer programming. 
This trifecta can produce some amazing things, and I want to share one of them with you.

During his time at College, we collaborated on an app called "Space Elevator Operator" (click here to try it...the link will also have a permanent home on my space elevator page).  I am really proud to have been involved with its creation for several reasons, but one of them is that I got to witness a young brilliant student putting his skills to work to produce something tangible and useful in the real world.

The app allows users to simulate placing payloads into Earth's orbit with a space elevator.  It serves two main purposes: 
-The app allows one to quickly demonstrate how a space elevator could work. 
- It is an educational tool that is useful for introductory physics students to learn about orbital mechanics.

One other thing this app does is give all of my students an idea of what is possible if they put their minds and efforts towards something.  The Space Elevator Operator app was shared at the 2016 Space Elevator Conference in Seattle this past month.  It was also recognized by ISEC (the International Space Elevator Consortium).

I wish Miloslavov much luck in his academic and professional future, and sincerely hopes he looks back at his experience on our little project with pride.

Sunday, March 6, 2016

I'm Off Blogging for MakerBloks

Hello my science peeps.  I have been absent from my blog as of late because I have been 'acquired' by another blog, that of "MakerBloks".

MakerBloks is a company specializing in hands-on science education for ages 6+.  The nature of my posts will be a bit less about physics content, and a bit more about science education for kids.  To see my first posting at my new 'home', follow this link.

I may pop in occasionally on The Engineer's Pulse and will certainly keep the blog active and moderate the comments.  Thanks for reading!

Thursday, January 14, 2016

The Martian is a Scientifically Sound Oscar Contender - Almost

If you have ever read a sci-fi film review on my blog, you are perhaps accustomed to the complete thrashing of the impossible events portrayed therein.  In the recent film, "The Martian", however, there will be no such thrashing - at least, not from me.  It is my favourite film of this past year, and yes, I saw "Star Wars, the Force Awakens" (and yes, it too was awesome).

The Martian is reminiscent of another great film, Castaway, in which a deserted human must survive on his own for multiple years.  Although the conditions are harsher on Mars than any island on Earth, Matt Damon's astronaut character did eventually establish contact with others, while poor Tom Hanks was stuck alone with "Wilson".

Monday, November 9, 2015

I Am Seeking Your Advice on a New Project

I have been blogging about science for five years without asking for any favours from my readers.  Today, I want your advice on something.

Why you?  The fact that you are here, on this site, means that you are probably science-minded and thoughtful.  Perhaps you also value the communication of science ideas.  Finally, maybe you are the type of person that would like to discuss science and engage in experiments and design in a casual setting with family, friends, and even strangers.

Over the coming year, I would like to develop a new kind of workshop.  At this point, I have a vision for what it might consist of, but the details are a blank canvas.

The workshops that I envision could take place in a library or school, perhaps once a week.  Each workshop could have a theme, and would entail a presentation, discussion, experiment, or design, or a combination of these.  I foresee groups of four to six people interacting in a relaxed setting.

I am looking for your advice for such a project.  Should there be recommended age groups?  Have you already participated in such a thing, and if so, what was good about it and what wasn't?

Why am I doing this?  For a few reasons, but the bottom line is that I don't think there is a place for families and friends to do real science together.  It seems to me to be an underserved market.

If you have any comments, please leave them here, below.  If you are in the Montreal, QC area and would like to be involved in the creation of or attend such a workshop, please feel free to send me a message at stephen.cohen(at)

Thanks.  SC.

Friday, September 11, 2015

This Radiologist Needs to Brush up on her Mechanics

Last week, I injured my shoulder playing soccer; it slammed to the ground after a nasty tackle in my 'friendly' soccer league.  After some nagging from my wife and a few of my students (who got to see what my left hand writes like at the board), I went to get some X-Rays of my right shoulder region taken.

Once in the room with the young radiologist, I was shown where to stand, somewhere between an emitter and receiver of the X-Rays.  She needed to make slight adjustments to my position between exposures.  She would place her hand on my shoulder and/or hip, and push or pull me to the right spot.  And each time it was time to move me, she would state, "Sir, please let me move you."  Eventually, this became, "Sir, please relax and let me move you."  Her frustration seemed to grow as she finally uttered, "Sir, please stop resisting being moved."

I must say, throughout all of this, it took every ounce of my patience to not say: "Enough! I can't take it anymore! Let me explain some basic laws of mechanics to you..."

First off, you cannot push or pull me without being pushed or pulled yourself.  That is Newton's third law, which, if ever violated, would send shock waves through the scientific community.  So, if you expect to push or pull me without getting pushed or pulled back, you must be new at this job.

Second, the extent to which I push back when you push me is related to my inertia or mass.  The amount that you accelerate me from rest with your force has a limit.  It is not a matter of "relaxing my muscles" - the only way you will feel no resistance is if I have no mass.  By saying "Stop resisting being moved," you are essentially telling me to "Stop having mass."  Mass, or inertia, is defined as resistance to linear acceleration.

In the end, I thought it would be smart not to lecture the radiologist about Newton's Laws of Motion.  I held back my urge to scream "Have you never heard of Isaac Newton?"  After all, she was in charge of the amount of high-frequency electromagnetic waves that would be periodically travelling through my body.  She could have responded, "Have you never heard of James Maxwell?"