Semi-metric Jan 25, 2022
The engineering community commonly uses the metric system, both because a lot of the early math and science was performed by Europeans, but also because it makes a bunch of calculations simpler.  English units have pounds of mass and pounds of force, which are both equivalent and not equivalent, depending on some criteria I have to look up every time I use them.  So it's common to scoff at people who use English units because it adds unnecessary complexity. 

But not all engineers use metric units.  Mechanical designers and metal machinists use English units, [I've heard] because the cutting tools use English units.  We don't have 6.4-mm screw holes; we have 1/4" screw holes because we have 1/4" drill bits.  Some raw materials come in thicknesses measured to the nearest 1/8" or 1/4". 

But at the same time, metal machining often specifies tolerances using a sort of semi-metric system, e.g. something is measured at 1/8" +/- 0.010" (spoken "ten thousandths").  Similarly some engineers use feet as a unit of distance, but if the magnitude of the values they deal with is greater than 10,000, they use the term "kilofeet", which is both beautiful and ugly at the same time. 

Electrical power is measured in Watts, but mechanical power is measured in horsepower.  [Hint:  they're the same thing, i.e. units of power.]  But it feels wrong to say I have a 147 kW engine in my car, or a 1.36 hp microwave in my kitchen.  It all comes down to what you're used to. 

The metric system is really just a standardized unit (m for length, kg for mass, etc.) plus a Latin or Greek prefix denoting the decimal point.  English units almost sort of use a crappy version of this with things like inches (10^0), feet (inches x 10^1.0792), yards (inches x 10^1.5563), miles (inches x 10^4.8018).  I don't know what the solution is, so I'm gonna go walk a few hundred mega-inches to de-stress. #science
Traditional vs. mRNA vaccine Jan 11, 2022
I'm not an expert so I'm quite possibly wrong about this, but one way to think about the difference between a traditional (viral vector) vaccine and an mRNA vaccine is this:  A traditional vaccine is like if you took a partially-eaten cookie to a bakery and asked them to make you a similar cookie.  An mRNA vaccine is like if you went to a bakery and asked them to make you a cookie with the recipe you just handed them. #science
Rocket brain Dec 15, 2021
A study found that rocket scientists and brain surgeons aren't smarter than the general public.  I was actually just thinking about this recently.  Those disciplines aren't some sort of obscure, hidden knowledge obtained through a secretive quest.  It's just people who had some sort of baseline ability and interest in a topic, then studied and worked hard for a while.  Not to understate their accomplishments or overstate my abilities, but I could do that.  Most people could.  There's a huge caveat that it depends where you live and how your local schools are and all sorts of things.  But in general, most people can do most things. 

I think it's weird that rocket science and brain surgery are put on a pedestal, when really any specialized discipline is essentially equally difficult and impressive.  Electricians regularly work with an invisible death force, yet the average person has no idea how it works much less how to wire an electrical outlet.  Modern life would essentially stop if electricians stopped showing up to work.  Similarly, I hired a guy to redo some drywall in my house, not because I'm unable, but because I'm not good at it.  The work he produced nearly brought tears to my eyes because it was so good.  In other words, trust experts. 

I think rocket science and brain surgery get singled out at least partly because those subjects are inherently more risky.  Or more specifically, the likelihood of an incident is higher, and the consequences are quite bad.  Getting a rocket to lift off and fly straight is difficult, and if it fails it causes a big boom with lots of fire (high likelihood, high consequence).  This happens frequently enough that it's a legitimate concern for engineers and safety people.  A similar discipline like structural engineering is just as difficult, and the consequences of a bridge or building falling down are just as bad, but the likelihood is much lower (low likelihood, high consequence).  It's the same for brain surgery, but in the reverse order.  If a dentist screws up a tooth surgery, they can just try again next time (low likelihood, low consequence).  If a surgeon screws up a brain surgery, that patient is permanently altered (low likelihood, high consequence). 

[This has been your introduction to Risk Assessment.]

Finally, rocket science doesn't really exist.  Science is the application of the scientific method to further knowledge about a subject.  Not to put too fine of a point on it, but we pretty much know everything we're gonna know about rockets (dangerous claim to make, but I did it).  The science is essentially settled (combine some chemicals or ignite them to produce an energetic reaction).  What we're really talking about when we say "rocket science" is "rocket engineering", i.e. how do I apply this scientific knowledge to shoot a person at another planet?  But "rocket engineering" just doesn't have the same ring. #science
Girus Sep 7, 2021
Here's a weird video about giruses (giant viruses) with this terrible quote: 
Most Giruses we've found so far hunt amoebae and other single-celled beings.  When they find a victim, they connect with it and use its natural processes to enter the cell.  Like all viruses, their goal is to misappropriate the victim's infrastructure and procreate.  Imagine a mouse crawling into your mouth and using your guts and bones and fat tissue to build a mouse factory.
No. #science
Torque Apr 28, 2021
Torque is probably my favorite physics concept because it's so simple and appears in all kinds of places.  Torque is a measure of force times distance.  You can generate more torque by applying the same force at a greater distance from a rotation point.  It's the reason why wrenches tighten things better than screw drivers.  It's the reason why those little Allen keys are double-sided -- one side is for quickly screwing something in; the other side is for tightening.  It's the reason you do bicep curls by holding a dumbbell in your hand and not on your forearm.  It's the reason why, when my ax gets stuck in a piece of wood, I grip it as far away from the ax head as possible to get it unstuck.  It's the reason why branch-cutting shears have really long handles.  It's the reason why lug nut wrenches are sometimes double-sided (double the torque) or have really long handles. 

When in doubt, use a longer lever. #science
Fittest Jan 12, 2021
From what I understand about evolution (hint:  not much), the phrase "survival of the fittest" is a little misleading because it brings to mind a tough individual surviving in a difficult environment by being specially adapted.  But really, the organisms that survived weren't simply the ones that "fit" the best.  They were the ones who reproduced the most successfully.  Being "fit" in an environment can probably lead to reproducing, but that doesn't mean that the ones who reproduced were necessarily the most "fit".  They were just the best at reproducing. #science
On blood Mar 4, 2020
Donating blood likely has no short-term effects on heart rate, blood pressure, or blood chemistry (assuming the donor doesn't pass out) because the human body has homeostatic mechanisms that constrict blood vessels to increase blood pressure as well as kidney functions that increase fluid retention.  It takes about 8 weeks to regenerate a pint of donated blood. 

Blood transfusion recipients typically get just one pint.  A normal human body contains about 10-12 pints of blood.  Children have about the same volume of blood as adults.  Except newborn babies, who have about a cup. 

Blood donor DNA is detectable in recipients, but only through specialized tests that specifically look for it.  Otherwise it's in small enough quantities that it can be ignored. #science
On steroids Mar 2, 2020
Bottom line up front:  I'm not on steroids. 

I think one of the biggest misconceptions about anabolic steroids is that they magically make people stronger, better, and faster.  That seems to be how they're perceived in sports:  An athlete takes steroids, a known performance enhancing drug, and is temporarily or permanently banned or is forced to have an asterisk next to their name. 

I think a more accurate way to look at it is that steroids don't make you stronger, they give you the ability to work harder.  You still have to actually work harder, but your body is able to recover faster, which enables you to put in more hard work.  Steroids aren't just a magical pill that give you an ability.  They give you recovery, so you can keep doing what you would otherwise be doing to develop your ability. 

I'm not trying to make the case that steroids are good or that they don't provide an inherently unfair advantage.  I just think their vilification detracts from the immense amount of time and effort their users actually put into their craft. #science
Flu shot effectiveness Jan 24, 2020
The second most common excuse people use for not getting a flu shot, after "I didn't get one last year and I didn't get the flu", is that it's not even 100% effective.  It's true; the CDC says, "recent studies show that flu vaccination reduces the risk of flu illness by between 40% and 60%", which is indeed less than 100%.  But here's another way to look at it:  A flu shot is 50% effective, while not getting a flu shot is 0% effective. #science
Living on Mars Jul 26, 2019
A lot of people think we'll live on Mars someday, and possibly someday soon.  These people are idiots.  Here's why: 
  1. Mars ain't got no air.  Air-breathing humans would have to either constantly wear ventilation masks or live in pressurized bubbles.  It would be like living underwater.  All the time.  Forever.
  2. Mars is fucking cold.  I feel like this point gets overlooked a bit because Mars is in the "habitable zone" i.e. there can be liquid water in some places sometimes.  But a summer day can swing from 70°F to -100°F.  That's a negative sign there.
  3. There's no sun.  There's some law of physics that relates the sun's power output to the distance a planet is from it.  Mars is farther from the sun than Earth.  Less sun means less heat, less solar power, less plant energy, less everything.
  4. Mars ain't got no stuff.  Stuff like water (ok there's some), plants, animals, building materials, factories, fast food establishments.  Point is, you'd have to bring literally everything you'd ever need for anything.  Yes you can 3D print some stuff, and yes you can maybe grow potatoes in your poop, but for the first many years of settlement there you'd have to come with your bags packed.  People underestimate how ridiculously difficult and expensive it is to shoot a rocket from Earth to Mars.  Yes it's been done before, but it's kind of a big deal every time it happens.
  5. We're not gonna terraform it.  Yes it's hypothetically possible, and hey we've terraformed Earth so it can't be that hard.  But the amount of energy required, and the international (interplanetary? intergalactic?) agreements it would require, and the choice of the best actual way to terraform, means it'll never happen.  It's a science fiction idea.
Earth is really good at sustaining human life.  It has the gravity we're used to, the air pressures and chemical components we enjoy breathing, the temperatures we can deal with, and the food we like to eat.  Maybe instead of trying to terraform a planet that has none of those things, we could try to make our current planet a little better. 

Many times throughout history, an unwise person made a proclamation about the future that turned out to be utterly false.  Perhaps I'm that unwise person. #science