What If? Rejects #10.3: Turkey Day

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Q: What if every day, every human had a 1 percent chance of being turned into a turkey, and every turkey had a 1 percent chance of being turned into a human?

Randall’s response: No response.

My response: Allow me to put on my fiction writer’s hat. The obvious answer is that we wouldn’t be eating turkeys anymore, but it’s actually much more complicated and interesting than that. This is an exercise in worldbuilding: designing a fictional world and establishing self-consistent rules for how that world operates. And so, in the spirit of the season, let’s create…Turkey World.

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Predicting More Earthquakes Next Year? It’s Not Crazy.

No, this isn’t an End Times conspiracy theory. It’s an actual prediction from two practicing geologists: Rebecca Bendick of the University of Montana and Roger Bilham of the University of Colorado. They have published a paper in Geophysical Research Letters that (by a reasonable interpretation) predicts that we will have significantly more major earthquakes than usual in 2018, according to a recent article in Science. Is this a reasonable prediction? After digging a bit deeper, I have to say yes, but don’t panic; it’s not as bad as it sounds.

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What If? Rejects #10.2: Stunt Bike

So it turns out some people are actually crazy enough to try this.Previous post in this series: Knife Wounds

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Q: If I were on a motorbike and do a jump off a quarter pipe ramp, how fast would I need to be moving to safely deploy and land using the parachute?

Randall’s response: No response.

My response: If you mean just yourself and not the bike, possibly as low as 55 miles per hour, but only if you have the right parachute.

WARNING: Do not try this at home!

The real question here is, how high do you need to get to successfully deploy a parachute? An ordinary skydiver’s parachute is rated to deploy at 2000 feet. The reserve chute is rated for 700 feet. However getting to both of these altitudes would require going faster than terminal velocity—with a rocket-powered motorbike, perhaps. Terminal velocity is about 120 miles per hour, and that’s before air resistance, so you’re probably well outside the operating capacity of most motorbikes.

However, military parachutes for paratroopers can be rated for as low as 250 feet. To reach this altitude, you don’t need to get up to terminal velocity. In fact, you can calculate your takeoff speed using the simple equation:

V = SQRT(2gh)

Here, V is your takeoff speed, h is your maximum height, and g is the acceleration due to gravity of 32 feet per second squared. (I’m using feet because most of my readers will probably understand motorbike speeds best in miles per hour. As an astrophysicist, the correct figure is obviously 980 cm/s2.) Plug 250 feet into this equation, and you get a takeoff speed of 86 miles per hour. Granted, that’s without air resistance, but you’re also not going to be leaving the quarter pipe ramp from zero altitude, especially if it’s big enough to drive a motorbike on, so let’s assume it balances out.

But even this is not the limit. BASE jumpers routinely make jumps from less than 250 feet. In fact, some have jumped from as low as 100 feet. From that height, you don’t even need a parachute. You only need a swimming pool, since the official high-diving record is 172 feet (although dives from that height invariably result in broken bones).

To reach an altitude of 100 feet, you only need a takeoff speed of 55 miles per hour. You’ll probably want to make it 60 for safety (or more…a lot more), but in theory, if you take off with a speed of 55 miles per hour, and if you dismount from the bike, and if you have perfect timing, you could deploy a BASE jumping parachute at the top of your arc and land safely.

But note the video above: no one has actually jumped high enough to do this. Also, try not to land on the crashed-and-burned motorbike.

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What If? Rejects #10.1: Knife Wounds

File:Damascus Bowie.jpg

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Q: What is the probability that if I am stabbed by a knife in my torso that it won’t hit anything vital and I’ll live?

Randall’s response: A guy with a knife says, “…Asking for a friend. Former friend, I mean.”

My response: Surprisingly high—that you’ll live, that is, not precisely that it won’t hit anything vital.

At first glance, this question should be easy to answer because lots of studies have been done on the survival rate for various types of injuries, but on closer inspection, we have to extrapolate a bit. You see, these studies usually only study victims who made it to the hospital alive. And they also differentiate between chest wounds and abdominal wounds, both of which are covered under “stabbed in the torso”. Or they don’t differentiate between types of stab wounds at all. But we can look at the statistics and get a good idea.

Overall mortality rate of stab wounds is 7.7%.

Survival rate for stab wounds to the heart is 32.6%.

Overall mortality rate for penetrating injuries to the chest is 2.5%.

Stab wounds to the chest where the knife is left in to slow the bleeding have a survival rate approaching 70%.

For people stabbed by terrorists in Israel: 19% had only superficial injuries (probably the closest to the literal interpretation of the question, while 25% died.

And finally, Wikipedia cites an overall death rate of less than 4% for all stab wounds.

So on the whole, getting stabbed is a really bad day, but your odds of surviving are actually fairly good—at least for a situation where someone is trying to kill you.

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Movie Review: Thor: Ragnarok

Thor Ragnarok poster.jpg

The Marvel Cinematic Universe has had its ups and down, but lately, it’s hit its stride, turning out one hit after another, and Thor: Ragnarok is no exception. Indeed, even though the franchise hasn’t had a true flop since Avengers 2, this film is a massive hit for a trilogy that has had a mediocre showing for the first two Thor movies. (Although all three of the films I just mentioned still have worryingly high critical reviews.) Either way, Thor: Ragnarok was briefly Rotten Tomatoes’ highest-rated Marvel movie of all time, and while it has now slipped below Iron Man 1, it’s still some of their best work, and a great setup for the upcoming Infinity War.

Thor: Ragnarok follows on the second Thor movie, in which Loki took over Asgard by impersonating his father, Odin, and exiling the real Odin to Earth. Unfortunately, separated from the power of Asgard, Odin is dying, thus releasing his firstborn from her own exile: Hela, the goddess of death. And having the woman whom Hell is literally named after come to town is bad news. Thor’s hammer is destroyed, Thor is knocked to the far end of the universe, and Hela soon conquers Asgard, and that’s all in the first 30 minutes! And only Thor has the power to find his way back and stop his sister from bringing about the Norse apocalypse of Ragnarok.

If I had to make a criticism of this movie, it would be that it’s a bit rushed—trying to do too much in too short a time. Hela’s curb-stomp of the defenders of Asgard, including some notable secondary characters, just felt too fast to have the desired impact. But even with that, the movie is very-well produced. It’s fun, humorous without being campy, and manages to pack in great character arcs for all the major players.

Really, I think that’s the best part, for all the silly antics, we really get to see Thor, 142, Banner, Loki, and even Hela’s henchman go through real growth as characters, all in the space of two hours. And of course, we get to see Hulk beat up Thor. Basically, it’s a pretty great time all around, one of Marvel’s best, and definitely worth the ticket price.

My rating: 5 out of 5.

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What If? Rejects #9.2: Everyone Knows It’s Slinky

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Q: If you are in free fall and your parachute fails, but you have a Slinky with extremely convenient mass, tension, etc., would it be possible to save yourself by throwing the Slinky upward while holding on to one end of it?

Randall’s response: A picture of someone attempting the experiment, without explanation.

My response: Um…no. There’s a little something called conservation of momentum. If you throw the Slinky upward, you’ll be pushing yourself downward even faster by Newton’s Third Law, which kind of defeats the purpose. Even if the Slinky started pulling you back up by its spring force, it would lose energy, and it wouldn’t be able to slow you down any more than if you tried to bleed off your momentum by throwing it downward in the first place. To do that, however, you would have to cancel out your momentum of falling—in other words, apply the same force as throwing your own weight at your terminal velocity of about 120 miles per hour. Unless you’re a superhero, that’s not going to work so well, and if you are strong enough to do that, you’re probably also strong enough to withstand the landing anyway.

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Heavy Metals in the Cosmos

The recent discovery of gravitational waves from the neutron star merger designated GW170817 is said to prove that heavy metals like gold are produced in this extreme environment and not in supernovae, as was long thought. The teams that discovered GW170817 put out an astonishing 76 papers all at once, including 5 on the subject of nucleosynthesis, all pointing to this conclusion. But how did it come about?

There are a number of different nuclear processes which create most of the elements of the period table, nearly all of which occur in different types of dying stars. In fact, out of all the elements, only carbon and nitrogen are predominantly created by the classical, orderly core fusion you’ll see in introductory textbooks. Elements lighter than carbon are created by various cosmic processes, while all of the other elements are predominantly created by stars in their death throes. Here is a handy guide from Jennifer Johnson of The Ohio State University.

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