Troubles with Super-Speed

I've just found a funny new blog created by Randall Mundroe (the man behind XKCD). The first post deals with the problems caused by a baseball flying at 0.9c, so it gives a nice idea of what would happen if some Superwoman decided to move equally fast through an atmosphere.

what-if.xkcd.com/1/

lfan wrote: Interesting read....cannot verify/disprove the science to it, but the author seems like he knows what he's talking about. For fictional purposes going forward -- and fantasy -- I'll use a little poetic license and disregard that I read this. Thx though!

ElF

I agree, however, an object, or supergirl, wouldn't have to move near that fast to appear a blur, or even seem to "disappear" and "reappear". A bullet moves super sonic and I'd challenge any human to try and track it with the naked eye. Triple that speed or more and she's still nowhere near the speed of light. The only real problem then is the same torn clothes, superheated skin, and kinetic energy we usually address in our stories.

In space, there is no atmosphere to worry about, so it's a moot point to me.

Additionally, maybe everyone with this kind of superspeed uses some kind of warp field. Or a worm-whole... either way generated by willpower. Problem solved, you're welcome

jnw550 wrote: In space, there is no atmosphere to worry about, so it's a moot point to me.

Even in space, there are relativistic issues to be concerned with. My personal approach, assuming I'm not trying for a science-fictiony authentic feel to a story, is to just ignore any inconvenient laws of physics and invoke poetic license. If the reader cannot accept a supergirl running at a million miles per hour, said reader is not part of the target audience for the story in question.

Interesting to note that a Superwoman with that kind of speed could destroy the world just by moving quickly.

Also, this isn't off-topic is it?

jnw550 wrote: A bullet moves super sonic and I'd challenge any human to try and track it with the naked eye.

I could be fooling myself - but shooting a just barely sub-sonic .22 round at targets 50 meters away I'm confident I often see my bullet. Granted - I'm looking down range with the bullet - and not watching laterally.

Magic happens when the bullet is caught in flight or directed when bouncing back off the hero/villain.

I like a fair bit of realism to ground any story – both to emphasize and exceptional-ism of the hero but also to make suspension of disbelief easier when I’ve not been beaten over the head with silliness. I think that’s why I like some of Shadar’s stories so much or even the new James Bond movies.

It also prevents lazy writing – which I worry I’m guilty of sometimes. “Superman can lift all and gets his way easily and always” doesn’t make for a great story.

Come on - Is a baseball (M) at light speed (C) really enough energy (E) to cause a fission reaction?

lfan wrote: Interesting read....cannot verify/disprove the science to it, but the author seems like he knows what he's talking about. For fictional purposes going forward -- and fantasy -- I'll use a little poetic license and disregard that I read this. Thx though!

ElF

I beg to differ. While he is correct on the speed in that the ball would appear to an observer in the dugout to move 1 foot closer to the plate per nanosecond, he is taking about Fusion, while describing Fission. This raises serious questions about his fundamental understanding of nuclear Physics.

The classic Fusion example is that of Deuterium (H2) colliding with tritium (H3) and ejecting a neutron with a sizable amount of kinetic energy. Mass is not conserved and this is a perfect example of E=MC squared Let that proton dissipate its kinetic energy in something that will get hot, have that turn water into steam to power a turbine and run a generator, and presto, you have all the electricity you could ever want!

And forty years after they started blasting H2/H3 pellets with Lasers to do this, they still can't get more energy out of the reaction than what it takes to make it happen in the first place. Lucky for us, our sun figured out on its own how to do it!

A bullet moves super sonic and I'd challenge any human to try and track it with the naked eye. Triple that speed or more and she's still nowhere near the speed of light.


Let's look at that. A 30.06 can fire a round at almost 3000 ft per second. That is a little over 2000 MPH, or about as fast as an SR-71 BlackBird flies. If an SR-71 flew past you about a mile away, to fly from 1.5 miles to your left, to 1.5 mile to your right would take about 5.2 seconds. You would most likely see that. If a bullet was fired from 100 feet to your right ten feet in front of you, it would be 100 feet to your left in 66 milliseconds. Human reaction time is around 200 milliseconds. You would never see it.
A supergirl staring at 500 feet to your right and getting to 500 feet to your left would happen in 330 miliseconds. Even if you "saw" her at 500 ft to your right, by the time you reacted and started moving your eyes she would be 100 feet to you left.

ace191 wrote: he is taking about Fusion, while describing Fission.

Uhm, no, he's not. Physics really doesn't care if our technology is unable to produce a sustainable fusion reaction with more than a handful of protons involved.
If the fusion of heavier elements wasn't possible, we wouldn't be having this discussion. After the Big Bang, or rather at the moment where we don't have to know subatomic particles to describe the situation, the universe consisted of hydrogen pretty exclusively. Everything else was created in stars going Supernova, spewing out their mass which in turn formed new stars. IIRC, our sun is currently considered to be a 3rd to 4th - generation star. And given the fact that a baseball travelling at .9c carries huge amounts of energy, it's pretty safe to assume it does have the ability to cause a fusion reaction in higher elements.
(Especially since in my opinion, the energy deficit of fusing two carbon atoms should be far less than that of trying to split one of them. There's a reason we're using elements with roughly 20 times the mass of carbon in reactors. But that's just me remembering bits of my physics lectures and being to lazy to actually calculate if those reactions are efficient or not - if anyone feels the need to check that, I'm more than willing to cede this part.)

What I actually find more interesting is that I never thought of this being a problem for our travelling superwoman (given that she should be able to fly around the earth about 6 times in a second moving that fast).
Pretty much like steelknight3000 I was more struck by the idea that any superwoman able to move even at a fraction of that speed should be able to cause a fusion reaction by, for example, snapping her fingers.
(Assuming the factor between finger speed and whole body movement stays roughly the same.) I'm guessing a finger to move at roughly 30-40km/h (~20-28mph, I think) which means it's moving easily at three to five times the speed we can sustain for a longer duration. (IIRC the top running speed for a human being was somewhere close to 44km/h during a 100m sprint. The record for a marathon should be somewhere around 20km/h.)

And for any superwoman actually able to fly at .9c without any warp bubbles or other gimicks, there would be the possibility of creating a single nuclear explosion (doesn't really matter if it's fission or fusion) that forms a ring around our (or any) planet. Which, despite it's environmental ... let's call them drawbacks ... I'd love to see. just out of curiosity.

It's too late at night to calculate the 1/2 M V2 of a 5 and 1/4 ounce baseball.

To get around these problems for the Supergirl of Smallville, Argo and I agreed that Lana's speed limit would be 0.1c.

I was not talking about the creation of all elements during the Big Bang.

If memory serves me right, iron is the break point. Lighter than that, Fusion, heavier fission.

You need something like 15 million degrees Kelvin and a whole lot of pressure to fuse
Hydrogen into Helium.

One of the great concerns in the Manhattan project was that they would start a chain reaction that would consume and destroy the whole world. There were two camps on this. One that said that they would have a tough time getting any of the fissionable material
to go, and the other that was afraid the whole world would be consumed.

The Nobel Prize-winning (1938) physicist Enrico Fermi was willing to bet anyone that the test would wipe out all life on Earth, with special odds on the mere destruction of the entire State of New Mexico

Well, as we all know, that experiment has been done, and In the Fat Man Plutonium bomb, about 17% of the material underwent fission.

If you can only get less than 1/5 of relatively easy to fission material to do so inside a nuclear bomb, I don't think that a baseball moving through the air is going to create a nuclear explosion and mushroom cloud.

Bottom line is that if the greatest minds in physics were not sure what would happen when they pushed the button, I don't think we should worry if we disagree on what the 0.9c baseball would do. Just my 2 cents.