Originally posted by Donkey Punch
Bump !
What everyones thougths on this .....
Hi guys I'm new around here, but i have a problem that is annoying me so much that it is literally keeping me up at night. I've recently started collecting comics, (and generally prefer Marvel comics) but after seeing the Superman movie i have gained sort of obsession. I know a little about physics, and It REALLY REALLY bugs me about Superman's powers especially seeing as hes a pseudo scientific character. The bit that bothers me the most is the energy crisis scenario. How was he able to gain the amount of energy needed to lift NEW krypton in the space of about two seconds.
I like the Pre Crisis idea that although his powers came from being under a yellow sun, it was never explained how this gave him his powers. It was Bryne who apparently created the notion of Superman absorbing yellow Sunlight to give him powers. Since Mark Waids, Birthright origin Superman hs been resorting back to his Silver age depiction. Does that mean he no longer absorbs Yellow sunlight to give him powers. If so where does he get his powers from ?
It’s a sort of article of faith among Superman fans these days that Superman’s power is absorbed from the Sun – that is, that his body absorbs the energy from sunlight and stores said energy for use at a later time, as a “living solar battery”, as John Byrne put it. If I recall correctly, he was the first writer to describe Supes’ powers this way, with previous references not being as specific – that is, the powers were explained as being caused by exposure to yellow sun radiation, without reference to the exact nature of the effect. It was all rather vague.
I admire anybody who tries to come up with a plausible-sounding explanation for comic-book superpowers; I do it all the time myself. But being the physics nerd that I am, I decided to do a back-of-the-envelope analysis of this idea.
It doesn’t work.
The short answer is that Superman expends energy at a far higher rate than he could possibly absorb it. But let’s run some numbers.
The flux of solar radiation at Earth’s orbit is roughly 1,400 watts per square meter (http://en.wikipedia.org/wiki/Solar_constant). Now, any object absorbs radiation through its surface area. The surface area of the human body is roughly 2 square meters (http://hypertextbook.com/facts/2001/IgorFridman.shtml). Note that I took the highest of the figures listed for surface area, and rounded the energy flux from the Sun up. Since this is a rough calculation, estimates and assumptions are unavoidable. But in the spirit of generosity, I will always select those assumptions on the side of results which are better for this theory. Also, as far as I can remember, I will point out when I’m doing so.
So, since Kal-El’s surface area is 2 meters square, let’s say he absorbs solar energy at a rate of 2,800 W/m^2. Note that I have assigned an efficiency of 100% to this process, and that I have ignored the fact that only one side of his body can face the Sun at a time, and I’ve also ignored night, being indoors, cloudy days, energy scattered from the atmosphere before it ever reaches Superman, etc…all of which would reduce the average rate of absorption.
Next, let’s figure out how much energy would be required for Superman to accelerate to Mach 25 (roughly 8250 meters per second at sea level. This is roughly orbital speed) once. Using figures from Superman: The Movie, Superman weighs 225 pounds. Converted to mass (and metric…sorry, fellow Americans, metric really is better), this comes out to roughly 100 kilograms. I have actually rounded slightly down in this case, but 100 is a nice round number and it makes no significant difference, anyway. Using the old formula for kinetic energy, KE = ½ m*v^2, we get:
KE = 3.4 billion joules (I rounded down)
Note that I have ignored air resistance. Including it would make the result much higher.
Now, how long would it take Superman to absorb enough solar energy to accomplish this feat? Well, let’s do it:
3,400,000,000 J / 2800 W = 1.2 million seconds (rounding down)
This is just under two weeks. If Superman has to go faster, the problem gets even worse…as the square of the velocity, in fact. So if Superman has to go twice as fast, it takes 4 times as much energy, etc.
Take an example from SR: the lifting of New Krypton. Assuming that NK has the same density as the rocks and soil that it’s made from (roughly 3000 kilograms per cubic meter near Earth’s surface) and also assuming that NK has the same volume as a sphere with a radius of 10 km (I like numbers that make the math easy…can you tell?), and also that Superman accelerated NK to sufficient speed that it would completely escape Earth’s gravity (roughly 25,000 MPH), we get a total energy of:
KE = 2.6 x 10^20 joules (26 followed by 19 zeroes, for those of you not familiar with scientific notation)[/B]
As I stated earlier I prefer the Pre Crisis idea that although his powers came from being under a yellow sun, it was never explained how this gave him his powers. It was Bryne who apparently created the notion of Superman absorbing yellow Sunlight to give him powers. Does the Mark Waid Silver age interpretation allowing him access to a more powerful energy source ?