Now, he could have made it out of anything, like fishing line or even steel, and yet he chooses to replicate spider silk.

Spider silk.

This kid is trusting his life to a flimsy-looking strand of arachnid goo.

But it turns out, if Peter's web is anything like real spider silk, then his web-slinging antics are more realistic than they might appear.

Now, spider silk doesn't look very durable.

After all, a strand can be as little as 1/40 the thickness of a human hair, but, pound for pound, it's stronger than steel.

So if you twisted spider silk into a thread that was 2 millimeters wide, as thick as a strand of spaghetti, it could support 900 pounds before breaking, strong enough for a polar bear to hang from.

So a scrawny kid, like Spider-Man? He's got this.

And that's just for a 2-millimeter-diameter webbing.

If he needs more, he just makes it a little bit thicker, and it could support even more weight.

That's physicist Jim Kakalios, the author of "The Physics of Superheroes."

He says that the secret to spider silk's strength is its structure.

Real spider silk has two major components.

Extremely rigid nanocrystals that make the silk sturdy and stretchy, elastic polymers that make it pliable.

That combination of tough and flexible makes the silk extremely hard to tear, and, if you look at Peter's lab notes, it looks like he tries to mimic that same structure.

So, it looks like it is a set of organic molecules that he is using, and he's trying to combine them in ways to polymerize them, to basically take these complex molecules, and link them together in longer chains that would then presumably fold down and develop these nanocrystals and the elastic polymers.

But Peter may have gone one step further and actually made one improvement to his synthetic silk.

I think that, instead of these little nanocrystals of proteins that spiders use, he might be using carbon nanotubes to provide the strength and rigidity.

Carbon nanotubes are basically a sheet of carbon atoms that's been rolled up into a tube.

And if Jim's right, Peter is one smart high-school student, because these tiny tubes are actually some of the strongest material known to humans.

In fact, they're over 100 times as strong as steel.

And that's when they're microscopic.

So, a spaghetti-thin strand of this stuff, like what we see in "Spider-Man"?

It could support far more than just 900 pounds.

That would be able to support over 40,000 pounds.

Suddenly that ferry scene doesn't seem so far-fetched, especially since we have the technology to make those nanotubes in real life.

Scientists at the University of Cincinnati, for example, have figured out how to grow carbon nanotubes in a lab and then spool them into threads.

Sadly, those threads aren't meant for skyscraper-swinging antics.

The researcher's goal is a tad more practical.

If you could manufacture it and make threads out of carbon nanotubes, you could make lightweight clothing that would be stronger than Kevlar.

So, when you really think about it, the most unrealistic thing about Peter Parker's homemade webbing is that a high schooler figured out how to make it in his chem class.