What if physics xkcd

It peaks twice every month as it passes over the fast-moving equator, then reaches a minimum when it's over the slower-moving tropics. Its orbital speed also changes depending on whether it's at the close or far point in its orbit. This leads to a roughly sine-wave shaped ground speed:.

Ok, fine. There's one other cycle we can take into account to really nail down the Moon's ground speed. This means that the Moon's latitude changes the way the Sun's does, moving from the northern tropics to the southern tropics twice a year. However, the Moon's orbit is also tilted, and this tilt rotates on an When the Moon is over a point farther from the equator, it has a lower "ground speed," so the lower end of the sine wave goes lower.

Here's the plot of the Moon's "ground speed" over the next few decades:. The Moon's top speed stays pretty constant, but the lowest speed rises and falls with an When you do finally enter the atmosphere, you'll be coming down near the edge of the tropics. Try to avoid the tropical jet stream , an upper-level air current which blows in the same direction the Earth rotates.

Regardless of where you come down, you'll need to contend with supersonic winds, so you should wear lots of protective gear. Make sure you're tightly attached to the pole, since the wind and various shockwaves will be violently battering and jolting you around. People often say, "It's not the fall that kills you, it's the sudden stop at the end. At some point, to reach the ground, you're going to have to let go of the pole.

For obvious reasons, you don't want to jump directly onto the ground while moving at Mach 1. Instead, you should probably wait until you're somewhere near airline cruising altitude, where the air is still thin, so it's not pulling at you too hard—and let go of the pole. Then, as the air carries you away and you fall toward the Earth, you can open your parachute.

Then, at last, you can drift safely to the ground, having traveled from the Moon to the Earth completely under your own muscle power. When you're done, remember to remove the fire pole.

That thing is definitely a safety hazard. Prev Earth-Moon Fire Pole My son 5y asked me today: If there were a kind of a fireman's pole from the Moon down to the Earth, how long would it take to slide all the way from the Moon to the Earth?

The Earth's surface spins faster than the Moon goes around, so the end that dangled down to the Earth would break off if you tried to connect it to the ground: There's one more problem: [2] Ok, that's a lie—there are, like, hundreds more problems. Instead of sliding, you'll have to climb. But more importantly, the extra mass also makes the Sun heavier.

This crushes it together more tightly and makes fusion happen faster. This means it will burn more brightly and run through its fuel more quickly. As you keep adding water, the Sun will go through a lot of wacky fusion phases. But one way or another, eventually the whole thing will collapse in on itself, blow off its outer layers, and become a black hole. What if you shined a flashlight or a laser into a sphere made of one-way mirror glass?

The glass in police shows is partially reflective on both sides. If Michael Phelps could hold his breath indefinitely, how long would it take for him to reach the lowest point in the ocean and back if he swam straight down and then straight back up? The human body handles pressure remarkably well. For example, see the results from the color survey or the feasibility analysis of an idea for an endless sunset.

I'm super excited to see these types of features coming on a regular schedule on the new blog What If! On a somewhat related note, if you like fun math puzzlers, then I highly recommend reading Journey Through Genius by William Dunham.

You're still definitely not going to make it—things don't turn out well for the Earth in this scenario—but what, exactly, would you die from? The Earth is big enough to protect people on the other side—at least for a little bit—from Max's sunbeam, and the seismic waves from the destruction would take a while to propogate through the planet. But the Earth isn't a perfect shield. Those wouldn't be what killed you. The sky is dark at night [ citation needed ] because the Sun is on the other side of the Earth.

There's a glow in the sky before sunrise and after sunset because, even with the Sun hidden, some of the light is bent around the surface by the atmosphere.

If the sunbeam hit the Earth, x-rays, thermal radiation, and everything in between would flood into the atmosphere, so we need to learn a little about how different kinds of light interact with air. Normal light interacts with the atmosphere through Rayleigh scattering. You may have heard of Rayleigh scattering as the answer to "why is the sky blue. Over time, a layer of copper carbonate formed through oxidation , and copper carbonate is green. When air heats up, the electrons are stripped away from their atoms, turning it to plasma.

The ongoing flood of radiation from the beam has to pass through this plasma, so we need to know how transparent plasma is to different kinds of light.