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WARNING TO ALL SCI-FI/FANTASY NERDS: Physics is totally about to totally ruin some of your favorite stories. If you don’t want to end up throwing out your forty disc Back to the Future Blu-Ray boxed set in a fit of rage, you might want to skip this particular blog post.

Time travel is one of the most popular tropes in science fiction books and movies. There is no official stance by the scientific community on whether time travel is at all possible, because the concepts are controversial and highly theoretical. Plus, there’s a ton of math involved, so we’re definitely not getting into that.

Check out this clip from Harry Potter and the Prisoner of Azkaban:

Hermione uses her Time Turner to send her and Harry back about three hours into the past. We get to see that time pass in reverse, as the dark sky outside the windows brightens and people’s forms shuffle about in fast-motion rewind. What’s important to notice is that Harry and Hermione stay put as everything else moves around them. They end up in the same spot they were standing in when they started the Time Turner.

Imagine you visited Orlando six months ago and had some of the best pizza you’ve ever tasted at Lazy Moon on Alafaya Trail. You go back there today and find, to your horror, that the restaurant has closed. Never one to fret, you pull out your trusty pocket time machine and set the dial for six months ago. Then, you freeze to death and die in the vacuum of space.

You didn’t see that coming, did you? You should’ve. Here’s why:

What time of year was it six months ago? It’s winter now, so it must have been summer when you were enjoying your pizza. Well, why do we even have seasons? If you remember from grade school, the weather changes because Earth revolves around the sun. One complete revolution takes a year — by definition! — so six months ago, Earth was on the opposite side of the sun as it is right now. What was right here six months ago? Lifeless void, and (probably) very little delicious pizza.

“But wait!” I hear you shrieking. “Harry and Hermione only went back about three hours. Certainly, Earth couldn’t have moved that far.”

Actually, as it turns out, Earth moves about thirty kilometers every second… in relation to the sun, that is (we’ll come back to that in a minute). So, in the 10,800 seconds (3 hours times 60 minutes per hour times 60 seconds per minute), Earth would’ve backed up about 324,000 kilometers along its path through space. That’s over 200,000 miles. And what’s 200,000 miles away in any straight line from the surface of Earth? Vacuum.

Boom. Dead.

“I’ll show you!” you now scream. “I’m not as dumb as a couple of schoolkids from a magical place where they don’t even teach math! I’ll just wait six more months, then go back in time a year! Then, Earth will be right back where it was the last time I ate my tasty slice of goat cheese and pineapple pizza pie. Hah!”

Ew. Dude. Goat cheese and pineapple? Really?

Anyway, that’s not a bad idea. Shows you’re thinking. After all, we’re not cavemen; we have a really good idea where Earth is at any one time… in relation to the sun. That’s the second time I’ve mentioned that. Why does it matter? Prepare to have your mind blown.

The sun? Yeah, it totally moves, too. It revolves around the center of our galaxy, at a speed of about 217 kilometers per second, or about seven times faster than Earth revolves around it. And before you get too froggy, yes, the galaxy is moving through space, too.

The problem here is that there is no absolute “center” of space. To assume that you can stand in place while you rewind or fast-forward through time violates the Copernican principle, which says that the universe doesn’t revolve around Earth — let alone the former home of your favorite pizzeria. So, while it might or might not be physically possible to reverse time’s heady flow, all your munchie runs through time are going to end the same way:

Frozen space death.

One concept you will learn about when you study projectile motion is that perpendicular vectors do not interact.  This means that if you launch an object horizontally its vertical motion will be exactly the same no matter how fast the launch speed is.

 

This is because the object is dropping from the same height each time.  Vertically, the object encounters two forces: weight and air resistance.  The weight pulls the object down to the ground and the air resistance pushes up against the object.  No matter how fast the object is moving horizontally it falls vertically in the same pattern.  The horizontal speed will only affect where the object lands.

 

If you have two identical balls and you roll one off a table and drop the other from the same height the balls will hit the ground at the same time.  It is difficult to drop the ball at the moment the other ball rolls off the end of the table, so here is a video of the Mythbusters proving this concept with bullets.

 

Will knowledge of physics help you become a better game artist or computer animator?

 

The answer is YES and for so many reasons!

 

Physics is the branch of science dealing with the properties of matter and energy. It is how we make sense of our universe. Everywhere you see, everything you do and hear can be explained with physics.

 

About 30 years ago, Pac Man was all the rage… It was so exciting to play because you could move Mr. Pac Man left, right, up and down and collect small blue dots and compete for the highest score.  A few years later, 2-D platform games like Mario became much more popular. What made Mario such a big deal? Why was Mario so fun to play? THE ANSWER IS PHYSICS! There was so much more to do because gravity was added. Mario could walk, run, crouch, jump, and fly.  This variety of movement is so appealing to gamers.  Games have continued to change a lot in the past decade while gamers are continuously demanding more. One of the major transformations of games was moving from 2-D to 3-D. Because of this, games today can be much more realistic and similar to our world, but this realism comes at a price; more physics. Just because a game is behaving with the same laws of physics that we do in real life, doesn’t mean that it can’t be imaginative.  A developer may change the value of gravity, or replace the water in the ocean with mercury, but the game is still going to follow the laws of physics we know today.

 

Whether you are modeling, rigging, animating or doing some sort of visual effect for a game or a movie, physics is sure to be a major component of your work. Employers value their employees that have a solid understanding of physics because these employees know how to create a plausible scene that won’t break the audiences suspension of disbelief.

 

When game artists have a solid understanding of physics they can apply this vital information to their specialized field to a great effect – here are some examples:

 

Science fiction movies have thrown a great many exposed humans into the vacuum of space, and practically each unfortunate space man experienced a completely different fate from his fellows. In Brian De Palma’s Mission to Mars (2000), the poor astronaut died instantly and bloodlessly, if in a decidedly gray fashion:

Peter Hyams’s Outland (1981) took a more, ahem, dramatic route, treating humans’ bodies a lot like water balloons:

And Paul Verhoeven’s original (and superior) Total Recall (1990) went full-on horrorshow by treating Arnold Schwarzenegger’s face like a squeeze toy .

By contrast, Stanley Kubrick took a rather tame tack in his sci-fi masterpiece, 2001: A Space Odyssey (1968), by having, well, nothing happen to his exposed space traveler:

What gives, Stanley? If sci-fi has taught us diehard space nerds anything, it’s that space is a vacuum, and vacuum + human = giblets. Why did the master filmmaker who brought us unflinching horror in The Shining (1980) and A Clockwork Orange (1971) shy away from a little space gore?

Well, with all apologies to the underrated genius of Paul Verhoeven (who, by the way, earned a master’s degree with a double major in math and physics), the clip from 2001 is the most realistic of the bunch.

Oh? You don’t believe me? Well, brace yourself, because we’re about to lay some science on you. Here’s an actual video of an actual dude in an actual vacuum actually losing pressure in his actual space suit… and, you know, talking about it afterward:

How can this possibly be true, when we know for a fact that huge differences in pressure can cause explosive decompression? In a vacuum, the pressure outside the body is entire orders of magnitude lower than the pressure inside the body, so why didn’t this guy go *splat*?

Well, it turns out your skin and blood vessels are pretty stretchy, and that goes a long way toward counteracting the effects of the vacuum. You still don’t want to hang out there too long — it is, after all, wicked cold, and oh yeah, there’s no air — but a few moments’ exposure won’t turn you into a over-microwaved hot dog.

And if you happen to be a tardigrade, or “water bear” (seriously), you might even kind of dig a little space travel:

The space shuttle, Endeavour, has now reached her age of retirement having served NASA dutifully from May of 1992 to May of 2011. She was the fifth shuttle built by NASA for use in transporting crew and equipment to and from the space station, after the tragic loss of the Challenger shuttle in 1986. Endeavour, due to cost considerations, was built from parts of past shuttles, including Discovery, and Atlantis.1

Following a lengthy tour of the skies of California, Endeavour will finally retire to a permanent home in the California Science Center in Los Angeles. The aerial tour was done so that many in the country got a chance to see the shuttle in the sky one last time before retirement.2 An effort made all the more monumental, as NASA is now out of the business of space shuttle construction, leaving future developments to the private sector.

The air tour over California concluded the shuttle’s cross country trip on the back of a Boeing 747 from the Kennedy Space Center in FL. Once being removed from the back of the commercial airliner, the shuttle will travel to the museum on the streets on Los Angeles on October 12th and 13th.3

This last hoorah of the space shuttle will be one to remember, so take the time to look to the skies or view the webcast by the Los Angeles Times, to not miss the momentous occasion. I know that I look forward to visiting the Shuttle in her new home in Los Angeles, I hope that you do too.

–Sommer

Getting up into space is expensive and difficult. Think about it. Some of it comes to mind quickly, tons of fuel, expensive rockets, a huge launch crew. But there is more:

someone has to recover the rocket boosters

replace the heat shield tiles after every launch

transport and store all that fuel

many years of training for the pilots

the weather has to be right

refurbish all the rocket parts

very inefficient energy use

and on and on and on…

Currently, it costs about $10,000 per pound to get something into orbit! That cost is for low Earth orbit, which is the cheapest.

All the above is to show you that our method for getting into space is horribly inefficient and will need to be replaced if we want to have practical space flight.

Technology for flying into orbit is improving, better rockets, lighter systems, and even planes that can fly from the atmosphere into orbit are being worked on right now. But there are even better methods that could be coming over the horizon.

What if we were to build a skyscraper that was 22,000 miles tall. To get into space, all you would have to do is take an elevator ride to the top. This was the idea of Konstantin Tsiolkovsky in 1895. Over the years the form has changed from a tower to a cable suspended from the sky but it was firmly in the realm of science fiction. Like many ideas, it has refused to stay in there.

How high can you jump up? A few feet at most. How high can you climb a rope? 10 ft? 50 ft? If it is not more than you can jump you need to get off you computer now and do some pushups…I will wait.

It is much easier to gain altitude climbing up an object than it is to fly up.

So what is it? It has 4 main parts. A cable, a counterweight, a base, and a climber.  A counterweight is in orbit around the earth outside of geostationary orbit. (the point were an object in orbit stays above the same place on Earth.) A cable extends down from the counterweight to the base on earth. The climber then climbs the cable taking people and cargo into orbit.

This works because of centripetal force, the same thing that keeps water in a bucket when you swing it over your head. As the bucket spins, you have to pull on the rope to keep it moving in a circle (It wants to move in a straight line from inertia) If you pull on the rope too hard the bucket will move toward you. If you don’t pull hard enough the bucket will fly away.

The space elevator will work the same way. The Earth is rotating and pulling the cable, swinging it and the counterweight around in a circle. Unlike you, the Earth has enough mass to have gravity. If the balancing act is done correctly the force of gravity on the cable and counterweight will be the same as the force needed to keep the cable/weight moving in a circle so the Earth does not even need to be attached to the cable!

This is what a Nano-tube looks like. Each sphere is one carbon atom.

The hardest part of the elevator is the cable. The material has to be strong enough to hold up thousands of miles of itself. Think about it. If you have a rope hanging off a cliff, the top of the rope has to hold up the weight of all the rope hanging below it. It was only recently that a material that might be strong enough was created. The material is carbon nano-tubes or a similar material called graphene. These are made from carbon sheets. While they seem to be strong enough to make the cable, we currently don’t have the technology or know-how to create long cables of the material.

The counter weight is easy. It can be anything. Most likely this object will be a space station and dock for trips to and from the elevator.

The base station could also take many forms. While the cable could be designed so it did not need to be attached to anything, it would be easier to have it attached to an anchor. Several forms have been proposed. Some are stationary bases that would act like an airport for people traveling into space. Others have proposed that the base station should be a large ship. This would allow the elevator to move to dodge bad weather and space debris.

 

This is one artist’s concept of a climber

The last piece is the climber that goes up the cable. It could also take many forms depending on if it was carrying cargo or people. Energy would most likely be sent to the climber through the cable or by using lasers to send energy. It would also need to carry anything the passengers would need for the trip. This would include an air supply and food. Even if the climber gets moving at 200 mph the trip to geostationary would take 4.5 days. We will have to develop better elevator music!

Dr. Michio Kaku Explains the Space Elevator

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We still have a lot of work to do before this can become a reality, but it seems like it is coming.  A company in Japan says that they want to build one by 2050 and several others are also working on it, such as Google. There are also several prizes being offered for those who can develop technology for the elevator.

Will we be able to climb into space someday? No one knows for sure, but it is clear that mankind wants to move into outer space so something must be created to make it easier.  Maybe in your lifetime you will say ”Will you please hit the geo orbit button for me?”

 

–Jay Murphree

Your senses can be tricked.  You might think you’re looking at a large, yellow, bird-like object, but that is only true if the right color of light is shining on it.

 

You’ll learn about the electromagnetic spectrum in the last week of class.  Visible light is a very small part of the electromagnetic spectrum even though it contains all the frequencies of light you can see.  Most light bulbs are clear or white and give off white light, but you can buy colored light bulbs or gels you can put over lights to change this.  White light is actually all the colors of light, the combination of multiple frequencies, so that clear light bulb is actually giving off every color of light.  A colored light bulb will only let one frequency of light through.

 

So why does that large, yellow, bird-like object appear yellow?  Pigment works by absorbing certain frequencies and reflecting others.  The object appears yellow under white light because the frequencies that were reflected combine into yellow light.  The object absorbs the complementary frequency, blue light.  The truth about this object is not that it is yellow, but that it absorbs the blue frequency of light.  The object will not always appear yellow, but it will always absorb the blue frequency.

 

Imagine this yellow object in a pure white room with white light shining in the room.  Now, cover all the light bulbs with cyan gels.  Cyan is the color combination of green and blue light.  The object absorbs the blue light and reflects the green light.  The room will look cyan and the object will be green instead of yellow.

 

Why does this matter?  If you are lighting a stage, the color of the lights can dramatically change what the audience sees and the mood of the production.  If you are animating a world, you need to know how to realistically create it.  If you are solving a crime that took place in the middle of the night, you need to know if the streetlight affected the witness’s description of the car.  If you want to amaze your friends, you can change their clothes without removing them.

 

So the next time you see a large, yellow, bird-like object remember it’s only yellow because of the lights.