Friday, 29 January 2016

Wormhole Dynamics: Standing Waves

This is a bit of relatively simple Physics that you've most likely seen before, and has a lot of application in The Real World outside of the lab.

Warning: This may not look like much when it comes to EVE, but it is vital to understand this model of wormholes. Bear with me... it will all make sense soon.

You'll mostly be familiar with a travelling wave, like the gravitational ones we saw last time. These waves appear to move in a certain direction. The peak of the wave looks like it's moving forward.

Standing waves are exactly what they say they are... waves that appear to not propagate forward. The peaks still move up and down, but they're not going anywhere.

This is an example of one. See how it goes up and down but doesn't appear to travel?

Well this is actually what happens when a waves reflection is added to itself.

Imagine that thick black line is a rope, and you're at one end of it. Your flick the rope up and down, creating a little pulse down the rope. If it's not attached to anything, well, that pulse will just kind of disappear when it gets to the end.

However, if you then fix that end to a wall, the pulse will be reflected back at you.

If you keep moving the rope up and down, oscillating it, you will produce a travelling wave down the rope. Nothing you've never done before. Now imagine that the wave you send down the rope is the faint blue line in the image above.

Of course, the wave you send is going to be reflected back, just like the pulse earlier. That wave must travel down the rope just like the one you send. This is shown by the faint red line in the above image.

It turns out that waves that pass through each other just add themselves. So when the peak of the reflected wave meets the peak of the incoming wave, they add to produce a very big peak. If a trough adds to a peak, we end up with nothing happening.

In a standing wave, the peaks are always in the same place, and there are certain areas on the rope where nothing is happening. The stationary points are nodes, and the peak parts are anti-nodes.
This concludes our Physics lesson for today, and in the next post we'll start bringing these ideas together to my happy thought.

If you'd like to see a standing wave, grab yourself a piece of string now, attach it to something and start wiggling it. You should get a standing wave. If you don't have string, the best way to see a standing wave is to go get up on your feet, and go to a mirror. When in front of the mirror, raise your right hand (or left depending on dominance). Then, gently oscillate your hand back on forth. You should see someone doing a standing wave.

... You'd be surprised how many people won't get that.

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