First, that video was awesome. I guess I should leave it at that, but...

I really was hoping to study physics-math long enough to come up with a formula for this idea of mine, who doesn't want to be famous, right? But even Khan Academy is not going to be able to make me a smart enough mathematician for this, so I'm just going to blurt it out, incomplete as it is. (But if anyone smart can solve the math, and if no one finds dark matter or dark energy, well, don't forget me, okay? I came up with a solution. (Yes, I am proud to be Dunning-Kruger affected.)

Who needs dark matter or dark energy to stretch the expanding universe? As Albert Einstein showed us, gravity warps space time, it pulls it. Pinch a flat and flexible grid from underneath and pull down a little and, viola, you have a model of gravity bending space/time, pulling it. Why give up that easy to understand model? Why add “dark energy” and “dark matter” that perceivable by definition? Who needs dark anything? Why not consider “gravity,” the known and currently measurable effects of gravity, as half of a sine wave? The heavy half. In this video, the force of the spring that pulls down?
https://www.khanacademy.org/science/physics/oscillatory-motion/harmonic-motion/v/introduction-to-harmonic-motion
But where is the other half of the curve? It's in the fabric of space itself stretching! Where does it appear to stretch the most? Between galaxies. Where does it seem to stretch the least, in solar and planetary systems. But maybe it is balancing a bit inside spiral galaxies, which is why they look, um, odd. Or maybe the force is strongest at the source. Regardless, if I'm not wrong then this kind of theory should be testable.
So who needs dark matter? Who needs dark energy? What if Einstein was right about gravitational waves stretching space/time? But stretching it like a stream of water that breaks into droplets, creating space in between? Heck, one doesn't even need to imagine water's surface tension as a mathematical model of gravity. Sand works just as well apparently:http://youtu.be/f3_NDAEBtsI

Think of gravity as like stretching a rubber band. The pull is like gravity. But notice how the distance between the two ends of the rubber band grows? Exactly. Who needs dark energy or dark matter to stretch space? Maybe Einstein was closer to the truth than y’all think.

So there you have it. My pet theory. Well, y'all are scientists, or know a few. Prove me wrong.