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How Stretchy is Space? November 25, 2017

Posted by Sobek in News.
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It’s been a while since I did a long essay kind of post. I’ll probably go back to posting pics of birds soon enough, but for tonight this is what you get: me wondering aloud how stretchy space is.

Year’s ago, my oldest boy wanted to do a science project about black holes. If you’ve studied any physics at all, you’ve probably seen diagrams about how gravity wells work, with the notion that a heavy object will bend space-time and thus distort the path of moving objects, including beams of light.

250px-GravityPotential

Gravity well. Definitely not an inverted nipple, you filthy-minded monkeys. 

His proposed experiment was to measure the distortion of a moving object based on proximity to the center of the well. Oh, by the way, my boy is super crazy smart. So I got to help him with this project, and I built a wooden frame and got some weights and marbles and whatnot. Then I went to the fabric store to get some fabric to stretch over the frame so we could do the experiment and make the measurements. My biggest question was whether the distortion on the rolling object would increase linearly with increased proximity, as opposed to exponentially or something else.

We had fun building the frame, taking the measurements, and finishing up his science project.  I occasionally think about ways we could have improved the project, but for a kid in sixth grade, it was a great experience.

Here’s one thing that stuck with me, though, despite the years. As I was building that frame, I had to pick the best kind of fabric. Something too stretchy would have dropped the whole surface to the floor: everything in the gravity well would have been at the bottom of the gravity well, and every marble roll would have ended up stuck – no data produced.  If the fabric wasn’t stretchy enough, then it would be like rolling a marble across a board – putting the weight in the middle would have no effect. I grabbed a fabric that seemed average in terms of stretchiness and called it good. As long as I used the same fabric for all experiments, the stretchiness was a constant and had no effect on the experiment.

But what if it’s not a constant? I can assume that question away so long as I’m dealing with marbles in my kitchen – I don’t have instruments fine enough to make a difference anyway. But if we’re trying to measure how much Jupiter weighs, or the Milky Way galaxy, then changing stretchiness might be a huge factor.

Here’s a TEDx talk I saw years after my experiment that really got me wondering if i was on to something. Please stick with it: a lot of the ideas seem strange at first, but when he gets into specifics at the end, I find myself thinking, can that possibly be true?

I want to say it’s impossible that the gravitational constant can change — that’s what makes it a constant, after all. But what if he’s right about the data? And if so, then it seems like everything is potentially up in the air, so to speak. Could space be stretchy – but stretchier in some places than in others?

I’ll close by mentioning this old post I wrote, on “sciencism.” The speaker in that YouTube video touches a little bit on a partially formed distinction I had in my brain at the time, between believing in science (as a method of inquiry) and believing in Science (as a body of knowledge wherein we understand the big picture, but just need to work out a few minor details). I suppose you can thank climate scientists for that — I’ve gotten so accustomed over the years to hearing about scientists who assert they have it all figured out, and then admit, oh by the way we don’t understand ocean methane at all so we wrote it out of our equations. In that respect, there was more intellectual rigor happening in my kitchen, in a test devised by a sixth grader, than what routinely influences world governments nowadays, because SCIENCE!

 

Comments»

1. Sobek - November 25, 2017

Long post made shorter: if space stretches in a non-uniform manner, how would we even test for that?

I can do it in my kitchen, with a piece of fabric, by freezing all the other variables and testing different kinds of fabric with the same marble. But I can exactly move Jupiter to somewhere in the Andromeda galaxy and weigh it there.

2. Sobek - November 25, 2017

The xkcd guy, who is really awesome, did this comic that I like a lot:

https://xkcd.com/1489/

But it evidences a humility about science as a body of knowledge that I’m not sure he is always willing to acknowledge. As for example in a lengthy thing he did in AGW:

https://xkcd.com/1732/

Even assuming I trust the data (I don’t, because the climate scientists are so hell-bent on undermining their own credibility), there are at least two extremely glaring flaws in his assimptions:

1. That measuring from the time of the last Ice Age Glaciation is statistically significant, in light of the Earth ‘s age, and

2. That any changes are caused by human activity.

It’s odd to me to see a guy willing to admit he doesn’t understand how gravity works, but still exhibit bullet-proof confidence in climate models that never successfully predict anything.

3. lauraw - November 25, 2017

Yeah, and since the data at temp-measuring stations have been shown to be corrupted by siting the stations near AC exhausts and pavement islands, plus ‘climate scientists’ have been caught altering not only current but historical temperature data, it’s all rubbish, frankly.

Sad.

4. Retired Geezer - November 25, 2017

This may help you:

5. lauraw - November 26, 2017

HAH!

6. Cathy - November 27, 2017

Sobek, I followed your story into the fabric store. Then got distracted by the yard-goods. Kaffe Fassett designs charm me. Was pleased to find more of his designs than I could afford while in a Southern California fabric store last week.

I agree with Laura and Geezer, btw.

Hugs.


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