At some point, whether you're involved in big discussions in your job, or your life, or just contemplating things like the stuff you hear about big news events, like global warming, comet 3I-Atlas or anything you have to ask the big question. It's a question that's hardly ever asked, which is a shame because it's important everywhere and for all time.
How do you know what you think you know? I assume if you're reading stuff like this you've heard the old line that "when you assume something you make an ass out of you and me." Considering how few people want to be made an ass of, there sure is a lot assuming going on.
In even the "hardest hard sciences" there are stacked assumptions that aren't obvious to the vast majority of us. How do we know the speed of light? We can (and do) measure that. That can be done in a well-equipped laboratory. How do we know the distances to nearby stars, those within "a few" light years? That's more complex but let me jump around that to something that's more fundamental. How do we know how far away another galaxy is? The technique is based on the observation that certain stars vary in brightness over time in such a predictable way that the maximum brightness they will show is the same absolute brightness (in astronomy that's called the star's magnitude). That's saying if you had a sample of those stars, they're all the same magnitude when they're at their brightest. Since the decrease in brightness with distance is constant, the period of the star tells you how bright the light was when it left there and the magnitude at our observatories tells you how much brightness made it here, which tells you the distance.
The assumption buried in there is the laws of nature are the same everywhere, and that's perhaps the biggest assumption there can be. I'm not saying those laws aren't absolutely the same, I'm saying we have no way of knowing that because we can only measure them in this neighborhood. We assume they're the same because it's convenient. There's nothing we could say to answer so many fundamental questions people have. For example, we constantly see things like how far to some galaxy or the size of the universe or all kinds of things. If those laws aren't absolutely the same all of those headlines are meaningless.
Since I did the well-received post about Comet 3I-Atlas last Monday (Oct. 27), let me drag out a point or two from that. One of the arguments about this one is that it has abnormally large amounts of nickel in it, compared to the iron/nickel (Fe/Ni) ratios we're used to. They're saying because it's a comet, every comet should have the same Fe/Ni ratio or it has been changed by some sort of intelligent process. That's assuming every star system everywhere has the exact same elements in the exact same proportions and I see no reason to expect that. Same elements? They're the only ones we know that exist. Same proportions depends on too many factors. High nickel space rocks exist and are often the source of the biggest deposits of the metal here on Earth. But they bounce around in space, some hitting the planets, some never hitting one. The amount of any mineral should vary.
A topic I've seen talked about since I was about 15 is the red giant star Betelgeuse in the constellation Orion going Supernova "any day now." Since I'm not sure of when I first read nervous stories about this happening, I'll just say it was in 1970 as a "close enough" disclaimer. Close enough to say the star going supernova has been "any day now" for nearly 56 years.
The main thing I remember from reading about Betelgeuse going supernova back then, is that it would be such an incredible disaster there'd be horrible things happening all over Earth. I don't know anything about this girl's videos (TheSpaceChick on this story) but it's the best thing I've bothered to watch. I've seen people talking about this happening on some very specific date in something like next March. SpaceChick's version is the astronomical community says it could blow somewhere between 100,000 and a million years, which in cosmic terms is like tomorrow, while in human time it's more like never.
Without going too far down the global warming/climate cataclysm road, that stuff is based on so many models with entirely PFA (Pulled From Ass) justifications that it's nearly impossible to summarize.
If there's any takeaway from this it's to be aware that even the best "hard science" has many assumptions tied to it. The best thing to talk about are things that can be measured accurately in a small lab. If you can do it yourself on equipment you trust, all the better. Want to measure the speed of light? You need a bright light, a long distance and spinning octagonal mirrors.
