The original sentence is consistent with the assertion that the mountains had formed before the first boney ancestors of dinosaurs evolved. This is also consistent with the presented timeline.
The correction would mean that the mountains may be older or younger than dinosaurs, because they are only older than bones, and the article is deafeningly silent on the issue of whether dinosaurs had bones.
It’s a failure of literacy on the poster’s part, hence the downvotes.
“The mountains aren’t just older than dinosaurs” implies that they are older than dinosaurs but not not only dinosaurs. But I’d be lying if I said I never skipped words sometimes, so whatever.
It’s a failure of literacy on the poster’s part, hence the downvotes.
But he’s clearly being tongue-in-cheek? Is it time to bring the /s to lemmy?
The other reason I was initially confused, but reading this thread helped, is that by presence of bones in the cave they don’t just mean that there aren’t any bones lying around, brought in by cavemen or bears dying in the cave. They imply that the cave is basically not accessible normally and what would be found in it (bones, fossils etc), if there was anything, can only come from the time when those mountains were formed. I think… Maybe that was obvious for some people.
Maybe, this sentence, out of context. The rest of the post makes it abundantly clear that the ages of these things go:
mountains -> bones -> dinosaurs
The poster may either be a victim of Poe’s Law, in which case their “joke” wasn’t very funny, or they could be making the logical deduction as you describe but as a mistake. I thought it was the latter.
There’s no mistake, he’s just poking fun at the imprecise language used in the article. We all know what the author meant but only because English is more forgiving than math. I’m not saying I was rolling on the floor or anything, but it wasn’t that bad of a joke imo
It’s basically two booleans that don’t go together
Is the mountains older than the dinosaurs = false
Is the mountains older than bones = true
They should both be true, but the writer had the first be false, hence leading to all dinosaurs being boneless. I guess it’s a colloquialism in the English language, otherwise all y’all wouldn’t had downvote the poster for being pedantic
They’d have to lie about who they slept with, and I expect the other person might have something to say about that if it was not true.
I wonder if they verified each claim from both sides.
Edit: it’s a scientific paper, so there’s no need to wonder!
In fig. 2, and in all discussions presented here, all romantic and sexual relationship nominations linking students are included, whether or not the nomination from i to j was reciprocated with a nomination from j to i.
Then it’s certainly mostly bullshit. Male students tend to massively exaggerate when they tell stories about how many sexual relationships they had. Source: I was a male student.
Technically a close-range gamma ray burst can kill coronavirus, but there’s a good reason no one is using it for that purpose: it’s a goddamned close-range gamma ray burst.
openstreetmaps ftw. Get that, turn on cartographic overlays (outdated scans but still useful), aerial imagery, download and import nhd data, pull up ngs website, and enjoy. Help us map rivers! Even better if you can do an actual ground survey w/ gps.
Be sure to check out the osm wiki! For editing, you can use their web viewer, but I personally prefer JOSM for more advanced work. Vespucci is a great tool for mapping on your phone.
btw NHD data tends to be too large for JOSM to handle… my one complaint about JOSM, I feel it could be more memory efficient. Qgis can be used to process and extract large datasets, just split them up into several files per state. (You also need to merge the source files.) But it’s totally worth the pain, because you get a lot of rich, high resolution data.
Depending on where you live, your state or city might also have open datasets available.
I spent way toonlong mapping our houses in my neighborhood. It’s always funny to see my work on apps, I’m like shit that street is missing houses I need to get on it.
yeah, it’s addictive, I started with sidewalks in my neighborhood, and before I knew it, I was mapping parking zones, fire hydrants, trash cans, benches, traffic signals, speed limits, turn lanes…
What’s the best tool to map points? I walk my dog and would love to quickly drop a pin for a sewer grate or fire hydrant? Is there something I can do mobile?
I would also like entomologists to pronounce the insect orders properly. That ‘p’? It belongs to the ‘-ter’. It’s ‘pter’, for wing. As in ‘coleo-ptera’, the ‘shield wing’, not ‘col-e-OP-tera’. Or ‘neuro-ptera’, the ‘lace-wing’, not ‘neur-OP-tera’.
We actually put the accent on a syllable THAT DOESN’T FUCKING EXIST in the Greek.
I’m lurking through posts trying to distract myself because I’m in an overwhelming amount of pain, and this comment of yours just made me actually laugh out loud a bit. Thank you for that! Especially the ‘putting on Groucho Marx glasses to defend your own point pretending to be someone else’ part. That whole situation, and the way you just described it as if it were happening in a bar instead of on a forum, just amuses me way too much. Also, I just accidentally typed “anuses” instead of “amuses,” which also amused me way too much…
Anyway the point of my rambling is you’re fucking funny and I appreciate you, dammit.
Light doesn’t travel the same speed in water or glass as in a vacuum.
In a medium, light usually does not propagate at a speed equal to c; further, different types of light wave will travel at different speeds. The speed at which the individual crests and troughs of a plane wave (a wave filling the whole space, with only one frequency) propagate is called the phase velocity vp. A physical signal with a finite extent (a pulse of light) travels at a different speed. The overall envelope of the pulse travels at the group velocity vg, and its earliest part travels at the front velocity vf.
That's light as an aggregate wave. Photons, actual light, always travel at c. What's happening in a medium is the rapid absorption and readmission of photons. The probability of admission is based on structure of material causing things like lens or mirrors to work.
You can think of it as the photons having to jump between platforms before the can continue running at c.
What’s happening in a medium is the rapid absorption and readmission of photons. […]
You can think of it as the photons having to jump between platforms before the can continue running at c.
That’s an intuitive model, but unfortunately it doesn’t have the advantage of actually being correct. Photons are not being absorbed and reemitted. See here for why: lemmy.world/comment/5444224
That is wrong. Stochastic yes. Photons emission is probabilistic. Destructive interference causes emission to overwhelming follow classical wave theory. Here's a better explanation with a neat graphic.
It sounds like you’re conflating different concepts. A stochastic process like absorption/reemission would blur the light, so that’s not it. And the linked explanation is basically correct (in classical physics at least), but it doesn’t corroborate what you originally claimed as that’s not necessarily requiring absorbing anything. Photons can jiggle the charged particles in glass and get them to make new phase shifted light despite not being absorbed.
But doesn’t relativity explicitly state that c is the speed of light in a vacuum, and travelling through other mediums explicitly changes and is explained by relativity?
Not really no. Special relativity explains the relationship between space and time. General relativity expands on this to account for gravitation.
One of the postulates (i.e. assumptions) of relativity is that the speed of light in vacuum is the same for all observers. But the theory doesn’t actually require any particular value for c, it only needs it to be constant. And it doesn’t explain the behavior of light in a medium at all.
In fact, relativity doesn’t explain the mechanism by which light interacts at all, that is the domain of Quantum Electro Dynamics.
the speed of light expressed in units of distance per time, is a dimensionful quantity so it probably doesn’t mean anything to say some theory does or does not predict a value for it. The value is entirely determined by how big you choose your yardsticks and sundials to be, which is arbitrary convention.
It is only meaningful to talk about theoretical predictions of the values of constants if they are dimensionless, like the fine structure constant.
However relativity does suggest as a natural point of view that space and time are just orthogonal directions in a unified spacetime. In this point of view, relativity gives you the option of measuring your timelike and spacelike coordinates with the same yardstick (which you may still choose arbitrarily). And then relativity does predict its value. It’s 1. No units.
Wow that is so interesting. So am I understanding that relativity explains space, time and gravity’s interactions with one another, while quantum science explains interactions with much smaller objects like matter?
Don't think about individual photons. Think about billions of them with destructive and constructive interference. The probabilities of all the sitting l additive waves of light.
well, if it get reflected and change direction it going to be at light speed, so it can be interpreted (probably incorrectly lol) that it “accelerated instantly to the other direction after the reflection”?
This is an interesting question. Instant acceleration is mathematically implausible, but I don’t know if there’s a better physical interpretation for what happens to a bouncing photon. I’m guessing this is one of those “less particle, more wave” situations where the instantaneous velocity of the photon is undefined.
According to some random internet sources, reflection is the not-quite-instantaneous process of the photon being absorbed and then emitted by the electrons in the mirror.
As a rule, it’s probably best to avoid “random” internet sources on matters of how light works because there’s so much confidently parroted misinformation out there. For example, this is completely wrong: youtu.be/FAivtXJOsiI See here for correct answers to that issue: youtu.be/CiHN0ZWE5bk
The speed of light is different depending on the medium though isn’t it? So to change speed I would have thought some acceleration would have to be involved.
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