A scientific fact/tidbit you recently learned that you thought was interesting

arthwollipot said:
It is known that the atlatl was invented independently in many different areas of the world very early in human development.
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Yes, I was mentioning that and then for some reason edited and forgot to put it back in! As you say, and Planigale elaborates, this is a fascinating bit of anthropological lore, and a bit of a tale of how complexity emerges. We start out throwing and running, and next thing you know, we're flying into outer space.
 
Cosmic Yak said:
May I present the Detaching Penis Spider, for your edification?
www.livescience.com

Spider's Detachable Penis Finishes Without Him

Some males in cannibalistic species have detachable genitalia, which break off after mating. This means they can only mate once or twice, but researchers have discovered that the sex organ keeps transferring sperm into the female even after it is no longe
www.livescience.com www.livescience.com

It leaves its thingy in the female, possibly to stop other males mating with her, or maybe to stop her killing and eating him, a distressingly common habit among invertebrates. Either way, you have to wonder about the very first male spider to do this. He must have had balls- but not much else!
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Some male spiders bind the female with webbing also.
 
I think we should pitch a reboot of the Fifty Shades of Grey franchise, but with spiders this time.
 
Pixel42 said:
Sadly Richard Attenborough died in 2014. He was 90, so he had a good innings. His brother David is doing even better, though, 99 and counting. :)
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Yeah, wrong Attenborough. Hasty post, too late to edit honestly, and it was of course just a typo not a real mistake, so I will just pretend. I don't know what you're talking about. One of my assistants wrote it, but he's not available right now. He went out for coffee.
 
bruto said:
Yeah, wrong Attenborough. Hasty post, too late to edit honestly, and it was of course just a typo not a real mistake, so I will just pretend. I don't know what you're talking about. One of my assistants wrote it, but he's not available right now. He went out for coffee.
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And never came back?
 
Steve said:
And never came back?
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Who never came back? I never met the guy!

Cut me some slack, I'm trumping as hard as I can, but it's an acquired art I think.

By the way, noting your location, if you think my mixup of Attenboroughs is stupid, just before the previous Trump administration, I decided to donate my land in Nova Scotia to the Nature Conservancy. Back in 1969, when very young, I inherited a little money from a great aunt, and decided to spend the whole 5000 dollars on a nice piece of land. For 5500 Canadian, I got 130 acres in Pugwash Junction, with frontage on a tidal creek, road frontage, a 30 acre woodlot...I thought of moving up there, but other priorities intruded, and in the intervening years the house burned down, but still, talk about bad timing!
 
I find Brian Cox to be a wonderful explainer of physics. Here he discusses the Planck length and related matters:


I don't know if that sounds interesting to you or not, but I found it fascinating. It won't embed in the thread but well worth clicking through, imo. Roughly 20 minutes in length.
 
I haven't watched it (yet - it's in my feed) but the existence of the Planck length may be the thing that prevents general relativity and quantum mechanics from being mutually inconsistent. If there's a minimum size that something can be, you can't have a singularity - which is defined as a point of zero size and infinite density, and which causes all the problems.
 
arthwollipot said:
I haven't watched it (yet - it's in my feed) but the existence of the Planck length may be the thing that prevents general relativity and quantum mechanics from being mutually inconsistent. If there's a minimum size that something can be, you can't have a singularity - which is defined as a point of zero size and infinite density, and which causes all the problems.
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So what is at the center of a black hole? I have been told that it is something with infinite density, but that cannot be correct. You cannot know the exact position of any particle. Hence Hawking radiation.
 
arthwollipot said:
I haven't watched it (yet - it's in my feed) but the existence of the Planck length may be the thing that prevents general relativity and quantum mechanics from being mutually inconsistent. If there's a minimum size that something can be, you can't have a singularity - which is defined as a point of zero size and infinite density, and which causes all the problems.
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I figure it's because they're both models, therefore neither is a completely accurate representation of reality. I don't think they ever will.
 
rjh01 said:
So what is at the center of a black hole? I have been told that it is something with infinite density, but that cannot be correct. You cannot know the exact position of any particle. Hence Hawking radiation.
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Exactly. A singularity cannot exist. It is a physical absurdity. So nobody really knows what is at the centre of a black hole. The existence of a Planck length forces whatever is there to have some spatial extent, though very very small.
 
rjh01 said:
So what is at the center of a black hole? I have been told that it is something with infinite density, but that cannot be correct. You cannot know the exact position of any particle. Hence Hawking radiation.
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Darat said:
We don't know - Hawkins jokingly said it's where physicists breakdown.
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arthwollipot said:
Exactly. A singularity cannot exist. It is a physical absurdity. So nobody really knows what is at the centre of a black hole. The existence of a Planck length forces whatever is there to have some spatial extent, though very very small.
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I think one interesting idea is that there's actually a whole new universe inside a black hole. This also sounds absurd on the face of it, but I don't think we can rule it out entirely. Another "singularity" is the Big Bang itself. What was that? What existed before it and what precipitated it? Perhaps when a new black hole is formed, there is a corresponding "Big Bang" for a new universe on the other side?
 
So, if a black hole contains another universe, and matter is still being pulled into the black hole and converted to energy, is that inflowing energy perhaps what drives the expansion of our universe? Just speculation, I am not a physicist, nor do I play one on TV.
 
shemp said:
So, if a black hole contains another universe, and matter is still being pulled into the black hole and converted to energy, is that inflowing energy perhaps what drives the expansion of our universe? Just speculation, I am not a physicist, nor do I play one on TV.
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It's a good question and one that I've had myself. But I am not a physicist either.
But think about this: Supposedly immediately after the Big Bang, there was a brief period called "Inflation" during which the early universe is supposed to have expanded very rapidly, much faster than it does today. Could this brief era of Inflation correspond to the initial collapse or formation of a black hole, and the expansion we see now corresponds to more gradual feeding as comparatively smaller amounts of matter continue to be sucked in?
Recent findings seem to indicate that the rate of expansion of the universe (and "dark energy", whatever that is; nobody seems to know) may vary over time:
theconversation.com

Dark energy: could the mysterious force seen as constant actually vary over cosmic time?

If dark energy isn’t constant, we may need to rewrite the standard model of cosmology.
theconversation.com theconversation.com

Over the life of a black hole, at any given time different amounts of matter may be falling into the black hole, sometimes more, sometimes less. Could that correspond to varying rates of the "cosmological constant" (i.e. dark energy, and "constant" may be a misnomer) on the daughter universe on the inside of the black hole?

Of course, I might be wildly off, but I have these thoughts.
 
I thought that this was pretty interesting. It's mainly about how fish evolved into animals that could survive, and thrive, on the land, and what kind of new body parts they needed to do it.

 
arthwollipot said:
Exactly. A singularity cannot exist. It is a physical absurdity. So nobody really knows what is at the centre of a black hole. The existence of a Planck length forces whatever is there to have some spatial extent, though very very small.
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Doesn't the fact black holes come in different sizes suggest they don't have singularities at their centers?
 
My favorite new fact is all the galaxies and black holes that the JWST has found means we should all drop the Big Bang theory and start again. Doesn't mean people won't come back to the Big Bang theory after fitting all the new discoveries into the theory. But if you look at history of things like the cause cholera and stomach ulcers, look at plate tectonics, all these things and there are more took a decade or more longer after the evidence was developed before these theories were generally accepted.

Scientists were and are indoctrinated to believe whatever the preexisting theory was at the time and it resulted in difficulty unlearning the old and learning the new to replace it. We are a tenacious species. This is not to say certainty of existing theories is a bad thing, only that we would do better to recognize when those current facts are challenged.

I have one hypothesis though I don't know enough astronomy than to suggest it. Maybe when the Universe first expanded it was a lot more uneven than thought and the galaxies and black holes that formed earlier than they should have were due to these blobs of matter. The plasma still expanded as we observed.

Another idea is that we are seeing the other side of our Universe as we wrapped around it.

And of course we could be seeing another Universe that bumped into ours which is why the galaxies and black holes look to be close to the initial Universe expansion but not before it. They've nudged us. Could be that nudge delivered the missing energy of the initial expansion.

This is fun.
 
rjh01 said:
I do not see why this should be so. The different sizes exist because of their different mass.
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That's right. And strictly speaking a black hole doesn't have size, what you're looking at is the distance from the centre at which light can no longer escape - the event horizon. If you were up close to one (and could somehow survive) you wouldn't see any thing there - it's just an area of space with a huge gravitational curve.
 
The Great Zaganza said:
a singularity is something that happens at some point in the future of a Black Hole - none exit now.
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Because of time dilation in the extremely strong gravitational field, we can never get to that future. At infinite density, time runs infinitely slowly.

Another of the absurdities of the singularity.
 
arthwollipot said:
Because of time dilation in the extremely strong gravitational field, we can never get to that future. At infinite density, time runs infinitely slowly.

Another of the absurdities of the singularity.
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This is not correct. There may have been some very small black holes created at the beginning of time. These would have evaporated by now leaving a singularity behind. How it could be detected I have no idea.
 
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