Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The Tunguska Event

slate.com

Post reply on HN
Print view View original

51–60 of 74 posts

Re: The Tunguska Event

#51

Post by JoeAltmaier »

alexandre_m wrote: post #41
JoeAltmaier wrote: post #32

My favorite conspiracy theory on Tunguska: http://www.reformation.org/tesla-and-tunguska.html

The Tunguska+Tesla event is quite fascinating (the whole life of Tesla is actually). People love to make up a lot of theories and conspiracies, it's nothing new. What is particularly worrisome is that Tesla was a very brillant man and that he believed himself to have caused this. From the information that we have, it wasn't a marketing stunt by his entourage. The guy himself was working on this particle-beam for some…

And Tesla did nothing of note from that time onward. Did the suspicion that he was responsible for thousands of deaths, and that he'd invented a weapon too terrible to contemplate, cause him to retreat from his work? Hard to think otherwise.

Re: The Tunguska Event

#52

Post by JoeAltmaier »

greglindahl wrote: post #49
alexandre_m wrote: post #41

Earlier quoted context omitted.

The Tunguska+Tesla event is quite fascinating (the whole life of Tesla is actually). People love to make up a lot of theories and conspiracies, it's nothing new. What is particularly worrisome is that Tesla was a very brillant man and that he believed himself to have caused this. From the information that we have, it wasn't a marketing stunt by his entourage. The guy himself was working on this particle-beam for some…

Extraordinary claims require extraordinary proof. "No one is certain" is not the right way to approach the possibility that Tesla actually caused Tunguska. edit: clarified what "this" means

Its reasonable to speculate on whether Tesla himself believed he'd caused the incident.

Re: The Tunguska Event

#53

Post by grondilu »

NoMoreNicksLeft wrote: post #47
mikeash wrote: post #27

Earlier quoted context omitted.

Reminds me of one of my favorite jokes. The professor is lecturing, and says, "The Sun will grow to be a red giant, destroying all life on Earth in about a billion years...." A distracted student suddenly sits up and cries out, "Oh my god!" The professor says, "What's wrong? A billion years is a long time, you know. Nothing to worry about." The student is visibly relief. "Oh, great! I thought you said a million years…

I strongly suspect that our species is already on its way to inevitable extinction, and much more quickly than a few hundred years. Barring some science fiction scenarios, fertility has dropped below replacement and is of a nature where it never truly rises. Children who grow up in a low-fertility environment learn behaviors and personality traits that encourage and enhance the already-low fertility, and any who are…

Long ago I read "essai de prospective demographique"[1] written by French demographers. They were raising the concerns you mention and were trying to warn the public of a coming "demographic winter". So your point of view is not rare.

That being said, even if a demographic winter would probably have very adverse consequences, as it is not clear how well the industrialized society would fare if the population was drastically reduced, I have hard time picturing how that could lead to the complete extinction of mankind.

There will always be pockets of population with high fertility, at the very least among highly religious communities. Even if as you suggest reproductive behavior is transmitted, that works both ways, and simple natural selection will always, in the end, favor the reproductive behavior that leads to increasing numbers.

Demographic winter is a serious concern, but I can't imagine it leading to a complete extinction.

1. https://books.google.fr/books/about/Essai_de_prospective_d%C...

Re: The Tunguska Event

#54

Post by raattgift »

cr1895 wrote: post #36
goldenkey wrote: post #22

Earlier quoted context omitted.

water is very dampening. tsunamis are from sustained force

It's literally wet! You'll get dampened indeed. Tsunamis are generated by water displacement from e.g. underwater seismic activity or a massive landslide. Wind-driven waves or tides would be driven by sustained forces. Whether or not an asteroid can/has cause(d) a tsunami I don't know.

A sufficiently energetic meteor strike will cause a high enough amplitude wave to qualify as tsunamis (and which therefore would produce destructive effects onshore).

Exact modelling is tricky, but that sort of thing appeals to some geophysicists.

Funny headlines, serious research:

http://news.ucsc.edu/2003/05/355.html http://www.livescience.com/49298-asteroids-causing-tsunamis....

Re: The Tunguska Event

#55

Post by gkya »

grondilu wrote: post #10
amelius wrote: post #5

> Given a long enough time period, there is a nearly 100-percent chance an asteroid large enough to destroy most life on Earth will impact our planet. No worries. Since quantum mechanics dictates that, given enough time, anything can happen, we can also say that given a long enough time period, life will spontaneously reappear.

A more interesting question is : what kind of delay is worth worrying about? I mean, for instance it is known that life will remain possible on Earth for about 500 million years, after which the Sun will be too bright. We don't seriously worry about it, since so many things can happen in half a billion years that it does not make much sense to try to plan or predict anything in such a timeframe. Similarly, I personal…

Once in a million years is not equal to a million years later. If an asteroid hit the earth today, a million years later one could say that the probability of an asteroid hitting earth is once in a million years.

Re: The Tunguska Event

#56

Post by mikeash »

NoMoreNicksLeft wrote: post #47
mikeash wrote: post #27

Earlier quoted context omitted.

Reminds me of one of my favorite jokes. The professor is lecturing, and says, "The Sun will grow to be a red giant, destroying all life on Earth in about a billion years...." A distracted student suddenly sits up and cries out, "Oh my god!" The professor says, "What's wrong? A billion years is a long time, you know. Nothing to worry about." The student is visibly relief. "Oh, great! I thought you said a million years…

I strongly suspect that our species is already on its way to inevitable extinction, and much more quickly than a few hundred years. Barring some science fiction scenarios, fertility has dropped below replacement and is of a nature where it never truly rises. Children who grow up in a low-fertility environment learn behaviors and personality traits that encourage and enhance the already-low fertility, and any who are…

Low fertility doesn't lead to extinction in a few hundred years. Let's say the average is one child per woman (even places like Japan are above this), then it still takes 23 generations to reduce the global population to a thousand people, and a further ten generations to reduce to one.

Use Japan's fertility rate and you can roughly double those numbers.

I also don't see why disagreement has bizarre implications. World fertility rate is still somewhat above replacement, so all you really need is for the populations currently having lots of babies to keep on doing so. And even if the trend continues way downwards, reversal doesn't require weird scenarios where all children suddenly decide to have twice as many children as their parents. If fertility rates go from 1.5 to 2.5 over the course of ten generations, that would do it too.

Nobody really understands why fertility rates drop with wealth, so it's not weird to think that further changes could cause them to increase again, especially in a world with a much lower population than today.

Re: The Tunguska Event

#57

Post by njharman »

elorant wrote: post #9
gaur wrote: post #3

The scaling with meteor size is impressive. A 100 m object will flatten some trees in Siberia. A 10 000 m object will kill 75% percent of all species on the planet (the KT event).

The problem with the latter is that it will cause a nuclear winter. So that 75% will not die instantly but in 2-3 years after the impact. Add an order of magnitude or even half of that and then you have an extinction level event. It could kill organisms even at microbe level.

It wouldn't be a NUCLEAR winter...

Re: The Tunguska Event

#58

Post by raattgift »

mirimir wrote: post #26
gaur wrote: post #3

The scaling with meteor size is impressive. A 100 m object will flatten some trees in Siberia. A 10 000 m object will kill 75% percent of all species on the planet (the KT event).

Velocity matters too. E ~ mv^2 after all. I'm reminded of Killing Star by Charles R. Pellegrino and George Zebrowski. Even without aggressive aliens, stuff falling toward the galaxy's central black hole may get ejected at relativistic velocity. Very unlikely. But we wouldn't see it until it was almost here.

Well, we're getting photons and probably cosmic rays from Sagittarius A, so not that unlikely. :-)

You're right about small mass but macroscopic objects though, since Sag A's rotation is very sub-extremal, its mass is sufficiently high (higher mass means less curvature just outside the horizon), and its accretion structures and jets are sufficiently dim that there is essentially no chance for a rocky object to get any sort of gravity assist, much less to relativistic speeds.

Much smaller black holes are likely sources of "dangerous" gravity assists, but they also usually have accretion structures whose ICS-boosted radiation would probably disintegrate candidate objects.

On the other hand, even a fairly small chunk of rock boosted to near the speed of light would pretty much end Earth. (Time to dig up https://what-if.xkcd.com/1/ :) )

Re: The Tunguska Event

#59

Post by alexandre_m »

greglindahl wrote: post #49
alexandre_m wrote: post #41

Earlier quoted context omitted.

The Tunguska+Tesla event is quite fascinating (the whole life of Tesla is actually). People love to make up a lot of theories and conspiracies, it's nothing new. What is particularly worrisome is that Tesla was a very brillant man and that he believed himself to have caused this. From the information that we have, it wasn't a marketing stunt by his entourage. The guy himself was working on this particle-beam for some…

Extraordinary claims require extraordinary proof. "No one is certain" is not the right way to approach the possibility that Tesla actually caused Tunguska. edit: clarified what "this" means

I don't think it's plausible that Tesla is responsable for it, but we can raise some questions surrounding the event.

Apparently there's still no scientific consensus (is that even possible?) on the Tunguska explosion and NASA seems to acknowledges that.

Taken from: http://science.nasa.gov/science-news/science-at-nasa/2008/30...

"A century later some still debate the cause and come up with different scenarios that could have caused the explosion," said Yeomans"

No remains of the asteroid, no impact crater and the claims from Tesla together is what is fascinating to me.

Re: The Tunguska Event

#60

Post by NoMoreNicksLeft »

mikeash wrote: post #56
NoMoreNicksLeft wrote: post #47

Earlier quoted context omitted.

I strongly suspect that our species is already on its way to inevitable extinction, and much more quickly than a few hundred years. Barring some science fiction scenarios, fertility has dropped below replacement and is of a nature where it never truly rises. Children who grow up in a low-fertility environment learn behaviors and personality traits that encourage and enhance the already-low fertility, and any who are…

Low fertility doesn't lead to extinction in a few hundred years. Let's say the average is one child per woman (even places like Japan are above this), then it still takes 23 generations to reduce the global population to a thousand people, and a further ten generations to reduce to one. Use Japan's fertility rate and you can roughly double those numbers. I also don't see why disagreement has bizarre implications. Wor…

> World fertility rate is still somewhat above replacement,

World fertility is only above replacement because of a few hot spots that have high fertility. As those cultures are converted to something more western-looking, fertility plummets.

You're postulating that, somehow, this will reverse and those places will convert the west to something not-so-western-looking, or that they'll fail to convert.

Both of these seem very unlikely.

Do you see any trends or evidence that either of those will come to pass?

> Low fertility doesn't lead to extinction in a few hundred years. Let's say the average is one child per woman (even places like Japan are above this), then it still takes 23 generations to reduce the global population to a thousand people, and a further ten generations to reduce to one.

It's a compounding effect. When there are only one thousand people, you still expect those who grew up in such an environment will still somehow manage a fertility rate of 1.0?

What will allow you to hit 1.0 and plateau at that for 33 generations?

> Nobody really understands why fertility rates drop with wealth,

That's easy to understand. As individuals can be mentally ill, so can large groups of people be so collectively. And collectively, the world is neurotic.

> so it's not weird to think that further changes could

Yes, miracles will happen.

Post reply on HN