The Tunguska Event • Hacker News Board

Re: The Tunguska Event

#71

Post by nikanj » Tue, Feb 23, 2016, 9:35 PM UTC

plorg wrote: post #40

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.

That's cute, but the statement doesn't even suggest all life would be gone. If I had to guess, "most life on Earth" would be the majority of macrofauna and macroflora. In other words, life would probably still persist in some form (life...finds a way) and would continue evolving.

Killing things that live on the bottom of the ocean is /hard/. A few kilometers of water is an excellent buffer against, well, anything.

Re: The Tunguska Event

#72

Post by norea-armozel » Tue, Feb 23, 2016, 10:04 PM UTC

NoMoreNicksLeft wrote: post #48

bsenftner wrote: post #25

A fun science fiction read is "Singularity" by Bill DeSmedt; the premise is the Tunguska event being a mini-black hole - and it's caught inside the earth, eating it from the inside out.

David Brin did that too. Then an earth goddess showed up, some white guilt about overpopulation and coke can pull tabs. Is the DeSmedt book better?

I would argue it's much better. I don't want to give away too much of the story but it has lots of questions about physics, politics, and alternate history. It's quite a good read.

Re: The Tunguska Event

#73

Post by raattgift » Wed, Feb 24, 2016, 12:09 AM UTC

mirimir wrote: post #66

raattgift wrote: post #58

Earlier quoted context omitted.

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…

Yes, I get that Sag A is pretty quiet. But there was an X-ray flash about 60 years ago, based on echos seen in Chandra images. Also, there is this: http://www.space.com/19748-hypervelocity-stars-milky-way.htm... The impact description in Killing Star is similar to xkcd's, for what it's worth.

"up to 2 million miles per hour" is pretty slow compared to the speed of light :-)

These stars are in Kepler orbits so the speed tells us the relationship between their mass and the central mass. We can also use their periastrons to trace out the minimal radius of the central mass. Whatever's there is almost certainly a supermassive black hole. Gas or dust or a swarm of smaller black holes in the same radius would undergo gravitational collapse (and light up LIGO! and probably put out a lot of electomagnetic radiation too... but Sag A* is not very bright).

The UCLA Galactic Centre Group has a bunch of cool information about this sort of thing. You might enjoy:

http://www.galacticcenter.astro.ucla.edu/animations.html

Re: The Tunguska Event

#74

Post by alexandre_m » Wed, Feb 24, 2016, 4:17 AM UTC

JoeAltmaier wrote: post #64

krapp wrote: post #62

Earlier quoted context omitted.

This site[0] appears to provide a referenced timeline and breakdown of the feasibility of Tesla's particle beam weapon. The author's conclusion seems to be that, while the principle may be sound (particle beams do exist), in actual practice the energy required to meet Tesla's claims would be infeasible even in the modern era - and certainly would have been impossible in Tesla's day. However, The "death ray" proper on…

I'm wondering if Tesla's equipment may have provided a standing wave to ground the ionosphere or some such technobabble. Certainly he didn't wield the power to make such a blast. But the Earth has powers that large. And Yeah Mythbusters. They 'busted' the myth than you can start a fire using a stick and a bow. Yet my Boy Scouts do this for fun all the time.

I think this is the key element here.

Tesla's whole idea since the beginning was to harness the earth energy itself to produce and power his invention.

Now, did he really find a way to do this more than 100 years ago?

I love to dream that there's that much energy just lying beneath our feet and all around us waiting to be used.