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Old 01-21-2021, 07:14 AM   #11
hal
 
Join Date: Aug 2004
Location: Buffalo, New York
Default Re: EMP and water

So theoretically, with the biosphere stripped off the world, we're looking at an uninhabitable world. Space faring nations could inhabit the world as if it were a Moon, but I can't help but wonder if the psychological impact of the survivors of such an event would simply become apathetic overall.

Looks like I'll be modifying my Traveller Universe a little bit more.
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Old 01-21-2021, 11:58 AM   #12
Pomphis
 
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The canonical event was flares, not an eruption of the entire surface. Simply postulate that the flares covered only a few percent of the starīs surface and their radiation went out as beams, which hit the worlds in question but mainly missed Darrian.
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Old 01-21-2021, 01:32 PM   #13
hal
 
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Originally Posted by Pomphis View Post
The canonical event was flares, not an eruption of the entire surface. Simply postulate that the flares covered only a few percent of the starīs surface and their radiation went out as beams, which hit the worlds in question but mainly missed Darrian.
For what you said to be true, that would imply that the event was directional, not hemispherical (ie, capable of affecting entire worlds in multiple directions). Either it was directional and only hurt one world, or it was spherical and affected everything in a radius of effect out to 6 parsecs of actual destruction, and a 7th parsec of interfering with communications and computer memory cores.

Can't have it both ways it seems.
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Old 01-21-2021, 02:49 PM   #14
Pomphis
 
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Originally Posted by hal View Post
For what you said to be true, that would imply that the event was directional, not hemispherical (ie, capable of affecting entire worlds in multiple directions). Either it was directional and only hurt one world, or it was spherical and affected everything in a radius of effect out to 6 parsecs of actual destruction, and a 7th parsec of interfering with communications and computer memory cores.

Can't have it both ways it seems.
Why not? There were flares (plural). Each one could have been directional, but each in a different direction.
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Old 01-21-2021, 02:53 PM   #15
Anaraxes
 
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The description of the event from the Traveller RPG Wiki:
Quote:
Originally Posted by Traveller RPG Wiki
In -925 the Abh project finished construction of its star probe. In -924 the second star probe, with improved shielding, was launched into Tarnis. The probe reached its operating depth of 300,000 km, and the meson communicator indicated an increasing instability in the sun, centered on the probe itself. Tarnis took a slight wobble and began throwing huge stellar flares.

These flares generated a huge electromagnetic pulse that blew all electronic components on Darrian. About three weeks later the physical wave front of expanding gas reached Darrian. When it hit, the last of superheated gases struck like a blowtorch, temporarily raising local temperatures to 250° and higher. The Maghiz destroyed whole areas of Darrian, scalding basins, evaporating shallow seas, burning forests and grasslands, and destroying populated areas. Fortunately, the flares lasted only three days. At the end of those three days, the surviving 20 percent of Darrian's population came out and began rebuilding.

The Abh Project station in the asteroid belt was never shielded for flares of the magnitude that were generated. The station itself was destroyed; most of its personnel were killed. The survivors spent four years repairing a single shuttle that would take them back to Darrian.

The electromagnetic pulse from Tarnis continued through interstellar space at the speed of light, hitting each of the Darrian colony worlds in turn. Even with forewarning, it was an impossible job to adequately shield every piece of electronic equipment from the pulse. As it arrived in each system (which scheduled a Pulse day for equipment to be powered down), some unshielded equipment was fried and some electronic systems failed.

https://wiki.travellerrpg.com/Maghiz
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Old 01-21-2021, 09:51 PM   #16
hal
 
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Why not? There were flares (plural). Each one could have been directional, but each in a different direction.
Traveller's "to hit" modifiers for hitting a given target using light speed weaponry (aka lasers) will give you a hint of sorts. We're talking about hitting worlds with a precision where the distances aren't measured in light seconds, but in light years. Granted, the targets are larger than starships - but those pulses have to hit as a wave capable of engulfing an entire star system to achieve what was described in a role playing source book written in 1987.

No fault to the writers in the sense that they just didn't know - but 30 years later, I'm questioning it via the internet (which didn't exist then) and asking people whose science background is far better than mine (something presumably the writers of the original source book did not have).

If the energy levels capable of an EMP affecting star systems some 6 parsecs away were applied to the world that was 1 AU away - one estimate was that it would vaporize some 6 meters worth of water. I don't know the math, but I trust the poster enough to say "good enough for government work"

It would essentially destroy the biosphere of the world.
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Old 01-21-2021, 09:59 PM   #17
Anthony
 
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Why not? There were flares (plural). Each one could have been directional, but each in a different direction.
And each one aimed straight at another star? Sure, but that's well into 'enemy action' territory.
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Old 01-22-2021, 06:52 AM   #18
Anaraxes
 
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Were the flares in hal's version aimed, and aimed only at stars? The Traveller version isn't deliberate, but an unexpected side effect. Why do to-hit modifiers become relevant?

Last edited by Anaraxes; 01-22-2021 at 06:58 AM.
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Old 01-22-2021, 10:43 AM   #19
Pomphis
 
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And each one aimed straight at another star? Sure, but that's well into 'enemy action' territory.
Who said each one? Some. There may have been hundreds or thousands of flares, a few hit systems in the neighborhood, most hit empty space, and one didnīt hit Darrian directly but missed closely enough to still affect it.

Which also explains why nobody puts much work into building another startrigger. You cannot aim it. Only few percent of the surface flare and emit significant energy, almost all of it goes into empty interstellar space and it is pure random whether a beam hits something and what.
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Old 01-22-2021, 11:54 AM   #20
Polkageist
 
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This is one of those questions that'd be perfect for Bill Nye or Kyle Hill on youtube. Def check out his channel, there's probably something adjacent to this because I know he's talked about stuff like supernovas and gamma ray bursts.

Let's scope out the situation. There's an EMP burst that's capable of disabling electronic devices at 6ly distant. How is this energy transferred to the device? Well, obviously it's a electromagnetic field so we have to think about how that arrives 6ly away. I'm not a physicist, nor a famous youtuber that I want to channel, so I have no idea how or even if a EM field can be projected that far. I do know that other forms of radiation like cosmic rays or gamma rays, or in the case of our own sun big chunks of actual stellar material in the form of flares, can cause em fields in a planet's atmosphere (thx wikipedia!) by ionizing the atmosphere and interacting with the Earth's magnetic field, and that effect then causes a local EM field that could cause problems. I think that's how solar flares cause EM effects on earth, not because the flare itself is directly causing the EM effects, but that its interaction with the Earth generates the effects that we're thinking of and burns out your phone.

The interactions between radiation, electromagnetic fields, and all that stuff is pretty complicated so to answer your original question of 'how well does water protect' is 'it depends'.
If it's ionizing radiation, then the water works pretty well. We all know that it's a great absorber of radation, as dense water gives plenty of opportunity for an energetic particle to smack into something. The problem is that that energy has to go somewhere. In the case of water, that energy may be in the form of heat. In the case of the Earth's atmosphere, it's the form of bright lights of the aurora. Regardless, that energy doesn't just go away, so if it's strong enough to induce an EM field at 6ly, being 1 AU away from that kind of radiation is enough to cook anything including a planet to a cinder. Also, I don't think water stops magnetic fields, so a phone would be just as vulnerable under water as it would be anywhere else. Frickn' magnets.

e: Catching up on the discussion, looks like the back story is that it is in fact a series of solar flares. So it's a solar flare that's big enough that it can cause a strong enough EM field on interacting with a planet 6ly away. The conclusion that a world 1 AU away from said flare (and hit by it) is rendered uninhabitable is probably a charitable conclusion. As you pointed out, 6ly is some 379k times greater distance, and a solar flare that affects our own planet at 1 AU is no slouch. For a flare strong enough to cause the same effects 379 thousand times further away... well, I wouldn't plan on some sunblock cutting it.

e2: Ok, thinking further, how BIG of a flare would it take to do that? I think the answer to that is 'really big', though not quite supernova big. However, it's hard to find any information about stellar events that exist between a solar flare that doesn't spell the end of a star (and thus doesn't really leave the star's immediate neighborhood) and something big enough to reach out light years with notable effects that isn't also a nova. No matter what, you don't want to be nearby when something like that pops off.
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