hyperion

Re: Gravity is gone?

Cancer' date=' would you know enough physics to guess what would happen to a white dwarf, neutron star, or black hole if gravity was turned off for a second or a minute?[/quote']

 

 

My guess would be the same as to a star. Except more. Because you would be dealing with alot more heat due to the absurdly high mass compacted into such a small space.

 

 

(edited to add)

 

Er yes...what Cancer said.

Re: Gravity is gone?

Would the inertia of the solar mass be a factor when the expansion would be happening at a molecular level? I mean those are some abusrdly hot molecules pushing against one another. Without gravities pressure I would imagine the entire mass rapidly expanding fueled by superheated molecules explosively pushing against one another. How much pressure would 15MK of heat have against a object that has its primary binding force removed? I am asking hoping you know, because I don't I am just speculating.

Re: Gravity is gone?

(Cancer puts on his professor hat and hauls out his old ASTR 421 and 422 lecture notes.)

 

The Sun rotates very slowly (about a month rotation period), so let's forget rotation effects for now.

 

Suppose you have a bottle of gas. If you open the bottle, the gas will expand since the confinement is gone. The speed at which it expands is the speed of sound for the gas.

 

The sound speed turns out to be something you can compute fairly easily. The temperature at the solar photosphere is about 5800 Kelvin (there's a range, of course, but that's the standard representative temperature). The photospheric gas differs from air in that it's monatomic, so the ratio of specific heats is 5/3, and the ideal gas law applies. The mean molecular weight for solar gas is about 1.4 (remember, it's ~90% hydrogen by number, ~10% helium, ~<1% other stuff, and the level of ionization in the solar atmosphere is small). The sound speed is just

v = sqrt( gamma * R * T / M )

and that works out to be about 7600 m/second.

 

So in the one second after you let the solar atmosphere out of its bottle by turning gravity off, it will move outward by about 7.6 kilometers. Sounds big, but the solar radius is 700,000 kilometers. From our viewpoint 1.5e+8 km away, we would not even notice. From Earth that subtends about a tenth of an arcsecond. You'd see it using a space observatory, but you can't make out that level of detail from the ground.

 

The thermal timescale for the sun, a/k/a the Kelvin-Helmholtz timescale, is the time it takes to respond, thermally, to changes in its structure. "Thermally" means gas expansion or compression due to temperature changes. That timescale is on the order of ten million years. So messing with the Sun's structure by, say, turning gravity off for a second isn't going to make a lot of change. Turning it back on again has about the same effect. In terms of overall structural change, it isn't going to matter.

 

(If you want to compute the v = g * t impact speeds at the solar surface after your turn gravity back on, the sun's gravity at its photosphere is about 28 times the Earth's gravity at Earth's surface. The impacts are not going to raise the temperatures to the ten million Kelvin temperature regimes -- or cause high enough densities -- to get to the realm where you start fusion on the surface, which is what happens in a nova.)

 

One second is a piddly-*** short time for something as large and massive as a star.

Well I certainly cannot argue with the math since admittedly I am out of my depth. But I have to ask, what about the effects of inertia from the initial expansion? Would gravity, which if I remember correctly as a primary force of nature is extremely weak compared to both thermal and electromagnetic effects.

Also in your computation is the sound speed of gas its expansion in a vacuum?

Your example was using the temperature of the photosphere. What about the Sun's core? Without Gravity to keep the solar mass compressed wouldn't the extremely hot and dense core expand. That would be alot of inertia gravity would have to overcome. I would image a one second expansion of a star's core would generate some incredible energies. Interesting thing to ponder though.

Re: Gravity is gone?

Heat expands. Without gravity to counter the heat generated by the fusion reaction the sun would expand really really fast.

My guess even a one second lapse would be sufficent to upset the balance and start a very, very, violent expansion. Nova.

Re: Polishing The HERO System

I agree with you that a generic system should enable one to build a wide range of characters (alomst anything you can imagine).

 

But to be fair, I don't believe that anybody has suggested changing to a linear system. The change to a different exponenital model would still allow Superman to be created relatively easily (compared to a linear system). If you were to double what a character can lift with every 10 points, a character who currently would be built with 125 STR would need 240 STR under the new system. 240 is quite a bit higher than 125 but at least it is still the same number of digits.

 

 

A 125 STR Hero character would have an 80,000,000 STR in GURPS. (a literal translation to 3rd ed GURPS)

 

 

 

Interestingly enough, I think that simulating the comics is what Hyperion has in mind.

 

The problem is that, in the "offical listings" for the Marvel Universe (which Hyperion has mentioned), the strongest characters pretty much max out at 100 tons, but Hero allows characters to go far beyond this limit. Therefore, Hero does not work in the way that Hyperion expects. So he has rewritten the chart to place 100 tons lift at 100 STR (which if you are going by a chart, would probably the high end). Note: Since I can't read Hyperion's mind, I may be worng about his motivations, but I'd guess that I'm pretty close in this case.

You guessed right hehe. I am getting the feeling this has been discussed before in these forums.

Re: Polishing The HERO System

The Official Handbook of the Marvel Universe uses a scale that is FLATLY CONTRADICTED by the comic books! It was an arbitrary scale they came up with and has little relation to an actual description of what the characters do when it comes to heavy lifting. I have no idea why anybody who has read Marvel Comics would allow a MINI-SERIES dictate the strength of the characters to them.

Because it is the "official" Handbook. And that it is impossible to design a accurate character from the comics. Hero's strengths and abilities fluctuate wildly from writer to writer and year to year. So instead of holding on to a issue you read five years ago as a baseline for the "Things" strength it seems more logical to use what marvel has said is the official strength level. Even if they break thier own rules it is at least what they concieve the character's power level "should" be at.

Re: Polishing The HERO System

Wow DC's system sounds horrible. What I was basing my numbers on for MU characters were those Marvel Encyclpedia issues they came out with in the 80's. About the same time Secret Wars was running.

My interest in comics took a nosedive after that, but I remember they had some hard numbers for lifting ability. If anyone has those issue or knows what I am talking about please ket me know I would love to pick them up again.

Regardless, it seems alot of people are happy with the ways things are and I just wanted to get others opinions on that game mechanic.

Incidenlty, no way Batman can lift 800kgs without pushing. Sorry, not buying it. I would think twice about using a game system like DC heros as Canon for my campaign, sounds like it is made for a younger crowd.

Re: Polishing The HERO System

Even your cherry picking of my list doesn't work for you. Ever read the old Annual where the Thing and Colossus are arm wrestling? The Thing and Colossus aren't supposed to being wildly different in strength. How strong do you think Superman is? Do you think he can just vaporize any other superhero? Based on what I've seen written, including Marvel/DC crossovers, that isn't the way it would go down. And Doc Samson can get plenty strong depending on the writer and his hair length.

 

And Supes is the high end in DC for protagonists. Wonder Woman, J'onn J'onnz, and Captain Atom are all plenty strong but not quite as strong as Supes.

How many dice do you think Superman would throw down?

In my translation without changing the rules: Thing 90 strength, Thor 120 strength (without Odinpower or belt), Superman 130 strength and Batman 25 strength. It looks to me like there is plenty of differentiation between Batman and Superman. Batsy can roll base 5d6 and Superman can roll base 26d6.

Well that explains a big part of our difference of opinion. Using standard STR charts in CHampions I would place Thing at 55 str, Thor 60 str, and Superman 100 str. Remeber with the ability to "Push" they could increase thier lifting power and quadruple the amount they could strain and lift.

A 55 STR thing would place base lifting STR at 50 tons with pushing he could lift 200 tons. A 60 str THor would be 100 tons with pushing could lift 400 tons. And Supes 100 str 25 thousand tons with capability to lift 100 thousand tons. A 100 str in the standard rules is absurdly strong.

According to your examples. Thing could lift 6.4 Thousand tons. Thor, 400 thousand tons. And Superman, in the millions on tons. Not pounds...Tons. Absurd.

Even without pushing. You think The Thing can lift thousanads of tons? He is like a middleweight brick in MU. I think he could break 100 tons lifting if someone life or his own was depending on it, but a normal "deadlift" is well under that.