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efreysson
03-26-2016, 10:51 AM
I'm trying my hand at space opera, and yes, I know the genre requires quite a lot of handwaving, but I want to be able to mention a number and have it make some amount of sense.

I have plasma cannons as the main space battle weapon, backed up missiles. Apparently, Star Wars turbolasers officially inflict about 200 gigatons of force. Is that an absurd number to compare to? Could someone put that into context for me?

Cyia
03-26-2016, 11:05 AM
Tsar Bomba, the mother of all H-bombs, had a yield of 50 Megatons.

1 Gigaton = 1000 Megatons, so Tsar Bomba had a yield of about 0.05 gigatons.

Wikipedia cites Tsar Bomba as:
1,350–1,570 times the combined energy of the bombs that destroyed Hiroshima and Nagasaki (https://en.wikipedia.org/wiki/Atomic_bombings_of_Hiroshima_and_Nagasaki),[9] (https://en.wikipedia.org/wiki/Tsar_Bomba#cite_note-9) 10 times the combined energy of all the conventional explosives used in World War II, one quarter of the estimated yield of the 1883 eruption of Krakatoa (https://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa), and 10% of the combined yield of all nuclear tests to date.

In more visual terms:
The fireball reached nearly as high as the altitude of the release plane and was visible at almost 1,000 kilometres (620 mi) away from where it ascended. The mushroom cloud (https://en.wikipedia.org/wiki/Mushroom_cloud) was about 64 kilometres (40 mi) high (over seven times the height of Mount Everest (https://en.wikipedia.org/wiki/Mount_Everest)), which meant that the cloud was above the stratosphere (https://en.wikipedia.org/wiki/Stratosphere) and well inside the mesosphere (https://en.wikipedia.org/wiki/Mesosphere) when it peaked. The cap of the mushroom cloud had a peak width of 95 kilometres (59 mi) and its base was 40 kilometres (25 mi) wide.

This thing leveled houses for hundreds of miles and shattered windows all the way to Scandinavia. They actually had to lessen its payload because giving it any greater power would have destroyed the bomber dropping it.

You're talking about something hundreds of times that size.

efreysson
03-26-2016, 11:29 AM
Sooo the Star Wars folks didn't do the math, I guess.

GeorgeK
03-26-2016, 12:45 PM
How much energy is that?

It's a Zikawatt Blaster you moron!

What's a Zikawatt?

Big enough to tear them a new one, now shoot the freakers!


point being, new tech means new terms and you don't necessarily need to define the terms as long as you are internally consistent

efreysson
03-26-2016, 01:06 PM
How much energy is that?

It's a Zikawatt Blaster you moron!

What's a Zikawatt?

Big enough to tear them a new one, now shoot the freakers!


point being, new tech means new terms and you don't necessarily need to define the terms as long as you are internally consistent

Well, that is a good point.

King Neptune
03-26-2016, 06:13 PM
On the other hand, how would they be able to produce that much energy and direct it in some way? A smaller and precisely directed amount of energy would be more likely to produce the desired effect, unless you are trying to destroy a medium sized star.

Dennis E. Taylor
03-26-2016, 06:24 PM
GeorgeK tangentially brings up a good point. It makes more sense to rate a beam weapon in megajoules or gigajoules (or even terajoules) rather than megatons. Megatons is a measure of comparison to the explosive power of TNT, and your beam weapon doesn't necessarily explode things (unless it does). Using a laser as an example, it is heating the target and melting or burning it. Or you could use megawatts.

morngnstar
03-26-2016, 07:32 PM
Angry Guy is right, although there is another interpretation of gigatons of force besides tons of TNT equivalent. If we assume turbolasers are actually lasers and shoot light, light has momentum and can impart force. In particular force is the rate of momentum transfer over time. By the quantum equation E = pc, the energy of light is its momentum (p) times the speed of light. If we take the rate over time of both sides of that equation, the left side becomes power (rate of energy transfer), and the right side becomes force (rate of momentum transfer) times the speed of light.

If we assume gigaton = a billion metric tons = a trillion kilograms = 9.8 trillion Newtons based on defining the kilogram as a unit of force by its weight on Earth, then 200 gigatons = 1.96 quadrillion = 1.96 x 10^15 Newtons of force. To impart that much force with light would take 5.88 x 10^23 Watts of power = half a trillion trillion Watts. For comparison that's 50 billion times the average rate of energy output of all the technology on Earth, though only 1/1000 the rate of energy output of the sun.

Short story, Star Wars pulled a ridiculous number out of their ass, and you can too.

Dennis E. Taylor
03-26-2016, 08:32 PM
Or you can make up your own rating, and not define it. "That's a fifty-Schwarzenegger blaster. No shield is going to stop that!"

leifwright
03-26-2016, 08:53 PM
I have a good friend and aspiring writer who is a physicist.

I can ask him a question or two if you want.

Cyia
03-26-2016, 10:08 PM
Or, you could go with 1.21 gigawatts! :greenie

https://www.youtube.com/watch?v=I5cYgRnfFDA