Years ago, I read a book titled “The Science in Science Fiction”, which was disillusioning in many ways–pointing out problems with antigravity, warp drives, and so on. There was a part in it, though, in the chapter on sci-fi weaponry, mentioning that a laser pumped in the gamma range of the spectrum, would be the closest thing to a true death ray one could conceivably build. It mentioned that a gamma-ray laser, in high gigawatts range, could be fired at the sun from a range of several light-days and cause it to go nova. From a purely layman’s grasp of physics, this certainly seems plausible–the laser is putting a great deal of extra energy into a very localized part of the sun, and thus explosively tipping the balance between radiation of energy and its gravity.
This idea intrigued me. “Mankind has always dreamed of putting out the sun, but I shall do the next best thing!” quoth Monty Burns, but I don’t want to settle for the next best thing! Assume I have access to the kind of magical technology that can pump an arbitrarily powerful gamma-ray laser (or in x-rays, if it turns out that you don’t need quite that much frequency). Just how high up do I need to turn its power to make Sol go boom? I don’t even need to do so from lightdays out–how about from, say, 1 AU?
Maybe somebody should actually answer the question.
I don’t think that will work.
First, the Sun cannot go nova. A nova happens on a completely different type of star, a white dwarf. They are very small and dense. Matter from an orbiting normal star falls on the dwarf, where it piles up and then flash fuses. We see that flash as a sudden brightening, a nova. If a lot of matter piles up, the ensuing explosion can rip the star apart. That’s a supernova. Ouch. But either way, the Sun ain’t walking that path.
Second, the Sun is like a huge thermostat: if it heats up, the outer layers would swell, reducing the amount of energy per square centimeter on the surface. Once the extra energy is drained off, it would contract back down. So if you beamed that energy in, all that would happen is you would puff up the Sun a little bit.
Third, the Sun puts out about 4 x 10[sup]33[/sup] ergs per second of energy. For comparison, a 1 megaton explosion is about 4 x 10[sup]22[/sup] ergs, so the Sun puts out the equivalent of 100 billion megaton bombs every second. If you have a laser big enough to affect the Sun, blowing up the Sun is the least of your problems.
What would happen if the sun was hit by an EXTREMELY high-energy projectile, like a largish asteroid traveling at better than .9 C? That probably wouldn’t destroy the sun, but I bet it would do things to it that might wipe out most of the life on Earth.
Scary thing is that you could probably do something like that a long time before you could actually visit another solar system, and it might be the wisest thing to do - let’s say it’s 2100 and we have the technology to make neighboring stars explode or at least get seriously unstable. We hear primitive radio signals of obvious intelligent origin coming from a nearby star system. You know that in 200 years or possibly less they will be aware of our presence and will be capable of snuffing us out. Do you want to give them a chance? Aside from sympathy for a totally alien form of life, what reason would there be to NOT send an asteroid hurtling into their sun before they have the chance to do the same to us?
Even if you could cause some sort of event with a high-speed asteroid (and an asteroid at .9 c is a heck of a lot of energy for us to try to scrounge up), such an event would probably be rather short in duration and directional. You’d have a decent chance of not affecting the planet at all… And then what?
