Slashdot Mirror
Sorry, But Lasers Aren't Taking You To Mars Anytime Soon
An anonymous reader writes: It's long been a dream of humanity to travel interplanetary distances at great speeds, or to make it to another star system within a human lifetime. Until recently, technologies to get us there — antimatter propulsion, wormholes or warp drive — have all been composed of physically unrealistic solutions. But recent developments in laser technology make directed energy propulsion a feasible solution. By building a giant laser array in space and developing a new type of solar sail that reflects the laser light with incredible efficiency, a laser sail, this propulsion system is scalable to arbitrarily large powers. There are many technical obstacles to be overcome, and so it's unlikely we'll see the fruit of this anytime in the next few decades (despite the promises of some), but this may well be the technology that takes us to the stars in the coming centuries.
Lasers would get me to Mars faster than I would click on a Forbes link.
Seven puppies were harmed during the making of this post.
Another Ethan Siegel blogspam that will take you to Forbes which HAS BEEN KNOWN TO deliver malware via their adserver. Do not follow the Forbes link!
Tacking works because of the reaction of the keel on the sea water. Unfortunately, there is no sea water in space.
Your link is to a nuclear powered ramjet. Ramjets are air breathing engines and, unless I have been seriously misled, there is a shortage of air between here and Mars. You're probably thinking of nuclear thermal rockets.
I am TheRaven on Soylent News
The truth of mathematics is NOT the truth of reality, so don't try proving the contrary. Mathematics is extremely useful in modeling reality, and, significantly in this case, providing a handy way to come up with consequences of a theory. If we can't get consequences out of a theory, we can't do science, because we can't perform experiments and/or observations to distinguish one theory from another.
2+2 == 4 not because of some fundamental principle of the Universe, but because that's how we've defined integers. You can find lots of physical cases where you take two X, add another two X, and don't get four X. Suppose you have two droplets of water on a rubber sheet. Drop another two droplets onto the sheet. You can get quite a few different numbers of droplets on the sheet that way, depending on where you drop the water and what happens next. Perhaps they combine with the previous two and form one large droplet. Perhaps they splash on impact and we've got dozens. We don't have a law of conservation of droplets. We do have a law of conservation of mass that works in Newtonian physics, since we've observed that.
Noether's theorem is correct. The Law of Conservation of Momentum does depend on physical laws being invariant throughout space. (Actually, the laws get more complicated when we need to consider relativity, but the basic principles are the same.) It doesn't claim that physical laws don't vary between points in space, and it doesn't claim momentum is conserved, but it does show that the two are related. If momentum is not conserved, then we have to have changes in physical laws from place to place, and that would have consequences that we would almost certainly have observed.
I'm not saying the drive doesn't work. I'm saying that it's going to take a whole lot of evidence to convince people, and I haven't seen a whole lot of evidence.
"When you have eliminated the unacceptable, whatever is left, however improbable, must be the truthiness" - Holmes