As of 2021, cars from the 1970s are in short supply.
You are going to all the work of building bunkers and all, you can probably put together a car or two as well.
I don’t know the current state of it, but used to be that most military trucks could run on pretty much anything that burned.
If you go down that road I would rather recommend a vintage agricultural tractor. That runs on anything that burns and will be useful in that hypothetical aftermath. And they are fun to drive!
But I still believe this thread is going in a too optimistic direction. The damage would be too big, our civilisation too fragile.
The discussion about the difficulty of traveling distances involves too much modern thinking and not enough imagination. Gas, diesel, cars, they were not needed or available for thousands of years. People somehow still easily traveled great distances before the modern highway system. Waterways. They predate highways, but the ways part of both words means the same thing, a way to travel.
The Mississippi, the Missouri, the Columbia, the Ohio, and others, can be traveled for hundreds of miles by human powered boat. One of the primary goals of the Corps of Discovery, otherwise known as the Lewis and Clark expedition, was to find a water route across the continent.
Survivors will get around. This whole discussion is too much doom acceptance and too little acknowledgement of properly motivated human ingenuity. Survival is a hell of a motivator.
Waterways are how people got around before, that is how many things still are transported, and they would become a primary method of travel in the post impact era again.
Lewis and Clark were skilled explorers who knew how to make use of the resources they came across in a natural setting. A team of third-millenium mall rats would not fare as well.
A couple of them were, but not all. Most were hired with few references other than being young and strong. Some with hunting skills, all with some kind of outdoor skills but that was the norm for that time. But it was not a group of highly trained individuals like those who would be chosen to go to Mars or something. They were very fortunate or lucky if you prefer that term, but highly trained they were not.
And I would not discount the survival abilities of a group of third-millennium mall rats at all.
Ummm…
In Lewis and Clark’s time, everyone had at least a passing familiarity with growing crops and raising animals. Today, most people don’t have any idea where their food comes from, and would probably water their crops with Brawndo “It’s got Electrolytes."
Motivation doesn’t trump skills and experience.
I would.
Not really. There certainly were more people that did, but not everone.
I doubt that very much. They may not be as knowledgeable as a farmer from those days, but they aren’t as stupid or ignorant as you make out.
But, just in case, let’s bring some books on farming into our shelter as well.
The laser doesn’t move, and doesn’t have any reaction. It sends energy by electro-magnetic transmission, which, if not massless, is nearly so, and one side of the meteor heats up so much that it boils and ejects mass.
If it’s earth-based, it’s going to damage the atmosphere on the way through, and if it’s space based, it’s going to require a nuclear reactor big enough to power America, so there are problems.
I see, OK.
Oh, sure, most modern folks don’t have what it takes to survive an event like this. That’s why we’re assuming that 90% of the population will die. But there are still plenty of people who do have what it takes to ensure that they will survive, as well as a number of their loved ones who wouldn’t survive on their own.
Its transmission would be massless, but that doesn’t mean that it doesn’t have momentum. If you have a laser powerful enough to do anything meaningful to a mountain sized asteroid, it is going to have a noticeable reaction in the opposite direction.
Whether that is an unmanageable amount of thrust depends on a variety of factors, but it would have to be taken into account.
The amount of momentum is tiny compared to the energy transmitted. The former has equal opposite, latter not.
But 1M watts is not much, assuming you can keep it focused in a beam as small as a few hundred meters across by the time it reaches the target. maybe you can actually start making a pit and the vaporising rock or ice can have a reaction effect jetting off one side… but the rock will be spinning, making it more difficult to create a hot spot.
Another quibble - like crocodiles and turtles surviving because the hatchlings are nowhere near the size of the adults that may have trouble finding enough food - similarly, redwoods did not have to survive - just their seeds, had to make it through a few years of winter and then sprout. Small animals with sufficient ability to survive cold weather, let’s say proto-rats, may conveniently find a ready supply of freshly cooked and frozen foodstuffs lying around to keep them going. Even cold-blooded animals may find refuge near freshly created volcanic hot spots and thermal springs. I assume an impact like we’re talking would have shaken loose every tectonic hot spot. More minor biologicals like plankton probably could survive until defrosted.
Tru dat. If you scatter a bunch of anything randomly, you’re going to have places where they’re relatively clumped. That’s the mathematics of arrival processes in a nutshell.
The world’s strongest laser is not going to be strong enough to deflect an asteroid. We are going to need something significantly more powerful.
And my concern is not that the laser is going to be blasted back through space uncontrollably, but that in space, there is nothing to brace against, so even that small force adds up over time. The best ion engines only do about an order of magnitude better than the thrust of this 1 Megawatt laser, and we use those to send stuff out to the asteroid belt.
Even if small, that amount of thrust will need to be taken into account. You are going to be trying to hit something tens of millions of miles away, and any slight inaccuracy means your shot goes wide.
And by its nature, you are also scattering the devastation and the relatively undamaged areas randomly.
You are not going to have some lucky survivors at ground zero, but there could be hundreds of square miles 90 degrees away that is pretty much untouched.
The specific question being addressed, and I think it was an interesting one, is how much recoil an extremely powerful laser would have:
With the to and fro being
and
This being GQ I tried to provide a GQ answer.
The recoil from a laser from even hypothetically absurdly powerful lasers (which would have how much mass?) wouldn’t produce recoil enough to maybe move a can of beer. Unclear if that would be “noticeable” given the mass of such a device. In any case any movement caused that teeny tiny momentum is nothing compared to the fact the movement of the asteroid! Yes any such hypothetical device would need to constantly tracking its target moving relative to it.
As an aside the current record holder for laser power is 10 PW … it is not requiring a separate nuclear reactor. Because each burst is very short (about 25 fentoseconds), but each very short burst is enough to vaporize matter.
As I did. I responded to the claim that it doesn’t move and doesn’t have any reaction. It will move, it will have a reaction. This is fact, not opinion.
It would have to be an additional thing to figure in to track it, otherwise, it will miss. The small difference adds up. If you are only firing it for hours or days, then you just need to make sure it doesn’t throw off your aim. If you are firing it for months or years, then you are going to need to correct your orbit from time to time.