PDA

View Full Version : Science What happens when you have infinite energy?



Accelerator
2020-05-13, 07:38 AM
There was a discussion going on here:

https://forum.rpg.net/index.php?threads/wild-talents-godlike-it-begins-now.315838/page-10

\
Hell, a Wild Talents engineer could build a generator the size of a d-cell that tunnels back to the Big Bang with a proton sized wormhole to generate a practically limitless- if narrow- stream of energy. With some extra time and effort, he can make plans ordinary folks can use to build them. Bam. The world economy is on the skids. Put on in your cellphone or laptop, and never buy another battery. Put a bank of them in your car, and never buy gas again. Put a bigger bank of them in your house, and you're off the grid. After the chaos, a new golden age of energy abundance... followed by the troubling realization that all the additional, waste heat generated by the "free energy" and the devices that run on it is slowly cooking the biosphere.
Let's start with the presumption, that 'free energy' is the requirement. There are few spin-off technologies because of this, because if there was, we would be here all day. The basic premise is:We have infinite energy. No need for solar cells, oil, double-A batteries, wind power, or hydroelectricity. Just get a bunch of these guys, and then you have an infinite supply. Not an infinite rate, but that small trickle you get isn't going to run out.

Altair_the_Vexed
2020-05-13, 09:13 AM
"Infinite energy" strongly implied to me that it was all at once.
So my first thought was that "Infinite energy" would cause a new universe or big bang or something equally devastating / creative / unimaginable to happen - but then I read your post, and realised you meant an unlimited supply of energy, not an instantaneous infinite surge.

Then I thought: Is the Big Bang actually an infinite source of energy? No, because the universe isn't actually infinite (in any meaningful way). If there was actually infinite energy in the Big Bang, then there wouldn't be the universe we're sitting in right now.

Then, I thought: If you're tapping this energy out of the Big Bang, then you're changing the initial conditions of the universe.
Depending on your time travel model, you either cause the universe that you're in to be altered, quite possibly ending all life (if you're lucky), or making it so that matter never formed (if you're not so lucky) - and at least making a big time paradox. Seriously, the amount of chaos we've got to deal with over the whole universe's ~14 billion years is such that butterflies causing hurricanes will looks like a perfectly predictable event. Even if you're only taking a tiny fraction, it's still going to change something.

Interesting, maybe - but not very helpful.

So instead, I wondered about the actual question. "Free energy for all" doesn't change so much as you might think. There are still so many resources that we need to make the world work, to let us live. We can't magic those out of the energy we're getting, not without some additional enormous leaps in technology. Matter replicators don't automatically follow on from free energy, sadly.
So we'll still be stuck with haves and have-nots - but we'll be breaking away from the current suppliers / monopolisers of energy sources. Petrochemicals will still be important for our chemical industries and materials, so it's not like there will be no need to keep the oil flowing - but the demand will be massively reduced.
We sort of have a source of near-as-we-need-it-to-be unlimited energy, already: solar. The Sun isn't going anywhere fast (unless you count 230 km/s orbital speed around Galactic Central Point as "fast") - so we can tap that energy at will. But our problem isn't that the Sun is limited, it's that we need storage for that energy - so your D-cell sized Big Bang gate solves that, in much the same way that some sort of perfect battery storage would solve solar.

So once we have abundant, free, unlimited power, we need to put it to work. We need equipment that will run off it. We need to make it safe to use - lithium cells for example are brilliant at electrical energy storage, but they have a nasty habit of exploding if they're not properly regulated. What set of safeguards are we going to put on these Big Bang gates?
I'm an engineer working in electrical product safety - right now, it's taking me all week to prove that a well-established design of a mature technological type is safe for the public, and the test standard that I'm using took a team of maybe a hundred people (including their support staff) over a decade to write, even though they were basing it on existing safety standards - so imagine what we'd need to do to prove that the risk from these wormholes to the origins of the universe are safe.

Again, interesting maybe, but not helpful.
So let's say we fast track IEC 6 000 000: 2020, Big Bang Energy Gateways (Safety) Standard. We have all the electricity we want. Electric cars no longer need an infrastructure of recharging stations. Metals used to transmit power overland are recycled - all those power stations and pylons disappear from the landscape. Hydro-dams can be drained down to leisure lakes and the land re-wilded. Nuclear sites are no longer necessary - so there's no excuse for reactors except to make war: far easier to control.
So much of the cost of things comes from the energy charges to make them. Even thing made by hand need energy for the lighting and heating of facilities. Cost of living comes down. Maybe wages stagnate? I'm not an economist.

TL:DR version - it's big old question! If it could be done safe, it'd be exciting, but not much more than the speculated benefits of Solar Freaking Roadways. I think there'll be less change than you might think. I think there'll be changes we can't imagine.

factotum
2020-05-13, 09:17 AM
I think the quickest answer to this question is "everybody dead". There is no energy conversion that is 100% efficient, so if you are inputting a near-unlimited amount of energy to run things, the losses and inefficiencies in that process will dump extra heat into the atmosphere and gradually raise the planet's temperature to the point where humans can't survive anymore.

Radar
2020-05-13, 09:32 AM
So instead, I wondered about the actual question. "Free energy for all" doesn't change so much as you might think. There are still so many resources that we need to make the world work, to let us live. We can't magic those out of the energy we're getting, not without some additional enormous leaps in technology. Matter replicators don't automatically follow on from free energy, sadly.
Star Trek like replicators might not happen just like that, but actually free energy opens up a lot of possibilities for recycling and overally material extraction technologies that we could already use right now, but they are simply too costly.

Aside from an energy source, those little gates could be used as precise atomic scale cutters and maybe even propulsion. This last possibility would be a game-changer for space exploration, since it would make fuel tanks and reaction mass obsolete. Trips to the orbit would become cheap and any spacecraft going anywhere in the Solar system (or further away) could use full throttle all the time, which right now is way out of question.

Rydiro
2020-05-13, 10:29 AM
Then I thought: Is the Big Bang actually an infinite source of energy? No, because the universe isn't actually infinite (in any meaningful way). If there was actually infinite energy in the Big Bang, then there wouldn't be the universe we're sitting in right now.Side question: What evidence is there that the universe isn't infinite? Most arguments seem to be that the observable/reachable universe is finite. Those are outdated as soon as time-travel is involved. I was under the impression that the hypothesis is that the universe always was infinitely large, even at the big bang. Things were just closer together back then.

factotum
2020-05-13, 10:38 AM
Side question: What evidence is there that the universe isn't infinite? Most arguments seem to be that the observable/reachable universe is finite. Those are outdated as soon as time-travel is involved. I was under the impression that the hypothesis is that the universe always was infinitely large, even at the big bang. Things were just closer together back then.

Well, if the universe is infinite but all the matter is confined to a space within 15 million light-years or whatever, is that really a meaningful distinction? There's nothing beyond the "edge" of matter that's important, it's nothing but dark out there. However, the universe isn't infinite now, and it wasn't infinite at the time of the Big Bang, it was just smaller back then. The usual analogy I hear is the three-dimensional version of what happens when you inflate a balloon with galaxies printed on the surface--the galaxies on the balloon surface will grow further apart, but are still confined within the space defined by that surface.

Tvtyrant
2020-05-13, 11:17 AM
Free energy can't really exist. You will melt the planet in the long run (not that long if it is truly unlimited), in the short run nothing stops someone from siphoning of all the energy for resale or to use as weapons. Free or unlimited energy really means a cashless rationed form of energy, like if everyone got an electricity allotment.

Khedrac
2020-05-13, 12:16 PM
Basically this is the key to the plot of "The Gods Themselves" by Isaac Asimov. Not one of his best knwon novels, but a very good book

Tvtyrant
2020-05-13, 12:26 PM
Side question: What evidence is there that the universe isn't infinite? Most arguments seem to be that the observable/reachable universe is finite. Those are outdated as soon as time-travel is involved. I was under the impression that the hypothesis is that the universe always was infinitely large, even at the big bang. Things were just closer together back then.

Space and time are a result of gravity. If there is no mass there is now space, vacuum is literally created by the expansion of mass in the universe. We can't actually know anything about a gravity free environment because all of our ways to interact with it have some amount of gravity. Like there is no before the big bang, there is no outside the universe.

Radar
2020-05-13, 01:06 PM
Well, if the universe is infinite but all the matter is confined to a space within 15 million light-years or whatever, is that really a meaningful distinction? There's nothing beyond the "edge" of matter that's important, it's nothing but dark out there. However, the universe isn't infinite now, and it wasn't infinite at the time of the Big Bang, it was just smaller back then. The usual analogy I hear is the three-dimensional version of what happens when you inflate a balloon with galaxies printed on the surface--the galaxies on the balloon surface will grow further apart, but are still confined within the space defined by that surface.
Observable universe means places we are able to gets signals from. There is no reason to assume there is no matter outside of this area and the actual size of the universe may be infinite. One of the key (and rather reasonable) assumptions in cosmology is that we are not placed in some special spot in the universe.

Whether the universe is finite or infinite depends on the average curvature of spacetime, which in turn depends on the balance between matter and dark energy (whatever it is).

factotum
2020-05-13, 01:17 PM
Observable universe means places we are able to gets signals from. There is no reason to assume there is no matter outside of this area and the actual size of the universe may be infinite.

I'm pretty sure that the concept of an infinite universe is opposed to the idea that everything was formed from a Big Bang, though?

Altair_the_Vexed
2020-05-13, 02:34 PM
Basically this is the key to the plot of "The Gods Themselves" by Isaac Asimov. Not one of his best knwon novels, but a very good book

I was wondering whether it was worth bringing that up, but thought "Nah - too obscure." Trust the Playground to set me right!

Khedrac
2020-05-13, 03:10 PM
I was wondering whether it was worth bringing that up, but thought "Nah - too obscure." Trust the Playground to set me right!
I cannot help but wonder if the originator of the discussion had read the novel and is harking back to it, either consiously or subconsiously. It is such a perfect fit for the concept being dicussed (apart from dating to well before current understandings of the Big Bang) that I think there has to be a link.

Lord Torath
2020-05-13, 03:37 PM
I'm pretty sure that the concept of an infinite universe is opposed to the idea that everything was formed from a Big Bang, though?Not really, no. We can still have a Big Bang and an infinite universe, or at the very least, a universe that is bigger than the visible universe. There's also no limit to how much bigger the non-visible part of the universe can be than the visible part.

And when I say non-visible, I mean it's so far away from us that light from it has not reached us yet (and possibly never will).

factotum
2020-05-14, 03:47 AM
Yeah, but bigger than the visible universe is still finite.

Radar
2020-05-14, 04:20 AM
I'm pretty sure that the concept of an infinite universe is opposed to the idea that everything was formed from a Big Bang, though?
Not at all. It simply means that if the universe is truly infinite, then it always was so. Big Bang theory works in such a case just as well - only with somewhat different initial condition (instead of a point you have infinite space filled with infinitely dense energy), but for our observable part of the universe nothing essential changes (except for the mean curvature of spacetime).

Since the meassured curvature is still very close to 0, whether the whole universe is finite or infinte is still an open question.

Kaptin Keen
2020-05-14, 05:11 AM
I feel considering the size of the universe is a mistake. The universe ... isn't, basically.

The universe is graph paper. Metaphorically speaking. It isn't anything until you draw something on it, and when you do, you'll never talk about the paper - but about what's on it.

In that sense, the universe doesn't have any scale. It isn't.

Consider instead the big bang. It makes sense for us to think of it as expanding from an inifinitely small point, but that too is a misnomer. The universe (the real one, the one that's drawn on the graph paper) has changed shape, it has gone from high energy and low extension to low energy and high extension - but from the perspective of the graph paper ..... it's still an infinitely small point.

But then, I studied philosophy, so it's really the kind of thing I would say. Sure it's mumbo-jumbo. It is not, however, wrong.

Radar
2020-05-14, 05:25 AM
I feel considering the size of the universe is a mistake. The universe ... isn't, basically.

The universe is graph paper. Metaphorically speaking. It isn't anything until you draw something on it, and when you do, you'll never talk about the paper - but about what's on it.

In that sense, the universe doesn't have any scale. It isn't.

Consider instead the big bang. It makes sense for us to think of it as expanding from an inifinitely small point, but that too is a misnomer. The universe (the real one, the one that's drawn on the graph paper) has changed shape, it has gone from high energy and low extension to low energy and high extension - but from the perspective of the graph paper ..... it's still an infinitely small point.

But then, I studied philosophy, so it's really the kind of thing I would say. Sure it's mumbo-jumbo. It is not, however, wrong.
Whether we consider spacetime itself as a real object or not, the matter filling it out is something and not nothing. Therefore consideration of the size of the universe makes just as much sense, if we are talking about the distribution of matter as if we were talking about the size of the spacetime itself. Yes, the inititial condition of infintie density and infinitesimal size is not exactly correct, but I do not think that any one of us has studied cosmology enough that it makes any significant difference for the discussion.

Additionally, considering spacetime as a real object has many conceptual advantages, since it has its own dynamics and can store as well as transmit energy.

Knaight
2020-05-14, 05:41 AM
The waste heat issue is pretty marginal. This is essentially a black body heat flow problem, where the net heat into and out of earth is zero (otherwise a temperature change would happen). The genericized energy (and material) balance equation here is Accumulation = Input - Output + Generation - Consumption, or A=I-O+G-C. Sign convention can vary a fair bit. The really key bit is that most of these are black box constants we can basically ignore, so we have 0 = I - aT4 + G, where a is a constant that's a giant mess of greenhouse gases, albedo, fundamental constants, etc. Some quick algebra gives us T4 = ((I-G)/a). Our actual heat problems, specifically global warming* are a problem because we're changing a, which can have a really big effect. Looking at I-G though, I is the total input of power from the sun, G is mostly radioactive decay and the like, but also includes the actual heat produced by chemical changes done for power. I is an absolutely ridiculous amount of power, and the subset of G made by people is negligible. Attaching infinite energy sources to very finite power supplies doesn't change this.

On a universal level, sure, more energy is being introduced to the system, radiated away from the earth, and it does technically have to end up somewhere. A negligible rounding error on the planetary scale becomes far, far less than that on the universal scale.

*I use the term instead of climate change here because I'm specifically looking at average temperature and not the various knock on changes.

factotum
2020-05-14, 07:37 AM
I is an absolutely ridiculous amount of power, and the subset of G made by people is negligible. Attaching infinite energy sources to very finite power supplies doesn't change this.


You're assuming that our energy usage wouldn't change if we had effectively unlimited supplies of it, but I doubt that would be the case.

Kaptin Keen
2020-05-14, 07:40 AM
Whether we consider spacetime itself as a real object or not, the matter filling it out is something and not nothing. Therefore consideration of the size of the universe makes just as much sense, if we are talking about the distribution of matter as if we were talking about the size of the spacetime itself. Yes, the inititial condition of infintie density and infinitesimal size is not exactly correct, but I do not think that any one of us has studied cosmology enough that it makes any significant difference for the discussion.

Additionally, considering spacetime as a real object has many conceptual advantages, since it has its own dynamics and can store as well as transmit energy.

But ... that's what I said :p

Strigon
2020-05-14, 09:06 AM
One big question is how power-dense and durable are these devices supposed to be? Because, as mentioned, we have practically infinite energy in solar panels already, but they're very heavy and fragile for the power they offer.
If they don't supply enough power, we might still be using fossil fuels for transportation and the like. If they're sufficiently power-dense, though, every industry will be revolutionized. Energy input is a huge bottleneck that people don't even realize under normal circumstances.

And, as for the whole "heating up" thing... that's just not the case. Of course energy produces waste heat; that won't ever go away. But right now, most of our energy comes directly from combustion - that produces a lot of heat. Nonetheless, it isn't appreciably warming the biosphere. That's the greenhouse gases, which will be reduced by our adoption of this magical technology. Even a massive increase in power production likely won't heat things noticeably; think how much thermal energy there is in the planet's core. Way, way more than we could need in the foreseeable future, unlimited energy or not. And it's just sitting below our feet, sometimes spewing violently into the surface. In the absolute worst-case, infinite energy production makes energy transfer a simple proposition; heat is pumped into a block of, say, tungsten carbide, cooling the outside. This wouldn't be 100% efficient, so there would be a net increase of heat for the system as a whole, but that doesn't matter as long as the outside still gets cooler. Then we send it up to space, likely on a space elevator, where radiators and a reflector dish essentially beam the heat away from Earth.

The whole process requires a lot of energy, but who cares? As long as the net temperature from the whole procedure planet-side is negative (which could be achieved), you've solved the issue.
An issue which, I remind you, likely wouldn't exist anyway.

Radar
2020-05-14, 12:12 PM
But ... that's what I said :p
Considering that you started with:

I feel considering the size of the universe is a mistake. The universe ... isn't, basically.
and I at least tried to argue that size of the universe does make sense as a concept (just as size of Earth's surface as meassured on said Earth) we might have misunderstood each other, or I am now not sensing some irony. :smallsmile:

gomipile
2020-05-14, 12:49 PM
You're assuming that our energy usage wouldn't change if we had effectively unlimited supplies of it, but I doubt that would be the case.

We'd be able to use a lot more free energy than we use now and still maintain a heat balance similar to pre-industrial Earth in the long term. And we'd be able to use it to power carbon capture in the short term, letting us ramp up safe power usage very quickly if we had to.

In the long term, we could build dedicated radiator megastructures if we had to, to send waste heat directly into space, skipping the atmosphere. We'd be replacing our current power grid with a heat pump grid, essentially, but it would be a massive upgrade in our energy production per square area of land devoted to power infrastructure.

Knaight
2020-05-14, 09:16 PM
You're assuming that our energy usage wouldn't change if we had effectively unlimited supplies of it, but I doubt that would be the case.
There's room for it to change and stay pretty negligible - we can add another order of magnitude, no problem. There's also the very real possibility that energy use actually goes down, with localized sources preventing losses due to inefficiencies in energy travel. Power lines bleed, there are heat losses involved in charging and discharging that come up with storage, etc.

Using 2017 data, the total human energy use was 4.73*10^21 J. Average solar radiation over a year is 2.19*10^25 J.

Normalized, if the amount of light energy we got in a year was 1 the amount of light + human industry would be 1.000216. Using some near 1 exponentiation approximations for temperature and normalizing, if the temperature in Kelvin was 1 from sun it would be 1.00005. Using the 288 K global temperature figure this corresponds to an increase of 0.016 C.

That's an overestimate too, as I completely neglected heat generated by non-human sources on earth, which are significant. Still, we'd need to increase energy use 100 fold to correspond to a 1.6 C increase, which is less than even the most optimistic figures for global warming.

The planet is big, T^4 is a hell of a factor, and messing around with constants is an effective thing.

Kaptin Keen
2020-05-15, 01:24 AM
Considering that you started with:

and I at least tried to argue that size of the universe does make sense as a concept (just as size of Earth's surface as meassured on said Earth) we might have misunderstood each other, or I am now not sensing some irony. :smallsmile:

Well .. you mostly say what I'm trying to say. You then add 'it makes sense to talk about the size of space/time itself' - which is what I'm trying to argue is meaningless.

There is a language inherent to these things that isn't known to me. Like I said, I studied philosophy. But the stuff filling the universe is the drawing on the graph paper - space/time is the paper itself. And of course the analogy sort of ends there, because a piece of paper is quite finite, while space/time isn't.

So I don't think we disagree. Or not much?

Mastikator
2020-05-15, 05:58 AM
There's room for it to change and stay pretty negligible - we can add another order of magnitude, no problem. There's also the very real possibility that energy use actually goes down, with localized sources preventing losses due to inefficiencies in energy travel. Power lines bleed, there are heat losses involved in charging and discharging that come up with storage, etc.

Using 2017 data, the total human energy use was 4.73*10^21 J. Average solar radiation over a year is 2.19*10^25 J.

Normalized, if the amount of light energy we got in a year was 1 the amount of light + human industry would be 1.000216. Using some near 1 exponentiation approximations for temperature and normalizing, if the temperature in Kelvin was 1 from sun it would be 1.00005. Using the 288 K global temperature figure this corresponds to an increase of 0.016 C.

That's an overestimate too, as I completely neglected heat generated by non-human sources on earth, which are significant. Still, we'd need to increase energy use 100 fold to correspond to a 1.6 C increase, which is less than even the most optimistic figures for global warming.

The planet is big, T^4 is a hell of a factor, and messing around with constants is an effective thing.
I think you're onto something, it's more likely to limit future heating of the planet rather than the other way around, since we won't need to release any more greenhouse gases and may even be able to capture existing ones. We could use this energy source to cool the earth back down to reasonable amounts. The added heat could radiate into space.

Rockphed
2020-05-15, 08:21 AM
The Earth recieves about 1370 watts per square meter from the sun. While it has been warming by a fraction of a degree per decade for the last 150 or so years, it has been essentially flat, so I will ignore the specific heat of the Earth. To the sun, the earth is a circle with radius 6371000 and area 1.275 x 10^14. The earth therefore receives about 1.75 x10^17 watts, or about 15 x 10^22 joules per day. Over the course of a year the Earth also reflects, dissapates, and otherwise disposes of almost the same amount. Humans used about 5.67 x 10^20 joules in 2013, which averages to about 1.55 x 10^18 joules per day. We could increase our energy usage by about 100 times and still be less than solar variance (which I think is about 2%).

Rydiro
2020-05-19, 06:55 AM
Well .. you mostly say what I'm trying to say. You then add 'it makes sense to talk about the size of space/time itself' - which is what I'm trying to argue is meaningless. Well, it would be pretty meaningful, if the universe as a whole can be experimentally measured. If its finite, you could say how big it is. If its infinite, you could still say something about its shape/topology. I think attempts have been made.

gomipile
2020-05-19, 08:10 AM
I feel considering the size of the universe is a mistake. The universe ... isn't, basically.

The universe is graph paper. Metaphorically speaking. It isn't anything until you draw something on it, and when you do, you'll never talk about the paper - but about what's on it.

In that sense, the universe doesn't have any scale. It isn't.


That view is inconsistent with our current best theory and observations on the large scale structure of spacetime, Einstein's general relativity.

Spacetime does have observable, measurable structure even where there is no local matter or energy. That has been directly observed and quantitatively measured in our universe in quite a few different ways.

Leaving the observable universe behind for the sake of argument, and going to the theory, it is even possible to have nontrivial vacuum solutions of general relativity with absolutely no matter or energy in a universe. By nontrivial, I mean that the Riemann curvature is nonzero and possibly also not constant. In the cases where the Riemann curvature is both nonzero and not constant, there is absolutely a structure to that spacetime that changes from place to place. Different places in such a spacetime have different properties, at least up to the degrees of freedom determined by the symmetries of the vacuum solution being considered. Such a spacetime can have features with a measurable scale to them. That is, some of these solutions will look different if you change the length scale you're looking at. Given the constants of the universe, you could take measurements within such a universe to determine the length of an approximately rigid object like a ruler or meter stick, for example.

Rydiro
2020-05-19, 08:51 AM
_Cool stuff_Do gravitational waves have energy? And if so, do they affect spacetime (beyond waving)?

gomipile
2020-05-19, 11:14 AM
Do gravitational waves have energy? And if so, do they affect spacetime (beyond waving)?
They take energy to produce, and impart energy to matter and energy concentrations they pass through.

They affect the temporary shape of spacetime while they pass, yes.

Both of these are what allow us to detect them at all with instruments like the LIGO detectors.

Rydiro
2020-05-20, 07:32 AM
They take energy to produce, and impart energy to matter and energy concentrations they pass through.

They affect the temporary shape of spacetime while they pass, yes.

Both of these are what allow us to detect them at all with instruments like the LIGO detectors.So, could you make a stable black hole out of gravity waves? Just asking for a friend.

Lord Torath
2020-05-20, 08:14 AM
Please clarify what you mean by "Stable Black Hole".

Anymage
2020-05-20, 10:06 AM
So, could you make a stable black hole out of gravity waves? Just asking for a friend.

In theory anything with enough energy could form an event horizon, so yes.

In practice, even an arbitrarily advanced society would have much more effective ways of making a black hole if they wanted one. Even in a sci-fi setting, I can't see why anybody would do this unless you're just looking to spruce up your technobabble and don't care overmuch about the real-world meanings.

Rockphed
2020-05-20, 10:25 AM
So, could you make a stable black hole out of gravity waves? Just asking for a friend.

In theory you could get enough energy density of gravity waves to create a black hole. Getting sufficient density of light is ridiculously hard, and light is probably the easiest of the fundamental force carriers to control. Gravity is significantly harder and we do not currently have any means to direct it, so you would have to figure out how to handle the 1/r^2 losses. With light you can set things up so that the energy density increases with distance away from from your source (thanks to lasers).

warty goblin
2020-05-20, 02:52 PM
Unless I'm really missing something, the energy density of a laser still decreases with distance, because the photons spread apart as a function of the wavelength.

gomipile
2020-05-20, 07:43 PM
Unless I'm really missing something, the energy density of a laser still decreases with distance, because the photons spread apart as a function of the wavelength.

I think what was meant is that with a laser, one can set up a situation where the intensity of a beam increases with distance up to a chosen focal point, after which it starts spreading normally. Yes, the maximum possible intensity at the focal point will be less the further away the focal point is set up to be. That's restricted by the spread you're thinking about, of the beam produced by the laser hardware itself.

However, in practice the intensity of the entire beam will still be increasing up until that point.


What one would do is take a collimated beam, put it through diverging optics, collimate it again at the desired minimum initial intensity for a short distance, then pass it through focusing optics with the desired focal point. The maximum intensity at the focal point will be limited by the laser hardware and the total distance traveled, including within the mentioned optics.

Anymage
2020-05-20, 08:29 PM
Getting sufficient density of light is ridiculously hard, and light is probably the easiest of the fundamental force carriers to control. Gravity is significantly harder and we do not currently have any means to direct it...

Since gravity waves travel through spacetime itself, I'm sure that there's some way to assemble galaxies such that gravity waves from multiple sources all get lensed and focused at a single point. (Which might require some elements of some paths to require exotic matter, at which point our best hope of acquiring that is through magic.)

Which does get back to the question of why a society able to manipulate entire galaxies and to cause other black holes to collide at exactly the right places and exactly the right times would bother to do that, since as you mentioned it'd be much easier to just make a black hole by cramming together a bunch of mass and/or light where you want in the first place.

Rockphed
2020-05-20, 09:30 PM
Unless I'm really missing something, the energy density of a laser still decreases with distance, because the photons spread apart as a function of the wavelength.

Fun fact: lasers are weird. The field intensity of a laser looks the same whether the laser is focusing (getting smaller) or diffusing (getting bigger). How tight the laser can be focused is a function of both frequency and how quickly it is being focused (with farther focal lengths having tighter focusing). If I have a laser that at its output has an energy density of 5 W/m^2 and a 1 m^2 aperture, I can focus it down to a much smaller area, still have almost 5 watts, but an energy density in the hundreds or thousands of watts per square meter. If I align several lasers so their focuses are in the same spot, I can add together their energy densities (because electromagnetism is, to the best of our knowledge, linear in a vacuum). I don't remember the theoretical amount of energy density you need to make a black-hole with UV light, but I do remember that it was something absurd.

Rydiro
2020-05-21, 01:08 AM
Please clarify what you mean by "Stable Black Hole".It still being there a few days after waves stop transfering energy into it.
You know, long enough to destroy a star system with a spacetime Eddy.

factotum
2020-05-21, 01:22 AM
It still being there a few days after waves stop transfering energy into it.
You know, long enough to destroy a star system with a spacetime Eddy.

Black holes, once they exist, don't go away again until they evaporate via Hawking radiation, and that's a very slow process for even a relatively small black hole. Also, just creating a small black hole somewhere in a solar system wouldn't destroy it unless said black hole was of stellar mass--black holes are not the cosmic vacuum cleaners of legend, if you were to somehow convert our Sun into a black hole right now the planets would continue in their orbits as they have for millions of years. Everyone would die because no more sunlight means everything gets very cold very quickly, but they wouldn't get sucked into the black hole.

Lord Torath
2020-05-21, 09:28 AM
It still being there a few days after waves stop transfering energy into it.
You know, long enough to destroy a star system with a spacetime Eddy.To further clarify, do you mean using gravity waves to compact material tightly enough that it forms a black hole? In such a case, the black hole will be as stable as any other black hole of its size.

Or focusing gravity waves so their pull is as strong as a black hole? In which case: see factotum's reply.

Rydiro
2020-05-22, 06:28 AM
To further clarify, do you mean using gravity waves to compact material tightly enough that it forms a black hole? In such a case, the black hole will be as stable as any other black hole of its size.

Or focusing gravity waves so their pull is as strong as a black hole? In which case: see factotum's reply.The latter, i meant a gravitational wave kugelblitz. I wasn't sure if there were relevant differences between light and gravity waves which would result in different properties of the black hole. Anyway, i got factotums answer.

Anymage
2020-05-22, 12:07 PM
I wasn't sure if there were relevant differences between light and gravity waves which would result in different properties of the black hole. Anyway, i got factotums answer.

No-hair theorem. The only relevant traits of a black hole are mass, angular momentum, and charge. (Where sufficiently large amounts of energy in whatever form are treated as their mass equivalent.)

Once the event horizon is up, you can't really tell if the black hole you're looking at is primordial, a stellar remnant, a kugelblitz, or came from God deciding to play Rube Goldberg with gravitational waves.

Rockphed
2020-05-22, 01:52 PM
God deciding to play Rube Goldberg with gravitational waves.

That is perhaps the best description of what we are talking about. I want to sig your post, but I'm not sure the best place to cut off.

Tyndmyr
2020-05-22, 04:00 PM
I think the quickest answer to this question is "everybody dead". There is no energy conversion that is 100% efficient, so if you are inputting a near-unlimited amount of energy to run things, the losses and inefficiencies in that process will dump extra heat into the atmosphere and gradually raise the planet's temperature to the point where humans can't survive anymore.

This should be negligible. It isn't significantly different from burning fossil fuels at a rate far higher than they are being created. However, it's *just* waste heat, and not adding an insulation effect the way greenhouse gasses do. So, it should represent a net improvement over the current status quo.

Yeah, it might be marginally higher than no energy use, but it's certainly less warming than most commonly employed methods by a ludicrous factor.

Furthermore, the earth isn't a closed energy system. Waste heat can and does escape. It's like having a hotter fire instead of building a house with insulation. There'll be some additional warmth, but it isn't going to stick around.

So, at least at anything vaguely close to current population levels, it's not a problem at all.

Now, what happens as a result of problem being sucked out of the big bang way back in time...no idea. Sky's the limit there.

Caledonian
2020-05-24, 05:11 PM
If you're somehow taking energy out of the Big Bang, you're probably responsible for starting that event, as you're disrupting the perfect balance that kept everything in a minimum-entropy singularity. Introducing it again much later in the past might be enough to close the universe again and eventually induce the Big Crunch.

So, mazel tov! You're repsonsible for both the creation, and the destruction, of the entire universe! We hope you're happy.

Khedrac
2020-05-25, 02:13 AM
If you're somehow taking energy out of the Big Bang, you're probably responsible for starting that event, as you're disrupting the perfect balance that kept everything in a minimum-entropy singularity. Introducing it again much later in the past might be enough to close the universe again and eventually induce the Big Crunch.

So, mazel tov! You're repsonsible for both the creation, and the destruction, of the entire universe! We hope you're happy.

I repeat, go and read the Asimov novel "The Gods Themselves", it covers this, despite having been written before current theories of the Big Bang.

Caledonian
2020-06-07, 03:55 PM
The Gods Themselves didn't involve shipping energy around, but something far more esoteric. And until some human scientists devoted themselves to understanding the phenomenon, and then responding to its basic flaw by actively compensating, the "infinite energy source" was going to make our sun, and then all the stars, go nova.