Re: Dark energy-powered devices

[Lawrence Crowell]

On Monday, April 8, 2019 at 4:03:19 PM UTC-5, John Clark wrote:
>
>
> On Mon, Apr 8, 2019 at 3:29 PM Mason Green  > wrote:
>
>
>>
>> *> Here’s another idea I just came up with, that doesn’t harness dark 
>> energy itself so much as the Hawking radiation of the de Sitter horizon.A 
>> civilization could build a sphere around a cold black hole (I.e., a 
>> rotating or charged black hole whose Hawking temperature is lower than that 
>> of the cosmological horizon; such a black hole would need to be very close 
>> to extremal).The sphere would catch the Hawking radiation from the 
>> cosmological horizon, and then feed some of it into the black hole in such 
>> a way as to further decrease its temperature (by pushing it closer to 
>> extremality). The sphere could use the rest of the energy for its own 
>> needs. The black hole and the sphere would keep growing over time.*
>>
>
>
> That could work, for a while. As long as you have a temperature difference 
> you can run a heat engine. The Cosmic Microwave Background Radiation is at 
> 2.7K so if you used a solar mass Black Hole as a heat sink you could 
> extract some work out of it because it has a temperature of only 0006k. 
> But it wouldn't be much as the efficiency would be very low;  and even 
> that pitiful trickle of work wouldn't last forever because over time the 
> Cosmic Microwave Background Radiation will get colder and, as it starts to 
> evaporate and gets smaller and smaller, the Black Hole will get hotter and 
> hotter until it explodes and disappears. 
>
> John K Clark
>

The CMB is not the Gibbon-Hawking radiation from the cosmological horizon. 
The CMB is what happened when the plasma of the semi-early universe 
coalesced into atom and the radiation was released. This happened about 
380k years into the evolution of the cosmos. The Gibbon-Hawking result of 
radiation due to the cosmological horizon.

To start I consider the elementary case is with the accelerated frame. An 
accelerated observer, g = acceleration, is on a hyperbolic path that 
asymptotes to a split horizon. The two horizons occur at some arbitrarily 
chosen origin. A quantum flutuation as a loop at this origin with a radius 
r has null geodesics connecting it to the accelerated frame. Assume this 
 accelerated observer approaches within r = c^2/g of the origin. Then the 
observer has causal contact with the loop throughout this Rindler wedge. 
The loop parameterized by a time or length d = 2πr = 2πct and in Euclidean 
time, since this is an off shell state and an instanton, the unitary 
operator e^{-iHt/ħ} → e^{-2πħωrħ}. Here the Hamiltonian is assumed to give 
energy ħω. Substitute in r = c^2/g we have a Boltzmann term e^{-2πħωc/g}. 
 An identification of this with e^{-E/kT} leads easily to the temperature

T = ħg/2πkc.

So temperature is the same as acceleration! This is a quick an dirty 
derivation of Unruh radiation, which I will admit glosses over some points. 
Some work and the identification of the acceleration with a black hole 
gives Bekenstein-Hawking temperature for a black hole.

The Gibbon-Hawking temperature can be found if we let g = c^2/(horizon 
distance) and for the cosmological constant Λ = 10^{-56}m^{-2}  and R = 
sqrt{3/Λ} ~ 10^{28}m then g ~ 10^{-12}m/s^2 The temperature 

T = ħc^2 sqrt{Λ/3}/2πkc ~ 10^{-30}K.

That is an absurdly cold temperature. In order to use that as an energy 
source you would need to have a cold bath that is even colder. That is not 
really possible. Another way to see it is the wavelength of most of this 
radiation is on the order of the cosmological horizon scale. You would need 
a detector on that scale to detect a boson.

LC

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Re: Dark energy-powered devices

['Brent Meeker' via Everything List]

Why the cosmological horizon?  The CMB is at 2.7degK, which is waaay 
hotter than any black hole you're likely to find.   So you can just put 
a heat engine between the CMB  and the BH.


Brent

On 4/8/2019 12:29 PM, Mason Green wrote:

Here’s another idea I just came up with, that doesn’t harness dark energy 
itself so much as the Hawking radiation of the de Sitter horizon.

A civilization could build a sphere around a cold black hole (I.e., a rotating 
or charged black hole whose Hawking temperature is lower than that of the 
cosmological horizon; such a black hole would need to be very close to 
extremal).

The sphere would catch the Hawking radiation from the cosmological horizon, and 
then feed some of it into the black hole in such a way as to further decrease 
its temperature (by pushing it closer to extremality). The sphere could use the 
rest of the energy for its own needs. The black hole and the sphere would keep 
growing over time.

-Mason



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Re: Dark energy-powered devices

[John Clark]

On Mon, Apr 8, 2019 at 3:29 PM Mason Green  wrote:


>
> *> Here’s another idea I just came up with, that doesn’t harness dark
> energy itself so much as the Hawking radiation of the de Sitter horizon.A
> civilization could build a sphere around a cold black hole (I.e., a
> rotating or charged black hole whose Hawking temperature is lower than that
> of the cosmological horizon; such a black hole would need to be very close
> to extremal).The sphere would catch the Hawking radiation from the
> cosmological horizon, and then feed some of it into the black hole in such
> a way as to further decrease its temperature (by pushing it closer to
> extremality). The sphere could use the rest of the energy for its own
> needs. The black hole and the sphere would keep growing over time.*
>


That could work, for a while. As long as you have a temperature difference
you can run a heat engine. The Cosmic Microwave Background Radiation is at
2.7K so if you used a solar mass Black Hole as a heat sink you could
extract some work out of it because it has a temperature of only 0006k.
But it wouldn't be much as the efficiency would be very low;  and even that
pitiful trickle of work wouldn't last forever because over time the Cosmic
Microwave Background Radiation will get colder and, as it starts to
evaporate and gets smaller and smaller, the Black Hole will get hotter and
hotter until it explodes and disappears.

John K Clark

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Re: Dark energy-powered devices

[Mason Green]

Here’s another idea I just came up with, that doesn’t harness dark energy 
itself so much as the Hawking radiation of the de Sitter horizon.

A civilization could build a sphere around a cold black hole (I.e., a rotating 
or charged black hole whose Hawking temperature is lower than that of the 
cosmological horizon; such a black hole would need to be very close to 
extremal).

The sphere would catch the Hawking radiation from the cosmological horizon, and 
then feed some of it into the black hole in such a way as to further decrease 
its temperature (by pushing it closer to extremality). The sphere could use the 
rest of the energy for its own needs. The black hole and the sphere would keep 
growing over time.

-Mason

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Re: Dark energy-powered devices

[John Clark]

On Sun, Apr 7, 2019 at 7:35 PM Lawrence Crowell <
goldenfieldquaterni...@gmail.com> wrote:

>> There are important differences that need to be explained. You can solve
>> the problem of figuring out if Schrodinger's Cat is alive or dead simply by
>> opening the box and looking, but there is no box you can open to figure out
>> what the 8000th Busy Beaver number is.
>>
>
> > You can't compute outcome prior to an observation.
>

Even if you can't compute Schrodinger's Cat you can still find out stuff
about it but that is not the case with non-computable functions, and that
makes me suspect they have no part to play in physics. Computation can not tell
you what the fate of Schrodinger's Cat was however observation can, but you
can't figure out what the 8000th Busy Beaver number is and probably not
even the 5th. And even if I told you what it was you'd have no way of
varying that what I told you was true.

 John K Clark


>

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Re: Dark energy-powered devices

[Lawrence Crowell]

On Sunday, April 7, 2019 at 5:03:07 PM UTC-5, John Clark wrote:
>
> On Sun, Apr 7, 2019 at 2:26 PM Lawrence Crowell  > wrote:
>  
>
>> > there is no comprehensive axiomatic system for Diophantine equations. 
>> Quantum numbers as Gödel numbers for integer solutions to Diophantine 
>> equations are then not entirely computable and there can't exist a 
>> Turing machine (in the classical sense a q → ∞ convex set) that computes 
>> quantum outcomes.
>>
>
> I think the connection between Quantum Mechanics and  Godel's uncertainty 
> is pretty tenuous. Neither a Quantum Computer or a conventional computer 
> can compute the 7918th Busy Beaver number, and even though its computable 
> and finite its very unlikely a Quantum Computer could compute the Ackermann 
> function in polynomial time which effectively makes it non-computable for 
> practical purposes.   
>  
>
>> > I then maintain the solution to the quantum measurement problem is 
>> that there can't exist such a solution. It is an unsolvable problem.
>>
>
> There are important differences that need to be explained. You can solve 
> the problem of figuring out if Schrodinger's Cat is alive or dead simply by 
> opening the box and looking, but there is no box you can open to figure out 
> what the 8000th Busy Beaver number is.
>
> John K Clark  
>


You can't compute outcome prior to an observation. Quantum interpretations 
are meant to gives some explanation for quantum outcomes, but they all 
contradict each other, but are still consistent with QM. This sound very 
similar to forcing conditions on undecidable propositions.

LC 

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Re: Dark energy-powered devices

[John Clark]

On Sun, Apr 7, 2019 at 2:26 PM Lawrence Crowell <
goldenfieldquaterni...@gmail.com> wrote:


> > there is no comprehensive axiomatic system for Diophantine equations.
> Quantum numbers as Gödel numbers for integer solutions to Diophantine
> equations are then not entirely computable and there can't exist a Turing
> machine (in the classical sense a q → ∞ convex set) that computes quantum
> outcomes.
>

I think the connection between Quantum Mechanics and  Godel's uncertainty
is pretty tenuous. Neither a Quantum Computer or a conventional computer
can compute the 7918th Busy Beaver number, and even though its computable
and finite its very unlikely a Quantum Computer could compute the Ackermann
function in polynomial time which effectively makes it non-computable for
practical purposes.


> > I then maintain the solution to the quantum measurement problem is that
> there can't exist such a solution. It is an unsolvable problem.
>

There are important differences that need to be explained. You can solve
the problem of figuring out if Schrodinger's Cat is alive or dead simply by
opening the box and looking, but there is no box you can open to figure out
what the 8000th Busy Beaver number is.

John K Clark

>
>

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Re: Dark energy-powered devices

[Lawrence Crowell]

An infinite processing does not necessarily require an infinite amount of 
information. A stupid program that just toggles between two states 
endlessly requires a single qubit. A Rabi oscillation of a two state atom 
in a cavity fits the bill, and if it can run forever then in this case as 
there is no input energy needed. Now if you want a program and runs forever 
and that does not come back to the same state except for a finite number of 
times (or if it does return an infinite number of times it is a small 
measure), then you will require an infinite number of states available. 
Entropy of information is S = -k sum_{n=1}^NP_n log(P_n), and an elementary 
case of an infinite number of states, say N → ∞, are states with p_n = 1/N 
and 

S = -k sum_{n=1}^N(1/N) log(1/N) = k sum_{n=1}^N(1/N) log(N) = log(N)

and for N → ∞ this is infinite.

This gets to the heart of a whether nature is discrete or continuous, or 
finite or infinite. We are always faced with a discomfort either way we 
think about this. If things are finite, then we always sense there is 
“more,” and if things are infinite then we run into difficulties 
quantifying that. Infinity is not really a number, but an odd cardinality 
of a set. James Carse wrote a book *Infinite and Finite Games*, which 
compares games of some bounded level of knowability or complexity with 
those unbounded. We have then the notion of finite games as having some 
envelope that defines a “perfect game play,” such as what one can do with 
the game blackjack. Quantum games make even finite games with a known bound 
on a perfect game less knowable, and in some cases unknowable. In fact it 
would take an infinite amount of processing to find the perfect game and 
what the percentage of winning a game is.

Whether space is discrete or continuous is potentially a sort of duality. 
Any causal system must fit in a convex system, such as a bounded region of 
a space, a set or a polytope. Convex systems describe L^p normed spaces 
such that |X|_p = (sum_n x_n^p)^{1/p}. Quantum mechanics is an L^2 system 
such that a sum of probabilities sum_P_n = sum_n|a_n|^2, which is a sort of 
square of a distance in Hilbert space.  The dual of an L^p system according 
to convex sets is an L^q system with 1/p + 1/q = 1 so the dual system is 
also L^2. This is also a metric space system, and it is spacetime. A pure 
stochastic system is a sum of probabilities and is an L^1 system.  The dual 
convex set is a system L^∞, which corresponds to the singular collapse of a 
metric space. This is a completely deterministic system, which can include 
classical mechanics or deterministic Turing machines etc. 

For stochastic systems we have entropy measures. The standard on is the 
Shannon entropy S = -sum_n p_n log(p_n). and there is the relative entropy 
measure S = -sum_n p_n log(p_n/q_n). This is useful for looking at 
conditional entropy, such as S(p|p + dp). It is not hard to see that this 
leads to a metric’

S(P|P+dP) = -½sum_n dp_n^2/p_n

This spans the set of problems with subadditivity. We can generalize this 
with something called the Rényi entropy 

S = 1/(1 – q) ln(sum_n=1^∞p_n^q),

Where this gives the subadditivity rule

S(P + Q) = S(P) + S(Q) + (1 – q)S(P)S(Q).,

where for q = 1 there is no subadditivity. It is also possible to show that 
for q = 1 this gives the Shannon entropy. To do this the limit q → 1 with 
the Rényi entropy and using l’Hospital’s rule. For q = 2 this recovers the 
metric space measure or distance. 

So we can interpolate between these measures. The relationship between 
infinity and finiteness is then evident here. A pure stochastic system is 
difficult to define, but we have a sense that pure randomness is something 
that is not finitely described. In some ways it is not computable, as seen 
with random number generators that give more the appearance of randomness. 
A perfectly random sequence of integers can’t be data compressed beyond 
some measure, and we might be tempted to say they can’t be compressed at 
all. However, even the most random of sequences will contain repeats of 
integers that are compressible. What is this limit? Zurek demonstrated that 
it is not possible to determine if a data compression algorithm is really 
minimal or not. If I compress some data, I can never know whether I have 
the absolutely minimal compression. This is a form of the no-halting 
decision problem, and as this is connected to Cantor diagonalization is 
also ultimately tied to infinity.

However, we have Hawking’s results that the entropy of a black hole is S = 
A/4ℓ_p^2 = N or the number of Planck areas of a black hole horizon. This 
means a discrete structure to spacetime eliminates any infinite content to 
spacetime. So within that setting have some uncertainty on whether it makes 
sense to talk about a continuum of spacetime or whether there really exist 
random numbers in the universe. If the Hilbert spacetime of the universe is 
finite, then in this duality 

Re: Dark energy-powered devices

[John Clark]

In 1972 Bennet  showed that a universal Turing machine could be made both
logically and thermodynamically reversible,[7]
 and
therefore able in principle to perform arbitrarily much computation per
unit of physical energy dissipated, in the limit of zero speed. In 1982 Edward
Fredkin  and Tommaso Toffoli
 proposed the Billiard ball
computer , a
mechanism using classical hard spheres to do reversible computations at
finite speed with zero dissipation, but requiring perfect initial alignment
of the balls' trajectories, and Bennett's review[8]
 compared
these "Brownian" and "ballistic" paradigms for reversible computation.






On Sun, Apr 7, 2019 at 3:21 AM Bruno Marchal  wrote:

> *To sum up: an infinite physical computation does not require an infinite
> amount of energy*


If you want to perform an infinite number of calculations and you don't
have infinite energy available then you'd better have infinite time
available. In 1972 Bennet showed that a reversible Turing Machine could
make a calculation with an arbitrarily small amount of energy but at the
cost of speed; the less energy used the slower the calculation. And if
we're headed for a Big Rip you will not have infinite time.

 John K Clark

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Re: Dark energy-powered devices

[Bruno Marchal]

> On 3 Apr 2019, at 01:36, John Clark  wrote:
> 
> On Tue, Apr 2, 2019 at 5:23 PM Mason Green  > wrote:
> 
> > It appears as though it would indeed be possible to build a device powered 
> > by dark energy. Such a device could keep running forever (as long as the 
> > universe keeps expanding forever and vacuum decay doesn’t occur) and be 
> > able to survive (or prevent) the heat death of the universe. Even proton 
> > decay would not present a problem; new protons could always be created from 
> > the energy generated.
> 
> I agree. 
>  
> > As far as I know, neither of these devices has been proposed before in the 
> > literature; I might have been the first person to come up with them.
> 
> 
> Well... on August 4 2012 I sent this to Fabric Of Reality List: 
>  
> "Could we still extract an infinite amount of energy from the real universe 
> and thus perform an infinite number of calculations? Perhaps.
> 
> Suppose you had 2 spools of string connected together by an axle and you 
> extended the 2 strings to cosmological distances 180 degrees apart from each 
> other. As long as the Dark Energy force between the atoms in the string that 
> were trying to force them apart was not stronger than the attractive 
> electromagnetic force holding the atoms of the string together the string 
> would not expand as the universe expanded, so there would be a tension on the 
> strings, so there would be torque on the spool, so the axle would rotate. The 
> axle could be connected to an electric generator and it seems to me you'd get 
> useful work out of it. Of course you'd have to constantly add more 
> mass-energy in the form of more string to keep it operating, but the amount 
> of mass per unit length of string would remain constant, however because the 
> universe is accelerating the amount of energy per unit length of string you'd 
> get out of it would not remain constant but would increase asymptotically to 
> infinity. If the theories about the Big Rip turn out to be true and the 
> acceleration of the universe is itself accelerating then it should be even 
> easier to extract infinite energy out of the universe; it would just be a 
> simple matter of cosmological engineering. What could go wrong? 
> 
> If you have infinite energy then you can perform an infinite number of 
> calculations, so you could have an infinite number of thoughts, so you would 
> have no last thought (the definition of death), so subjectively you would 
> live forever. Of course the objective universe might have a different opinion 
> on the matter and insist that everything including you had come to an end, 
> but that hardly matters, subjectivity is far more important than objectivity; 
> at least I think so.”  


Doing a physical computation does not require energy, except for the external 
read and write. It is enough to never erase any information. As Landauer found: 
only erasing information requires energy, and as Hao Wang already discovered (I 
think around 1950), but also Church (Lambda-I calculus), there are 
Turing-universal model of computation where no information is ever discarded.

With the combinators, this is illustrated by Turing universal base of 
combinators with no “eliminators”, without kestrel of similar. The kestrel K 
eliminates information (Kxy = x), like a projection, it is not reversible. 

K = [x][y] x (= in Church notation : lambda x lambda y . x). But Church forbade 
using lambda for a variable absent in the core, which is the same as forbid 
elimination of information. Note that quantum computation has to be reversible, 
and never eliminate information (except at some final measurement possible). So 
an infinite physical computation requires only a finite amount of energy. The 
universal dovetailing, which generate and execute all computation, can be 
physically implemented so as using only a finite amount of energy.

But this concerns physical computation. Gödel implicitly and Turing, Post, 
Church and many others will show that the tiny partial computable part of the 
arithmetical reality already implement all computations, including all the 
approximation of all physical computations, and with mechanism, the “real 
physical computation” have to emerge from those computation emulated by the 
arithmetical reality.

This already generates a doubt that physical computation exist, and indeed no 
universal machine can subjectively distinguish a physical computations from a 
purely combinatorical one, or from a purely arithmetical one, or any purely 
mathematical one. But they can detect a difference by doing some measurement, 
given that the physical laws are constrained by Mechanism. That would still be 
undistinguishable from a computation + some special Oracle. No such detection 
have been currently found, and, (finite) machines, although they can suspect 
some oracle (or magic) to be at play, no certainty can be obtained because a 
machine cannot distinguish an 

Re: Dark energy-powered devices

[Lawrence Crowell]

For two galaxies accelerating away from each other one might in an "in 
principle" manner think of a tether connecting these two galaxies. Some 
sufficiently capable ET then manages to build this tether continually out 
of a magnetic material that passes through coils and the Faraday effect 
kicks in. This is not exactly eternal, for eventually these ETs will run 
out of resources in their galaxy, but it does seem to suggest dark energy 
could be mined. 

There is however no "free lunch" per se here. 

https://physics.stackexchange.com/questions/257476/how-did-the-universe-shift-from-dark-matter-dominated-to-dark-energy-dominate/257542#257542

so you can read this without me having to spend the next hour typing this 
up again.

This all stems from the Hamiltonian constraint NH = 0 which then has a 
kinetic and potential part. The eternal accelerated expansion is then just 
a way that ever more negative gravitational potential energy generates ever 
more kinetic energy.

LC

On Tuesday, April 2, 2019 at 3:23:48 PM UTC-6, Mason Green wrote:
>
> It appears as though it would indeed be possible to build a device powered 
> by dark energy. Such a device could keep running forever (as long as the 
> universe keeps expanding forever and vacuum decay doesn’t occur) and be 
> able to survive (or prevent) the heat death of the universe. Even proton 
> decay would not present a problem; new protons could always be created from 
> the energy generated. 
>
> So far I’ve thought of two possible classes of device that could do this. 
> The first is the “giant atom”, consisting of two spheres of equal but 
> opposite charge orbiting each other at an extremely long distance (long 
> enough that dark energy becomes significant). At such a distance, dark 
> energy would cause the objects’ orbits to spiral further and further apart. 
> On the other hand, because the objects are charged, they radiate away 
> energy as they orbit, and this radiation provides a braking force that 
> would cause the objects to spiral closer together. If the two effects are 
> perfectly balanced, the orbits would be stable and the system would keep 
> radiating away energy forever—energy extracted from the acceleration in the 
> universe’s expansion. 
>
> The second device consists of an extremely long spring. Due to dark 
> energy, the spring experiences a fictitious force pulling it apart. This 
> force is stronger when the spring is fully extended, due to the longer 
> distance between the ends. Thus an oscillating spring would experience an 
> oscillating force, and have energy continually added to it, increasing the 
> amplitude of its oscillations. To keep the string from breaking, a 
> mechanism for extracting energy from the spring would have to be added, and 
> if energy is extracted at the same rate it is added the system would be 
> stable. 
>
> As far as I know, neither of these devices has been proposed before in the 
> literature; I might have been the first person to come up with them. 
>
> Perhaps we should look for signs of these devices being constructed, in 
> the event highly advanced alien civilizations might be constructing them. 
> Any civilization that constructs such a device would probably qualify as 
> Type IV. With infinite energy it’d be possible to do an endless variety of 
> things: run a universal dovetailer, or resurrect the dead (simply by 
> resurrecting every person who COULD have ever existed, a set that obviously 
> includes every person who DID actually exist), etc. 
>
> -Mason Green

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Re: Dark energy-powered devices

[John Clark]

On Wed, Apr 3, 2019 at 8:43 AM Mason Green  wrote:

* > It looks like the best hope now might be for a breakthrough or paradigm
> shift in cosmology and/or physics. *


This is certainly no breakthrough but suppose you had a rod and some beads
with holes in them, you thread the beads on the rod and then put some glue
or something on the rod to make it slightly sticky. The chemical bonds in
the rod would keep the atoms in it from getting further apart but the beads
would be free to slide along it, but because the rod was sticky the sliding
would generate heat from friction, and you could run a heat engine with
that and get work out of it. As we got closer to the Big Rip the rod would
get shorter because Dark Energy would start to tare it apart, but that's OK
because even though the rod is shorter the acceleration is greater so the
heat production would (perhaps) be constant.

By the way I got the sticky bead idea from Richard Feynman who used it to
show that Gravitational Waves have energy.

 John K Clark

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Re: Dark energy-powered devices

[John Clark]

On Wed, Apr 3, 2019 at 2:15 AM Mason Green  wrote:


> *> Actually now that I’m thinking about the spring idea some more, it
> seems like you might be right about it not working. Dark energy will change
> the shape of the potential energy/displacement curve for sure, making the
> spring strongly anharmonic. However it doesn’t look like it will result in
> amplitude increase (negative damping) like I thought. However the
> orbiting-spheres system still seems to work,*


If an electrical charge is moving in a circular orbit it is accelerating,
but if that orbit is one that Quantum Mechanics allows it with not radiate
any electromagnetic waves regardless of what Maxwell says. If Dark Energy
enlarges the radius of that quantum allowable orbit I don't know what would
happen, nobody does because nobody has made a link between Quantum
Electrodynamics and General Relativity. However my hunch is it still
wouldn't radiate, after all a electrical charge in a large orbit
accelerates less than one in a small orbit.


> * > As far as cosmological-scale black holes are concerned, I’ve got a
> hunch. I suspect (but cannot prove) that above a certain mass/radius, the
> Hawking temperature of a black hole would start to increase again, due to
> dark energy helping give particles a “push” out of the hole.*


If Dark Energy is constant with time my hunch is it would have little or no
effect on a Black Hole, but if the acceleration is itself accelerating
toward infinity and we're headed for a Big Rip then it's only a matter of
time before Dark Energy would rip everything apart even the most tightly
gravitationally bound objects in the universe, Black Holes. And even
without Dark Energy or the Big Rip Black Holes only have a finite lifetime.

 John K Clark
>
>
>

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Re: Dark energy-powered devices

[Mason Green]

Uh oh, looks like the “giant atom” idea might not work either. I had been under 
the assumption that dark energy would cause two orbiting bodies to spiral 
apart. But on second thought, it seems like what would actually happen is that 
an orbit affected by dark energy would still be stable, it would just have a 
longer period than it would have had in the absence of dark energy. Thus it 
wouldn’t gain gravitational potential energy over time.

It looks like the best hope now might be for a breakthrough or paradigm shift 
in cosmology and/or physics. For instance, if something like Jamie Farnes’ dark 
fluid theory turns out to be true (in which dark energy and dark matter are 
both the same, negative-mass object). Alternatively, it might be possible to 
survive a trip through a rotating black hole into another universe, and when 
that universe’s usable energy is exhausted, just repeat the process ad 
infinitum. (There’s a lot we don’t know about black holes).

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Re: Dark energy-powered devices

[Mason Green]

Actually now that I’m thinking about the spring idea some more, it seems like 
you might be right about it not working. Dark energy will change the shape of 
the potential energy/displacement curve for sure, making the spring strongly 
anharmonic. However it doesn’t look like it will result in amplitude increase 
(negative damping) like I thought.

However the orbiting-spheres system still seems to work, though, and there may 
be other possible devices that function similarly.

As far as cosmological-scale black holes are concerned, I’ve got a hunch. I 
suspect (but cannot prove) that above a certain mass/radius, the Hawking 
temperature of a black hole would start to increase again, due to dark energy 
helping give particles a “push” out of the hole. Not only that, but at least 
some of these particles would be emitted without decreasing the hole’s mass 
(since the dark energy performed the work needed to bring the particle into 
existence). A large enough black hole might radiate away visible light and 
could serve as a “sun” that never goes out. Perhaps by gathering together 
several galaxies’ worth of matter it might be possible to form such a black 
hole? Or perhaps there already is one somewhere in the universe, formed by 
natural causes, in which case all we would have to do is find it.

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Re: Dark energy-powered devices

[Mason Green]

> That would indeed be like a giant atom, so we would have to have a quantum 
> theory of gravity to know if that would work, and we don't have such a 
> theory. Quantum theory tells us those orbiting changes could not be in just 
> any old orbit but can only be in discrete quantized orbits, and the energy 
> radiated away would not be continuous but would come out in chunks . 
> Maxwell's equations are only approximately correct.  

That’s true, but I’m not sure how significant quantum effects (or quantum 
gravity effects) would be on such a large scale.


> I don't think that would work, if it did then if you hung a spring vertically 
> from a hook in a gravitational field and gave it a small oscillation the 
> spring's oscillation would get larger and larger until it tore itself apart.  
> But that's not what we observe.

Well, in a gravitational field like Earth’s the force pulling down on the 
spring is constant (it’s the weight of the spring itself and whatever is 
attached to it, which doesn’t vary significantly with height over the distances 
we observe). With a constant rather than an oscillating force, you won’t get 
amplification of oscillations. Dark energy curves space in a different manner 
than the presence of an ordinary mass like a planet, so the situations aren’t 
exactly analogous.

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Re: Dark energy-powered devices

[John Clark]

On Tue, Apr 2, 2019 at 5:23 PM Mason Green  wrote:

*>So far I’ve thought of two possible classes of device that could do this.
> The first is the “giant atom”, consisting of two spheres of equal but
> opposite charge orbiting each other at an extremely long distance (long
> enough that dark energy becomes significant). At such a distance, dark
> energy would cause the objects’ orbits to spiral further and further apart.
> On the other hand, because the objects are charged, they radiate away
> energy as they orbit, and this radiation provides a braking force that
> would cause the objects to spiral closer together. If the two effects are
> perfectly balanced, the orbits would be stable and the system would keep
> radiating away energy forever—energy extracted from the acceleration in the
> universe’s expansion.*


That would indeed be like a giant atom, so we would have to have a quantum
theory of gravity to know if that would work, and we don't have such a
theory. Quantum theory tells us those orbiting changes could not be in just
any old orbit but can only be in discrete quantized orbits, and the
energy radiated away would not be continuous but would come out in chunks .
Maxwell's equations are only approximately correct.


> *> The second device consists of an extremely long spring. Due to dark
> energy, the spring experiences a fictitious force pulling it apart. This
> force is stronger when the spring is fully extended, due to the longer
> distance between the ends. Thus an oscillating spring would experience an
> oscillating force, and have energy continually added to it, increasing the
> amplitude of its oscillations.*
>

I don't think that would work, if it did then if you hung a spring
vertically from a hook in a gravitational field and gave it a small
oscillation the spring's oscillation would get larger and larger until it
tore itself apart.  But that's not what we observe.

John K Clark





>

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Re: Dark energy-powered devices

[Mason Green]

I saw a discussion on Physics Forums about an idea similar to yours (involving 
spools of string steadily unrolling due to dark energy. One poster asked what 
would happen once the string ran out, the other person said you could just 
create more length of string with the energy you generated.

There is the issue of what happens when the string becomes too long; the force 
from dark energy would make it snap, even if it were made from carbon 
nanotubes. 

I think what makes my ideas different is that they involve oscillatory motion 
(cycles) rather than linear. I hadn’t seen any ideas like that before.

Another dark energy-related problem I’ve been thinking of a lot is how dark 
energy would affect large (cosmological-sized) black holes. Would the black 
hole become more massive over time (like reverse Hawking radiation) due to dark 
energy pulling it apart? Of course the usual equations relating mass to 
Schwarzschild radius and temperature, etc. would no longer hold.

-Mason

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Re: Dark energy-powered devices

[John Clark]

On Tue, Apr 2, 2019 at 5:23 PM Mason Green  wrote:

*> It appears as though it would indeed be possible to build a device
> powered by dark energy. Such a device could keep running forever (as long
> as the universe keeps expanding forever and vacuum decay doesn’t occur) and
> be able to survive (or prevent) the heat death of the universe. Even proton
> decay would not present a problem; new protons could always be created from
> the energy generated.*


I agree.


> * > As far as I know, neither of these devices has been proposed before in
> the literature; I might have been the first person to come up with them.*
>


Well... on August 4 2012 I sent this to Fabric Of Reality List:

"Could we still extract an infinite amount of energy from the real universe
and thus perform an infinite number of calculations? Perhaps.

Suppose you had 2 spools of string connected together by an axle and you
extended the 2 strings to cosmological distances 180 degrees apart from
each other. As long as the Dark Energy force between the atoms in the
string that were trying to force them apart was not stronger than the
attractive electromagnetic force holding the atoms of the string together
the string would not expand as the universe expanded, so there would be a
tension on the strings, so there would be torque on the spool, so the axle
would rotate. The axle could be connected to an electric generator and it
seems to me you'd get useful work out of it. Of course you'd have to
constantly add more mass-energy in the form of more string to keep it
operating, but the amount of mass per unit length of string would remain
constant, however because the universe is accelerating the amount of energy
per unit length of string you'd get out of it would not remain constant but
would increase asymptotically to infinity. If the theories about the Big
Rip turn out to be true and the acceleration of the universe is itself
accelerating then it should be even easier to extract infinite energy out
of the universe; it would just be a simple matter of cosmological
engineering. What could go wrong?

If you have infinite energy then you can perform an infinite number of
calculations, so you could have an infinite number of thoughts, so you
would have no last thought (the definition of death), so subjectively you
would live forever. Of course the objective universe might have a different
opinion on the matter and insist that everything including you had come to
an end, but that hardly matters, subjectivity is far more important than
objectivity; at least I think so."

  John K Clark

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Dark energy-powered devices

[Mason Green]

It appears as though it would indeed be possible to build a device powered by 
dark energy. Such a device could keep running forever (as long as the universe 
keeps expanding forever and vacuum decay doesn’t occur) and be able to survive 
(or prevent) the heat death of the universe. Even proton decay would not 
present a problem; new protons could always be created from the energy 
generated.

So far I’ve thought of two possible classes of device that could do this. The 
first is the “giant atom”, consisting of two spheres of equal but opposite 
charge orbiting each other at an extremely long distance (long enough that dark 
energy becomes significant). At such a distance, dark energy would cause the 
objects’ orbits to spiral further and further apart. On the other hand, because 
the objects are charged, they radiate away energy as they orbit, and this 
radiation provides a braking force that would cause the objects to spiral 
closer together. If the two effects are perfectly balanced, the orbits would be 
stable and the system would keep radiating away energy forever—energy extracted 
from the acceleration in the universe’s expansion.

The second device consists of an extremely long spring. Due to dark energy, the 
spring experiences a fictitious force pulling it apart. This force is stronger 
when the spring is fully extended, due to the longer distance between the ends. 
Thus an oscillating spring would experience an oscillating force, and have 
energy continually added to it, increasing the amplitude of its oscillations. 
To keep the string from breaking, a mechanism for extracting energy from the 
spring would have to be added, and if energy is extracted at the same rate it 
is added the system would be stable.

As far as I know, neither of these devices has been proposed before in the 
literature; I might have been the first person to come up with them.

Perhaps we should look for signs of these devices being constructed, in the 
event highly advanced alien civilizations might be constructing them. Any 
civilization that constructs such a device would probably qualify as Type IV. 
With infinite energy it’d be possible to do an endless variety of things: run a 
universal dovetailer, or resurrect the dead (simply by resurrecting every 
person who COULD have ever existed, a set that obviously includes every person 
who DID actually exist), etc.

-Mason Green

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