FunHub !

… Recently we found evidence that spacetime curvature alone without the need for an event horizon leads to black hole evaporation (… this is pair generation !). …

Great ! Now tell me : what’s the implications of this on cosmological spacetime curvature ?

Original free access article :
https://iopscience.iop.org/article/10.1088/1361-6633/adc82e
Gravity generated by four one-dimensional unitary gauge symmetries and the Standard Model

if i get even 0.01% of what this is, then, they really reached a “Theory of Everything” but it can’t be experimentally tested until quantum gravity things are detected.

i agree with all of this except, you know, when they will have to do maintenance … i guess they will be (they would be) more simply hauling the whole thing out to work at the surface of the sea … in this scenario the mechanical components would be at the top of the sphere and out of the water.

Perfect guess ! (afaik) ρ(concrete) ≈ 2.5 tons/m³
so full sphere ≈ (2.5 x 382) tons = 955 tons
they have 400 t so the cavity removes :
955 - 400 = 555 t … so 7.51m diam. cavity
… so, yes 3/4m thick wall 😌👍 !

indeed i made a very simplified calculation not taking into account increase density of salted water nor increased density because of compressibility of water at 500 m deep. Basically i took 1m³(water) is 1 (metric) ton.

… a sphere nine metres in diameter and weighing 400 tonnes will be submerged off the coast of California at a depth of 500 to 600 metres. It will have a storage capacity of 0.4 megawatt hours (400 kWh) …

i will try a rough calculations : suppose we can have concrete at $100 per ton, then it’s a minimum investment of $40,000. Also suppose electricity is stored with a large added value of 10 cents per kilowatt hour, so, for every cycle a rough gain of $40. By these numbers, 1,000 cycles would pay for the concrete … so, it may look good considering they plan a life of about 50 years for such devices.
On the other hand if competitive battery storage cost only one cents per kilowatt hour (temporary in and out storage) and if concrete and fabrication goes up 10 times to $1,000 per ton then it is not economically viable anymore.

A good calculation of profitability would need to take into account the less than 100% energy efficiency of batteries cycling and of hydraulic energy cycling, … and so many more parameters which have to be studied.

… you’d need some massive …
from the srticle :
… a sphere nine metres in diameter and weighing 400 tonnes will be submerged …

Can you calculate the weight of a sphere of 9 m of displaced water ?
No ? Well, it is 382 tons.
So, the concrete sphere is already massive by itself. “You” don’t need any complicated anchoring.
Same goes with the rest of your mechanical engineering intuitions : you did not work in this domain or study it, did you 😆 ?
Also, stress cycling is bad on most material, yes. But here it is compressive stress and the geometry is symmetric. Without further study, i want to believe this thing has good potential and my intuitions tells me it looks nice. Time will tell 😁 !

(…) quenching supercurrents in a superconducting YBa₂Cu₃O₇ thin disc exposed to an external magnetic field. Supercurrents naturally form to expel magnetic fields from superconductors. "By abruptly disrupting these currents using ultrashort laser pulses, we could generate ultrafast magnetic field steps with rise times of approximately one picosecond (…)

Such a magnetic field (change) will propagate (at the speed of light in vacuum) during that time (10^-12 s) to a distance of about 0.3 millimeter. So, don’t go too far away if you want to see that change happened this fast !

Fixed resistors
https://en.m.wikipedia.org/wiki/Resistor
The TCR of foil resistors is extremely low, and has been further improved over the years. One range of ultra-precision foil resistors offers a TCR of 0.14 ppm/°C, tolerance ±0.005%, long-term stability (1 year) 25 ppm, (3 years) 50 ppm (further improved 5-fold by hermetic sealing), stability under load (2000 hours) 0.03%, thermal EMF 0.1 μV/°C, noise −42 dB, voltage coefficient 0.1 ppm/V, inductance 0.08 μH, capacitance 0.5 pF.

Quantum based resistors :
https://en.m.wikipedia.org/wiki/Quantum_Hall_effect
Quantum Hall effect →
Applications →
Electrical resistance standards :

(…) Later, the 2019 revision of the SI fixed exact values of h and e, resulting in an exact
R_K = h/e² = 25812.80745… Ω.

(this is precise to at least 10 significant digits)

Quantum Ampere Standard
https://www.nist.gov/noac/technology/current-and-voltage/quantum-ampere-standard
.
https://www.nist.gov/noac/technology/current-and-voltage

(…) Quantum-based measurements for voltage and current are moving toward greater miniaturization (…)

(there also been research for defining a quantum based volt standard)

Exploits of a Mom - xkcd
https://xkcd.com/327/

just a taste :

(…) The team found that Claude used components independent of any language to answer a question or solve a problem and then picked a specific language when it replied. Ask it “What is the opposite of small?” in English, French, and Chinese and Claude will first use the language-neutral components related to “smallness” and “opposites” to come up with an answer. (…)

Hi ChatttGPT,
what’s the ethics of commenting a wall of text with your signature only at the very bottom ?

(?) typo :

(…) without robbing me of the chance to lean learn.

i got confused myself … first I thought it was about CAD software … then read many comments … then noticed something was wrong … then looked again carefully at this image of wiki and thought : okay, this is confusing … I can say more … do not know more.

Confusingly, this post is about (animation) movie creation software. Namely : Maya (from Autodesk) v.s. blender

Hi,
Please notice you have to move (or cross post) this to another community (maybe !programming@programming.dev community) … because, once moderators see this post, they will delete it since it is not following the rules of this community !

Edit : whoops, i see you have already cross posted this elsewhere.

Web browser app.
… if it makes a difference from Linux web browsers or whatever other browsers.

(…) if energy is even real.

at my level of comprehension : https://libquotes.com/aristotle/quote/lbd3b5p
To say of what is that it is not, or of what is not that it is, is false, (…)
→ Aristotle

if you want to get serious, read @pcalau12i@lemmy.world in this post.