SEJDA: Reakce je cokoliv, kde můžeš rozlišit "reaktanty" před a "produkty" po. Nikde není řečeno, že jedněch nebo druhých musí být víc, než jeden.

zajimava uvaha

The sky is silent. No Dyson spheres, no megastructures, no radio signals. After decades of searching across every wavelength, we've found nothing. The usual explanation: maybe we're alone. But what if we're just looking for the wrong thing? Kardashev told us to look for energy — civilizations consuming planets, stars, galaxies. Bigger, louder, brighter. But look at our own history. Every major revolution is a descent toward a smaller scale of matter. And at each step, something counterintuitive happens: the civilization becomes less visible, not more. The pyramids are visible from space. A 2nm chip is invisible to the naked eye. A quantum operation has no macroscopic trace at all. The Yatima Scale measures what Kardashev ignores: how deeply a civilization reads the information content of reality. The core quantity is a ratio — η_Y = I_exploited / I_Bekenstein — the fraction of information a civilization can extract from matter, bounded above by the Bekenstein limit (a hard theorem, not a guideline). It goes from 0 to 1, and 1 is a horizon: any system that saturates its Bekenstein bound is a black hole. Four levels emerge from the structure of matter itself:

Chemical (Y=10): molecular bonds. η_Y ~ 10⁻¹⁷. We read almost nothing of what matter contains. Nuclear (Y=15): the atomic nucleus. η_Y ~ 10⁻¹⁵. A million times deeper, still almost nothing. Fundamental (Y=18): quarks, bosons, the four forces. η_Y ~ 10⁻¹⁴ to 10⁻⁷. Starting to read the source code. (The range reflects genuine uncertainty — a conservative count of quark/gluon degrees of freedom gives the lower bound; a full quark-gluon plasma estimate gives the upper. Resolving this would require lattice QCD calculations.) Entanglement (Y=35): spacetime geometry. η_Y → 1. Reading the whole book. Invisible. Silent.

Three independent formalisms — Bekenstein (information content), Holevo (information extraction), and Szilard-Landauer (extractable work) — converge on the same hierarchy. That convergence is grounded in the Landauer principle, a theorem of statistical mechanics experimentally verified in 2012. It's not a coincidence — it's physics. The Fermi implication is direct. Kardashev predicts advanced civilizations should be MORE visible. Yatima predicts they should be LESS visible. The silence of the sky is consistent with the latter. Any sufficiently advanced technology isn't just indistinguishable from magic — it's indistinguishable from physics itself. This isn't a choice or a strategy — it's thermodynamics. A civilization approaching the Landauer limit extracts more work per bit with less waste heat. Invisibility is a consequence of efficiency, not of hiding. What to look for instead. If Yatima is right, we shouldn't be searching for excess signals — we should be searching for deficits. Infrared deficit zones: a civilization near the Landauer limit produces less waste heat than any natural process, not more. The inverse of a Dyson sphere. Localized entropy anomalies: regions with anomalously low thermodynamic entropy — subtle ordering that natural processes can't explain. Anomalous quantum correlations in the CMB: non-trivial entanglement patterns between distant regions that deviate from perfect thermality. Future instruments (Simons Observatory, CMB-S4) have the sensitivity to look for these. What would break this. A confirmed Dyson sphere would support Kardashev over Yatima. A violation of the Bekenstein bound would destroy the ceiling. And honestly — the prediction that advanced civilizations are invisible has the same logical structure as Sagan's dragon in the garage. What the scale actually claims is not "invisible civilizations exist" but "if technological civilizations exist, physics predicts they become progressively undetectable." That's a claim about the relationship between technology and visibility, not about the universe. Between Level III and IV lies a 17-order-of-magnitude gap of unknown physics — bigger than the entire span from chemistry to particle physics. That's where the map goes blank. This builds on Barrow's miniaturization scale (1998) and Smart's Transcension Hypothesis (2012). What it adds: quantitative formalization, the Bekenstein ceiling, and the convergence argument. Curious what this community thinks — does the hierarchy hold up? Is the observational program viable? Or is this just a more elegant dragon in the garage?

copypaste odsud: https://www.reddit.com/r/IsaacArthur/comments/1r749os/the_fermi_paradox_might_be_a_measurement_error/

SEJDA: Izotop = nuklid. Název článku na kosmonautix je v pořádku.

XCHAOS: jenze s tou stabilitou to taky neni tak jednoduche. Jsou izotopy u kterych predpokladame ze jsou radioaktivni, ale s polocasem rozpadu vyznamne delsim nez stari vesmiru, takze se ta radioaktivita blbe potvrzuje kdyz nejde merit. A izotop muze prakticky existovat jakykoliv, akorat polocas rozpadu je treba tak kratky ze ani nema smysl o izotopu mluvit.

"to mi zatím nikdo uspokojivě nevysvětlil " - no mozna prave proto, ze si musis sam nastudovat aspon ty zaklady. A ne tim ze si prectes hromadu popularni vedy, ale ze proste otevres ucebnici fyziky a pojedes od nuly. Ja osobne si myslim, ze nektere problemy jsou natolik komplexni, ze nejdou vysvetlit youtube videem zkouknutym pri odpoledni pauze. Nekdy proste musis vzit ty rovnice a zacit se v nich hrabat. A kvantovka je presne ten priklad, protoze jakakoliv lidska intuice velmi rychle selze, a clovek se musi spolehnout na rovnice aby neco poznal. A presne tady v kvantovce se nejvic projevuje ta uplne nejhorsi vec, kdyz nekdo zacne stavet vzdusne zamky na zaklade znalosti z popularni vedy. Napriklad ta tvoje zminka s teorii casu a emergentnim kvantovym jevem.

Celkem vtipne povidani o misi Artemis II:
zlate hreby:
Je to mene nez Apollo 8.
Podoba se draze Apolla 13.

Návrat na Měsíc
https://www.youtube.com/watch?v=47FpXrL6NH0

XCHAOS: o pricinach toho, proc ten ktery izotop ma ten ktery polocas, se na wikipedii a podobnych jednoduchych zdrojich mlci, protoze to je kurevsky slozity problem z kvantove mechaniky s desitkami az stovkami castic, a je matematicky natolik obtizny, ze bez mnohaleteho studia problemu nejses schopen se v tom ani zorientovat.

Takze veda je nejchytrejsi na celem svete, protoze ti ostatni jsou natolik blbi, ze misto aby otevreli ucebnici kvantovky, tak radeji pisou radoby chytre aforismy na nyx.

SEJDA: reakce je proste cokoliv, kde muzes napsat sipku, neco nalevo od sipky a neco napravo. Pocet nalevo a pocet napravo nehraje roli pri oznaceni zda to je reakce nebo neni.
Treba rozpad s uvolnenim beta zareni je reakce zapsana takto:
H -> He + e + v_e
cisylka u H a He si laskavy ctenar doplni sam.
Odprost se od nejakych predstav, a nechytej se slovickareni. Reakce <=> sipka v zapisu.

SEJDA: ale neodporuji. jaderny rozpad je taky reakce. jaderna reakce. jen proste nastava reakce mezi casticemi v jadre, a ne mezi dvema atomy.

SEJDA: fuze muze nastavat mezi deuteriem, triciem, heliem, sodikem, beryliem, borem a vlastne cimkoliv dalsim, a klidne mezi radioaktivnima vairantama tehoz. Klidne muzes provest fuzi dvou jader uranu, pokud mas dost energie a nevadi ti ze se to okamzite samovolne rozpadne. DT reakce je jen jedna z mnoha, ale ma vyhodu ze je snadnejsi nez jine a dostanes z ni spoustu energie. proto ji zkouseji v tokamacich.

SEJDA: fúze je taky jaderná ale není štěpná :D