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The Nature of the Universe, Time Travel and More...

From your link.
"RUDN University astrophysicists have now proven the theoretical possibility of the existence of traversable wormholes in the Friedmann universe. The research is published in the journal Universe."
An interesting choice of words.

I really like proving something is theoretical, especially when it uses theoretical foundations. We'll never know, until someone disproves the theory.

-Will
 
https://www.universetoday.com/165380/the-galactic-habitable-zone/
"The Galactic Habitable Zone
Our planet sits in the Habitable Zone of our Sun, the special place where water can be liquid on the surface of a world. But that’s not the only thing special about us: we also sit in the Galactic Habitable Zone, the region within the Milky Way where the rate of star formation is just right."
"...a steady, long-lived Sun, free of the overwhelming solar flares that could drown the system in deadly radiation, providing over 10 billion years of life-giving warmth. Larger stars burn too bright and too fast..."
"...the other end of the spectrum sit the smaller red dwarf stars, some capable of living for 10 trillion years or more. But that longevity does not come without a cost. With their smaller sizes, their fusion cores are not very far from their surfaces, and any changes or fluctuations in energy result in massive flares that consume half their faces – and irradiate their systems."
"...our neighborhood in the galaxy, on a small branch of a great spiral arm situated about 25,000 light-years from the center, seems tuned for life: a Galactic Habitable Zone."
"Too close to the center and any emerging life must contend with an onslaught of deadly radiation..."
"...at greater galactic radii, we find a deserted wasteland. Yes, stars appear and live their lives in those outskirts, but they are too far and too lonely to effectively spread their elemental ash to create a life-supporting mixture."
-
The Milky Way galaxy is approximately 13.6 billion years old. The Sun is about 4.6 billion years old (roughly 1/3rd the age of its galaxy). Earth is estimated to be 4.5 billion years old, nearly the same age as our Sun. Life is thought to have started 3.7 billion years ago. Homo Sapien first showed up approximately 2 to 300,000 years ago.

From a Galactic estimation, life wasted no time at starting as soon as Earth settled down enough. Really, it seems almost instantaneous. The moment the crust solidified and the ocean formed, life grabbed ahold. That means, in 3.7 billion years of life on Earth, humans evolved after 3.67 billion years. Human-level intelligent life either evolved at an average, ordinary, unremarkable rate, out of the first single cells that floated around 3.7 billion years ago, or we evolved faster than likely or much slower than possible.

What do we suppose the extremes are for the evolution of life? How much time does life need to blossom into a global civilization that is on the edge of real space travel?

Within our special Galactic Habitable Zone, most of the stars that might have a planetary system orbiting them are likely the same approximate age with planets similarly related. Considering how quickly life began on our planet after it settled, life must have begun on nearly all of the ones that have a similar makeup. Perhapse rare, but certainly not few. That Habitable Zone is enormous and populates with millions of stars.

If life can evolve at faster rates, given a similar history of astronomical events, there may be plenty of more advanced intelligent life in our galaxy. However, if we have evolved at an extraordinary rate in the last 3.7 billion years, there may be very few, if any planets with human level life or higher. Ours being the only data point we have at the moment, it wouldn't be all that surprising to discover no other intelligent life has made it the 4 plus light years or more to find us.

Alpha Centauri has a G-type star and 1 observed planet. That's our closest neighbor. The next G-type star is Tau Ceti, 11.9 LY away with 5 observed planets.
7Gdct9VzQFHUYf8Ec8GXmY-970-80.jpg

https://www.space.com/18964-the-nearest-stars-to-earth-infographic.html

How many years away from space travel to Tau Ceti are we? Can such a thing be done without time travel? Is it reasonable to expect 1/2 light speed space travel in the next thousand years or so?

If we are looking at our evolution as an average over 3.7 billion years, and our current expectations of technological evolution is likely to take us to neighboring stars within the next couple thousand years, it really isn't that absurd to think there are others who are a mere few thousand years ahead of us. That's no time at all in the great Galactic scale of the evolution of life. I'm guessing the stars out here, this distance from the center of our galaxy, are within a few thousand years of each other in age. Some older, some younger, but there seems like a very very very high likelihood that life has been blossoming around those other stars for just as long. Intelligent life, on the other hand, it's likely to be very young across the galaxy. We may have to wait until we are able to travel to them.

-Will
 
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Will The Serious said:
https://www.universetoday.com/165380/the-galactic-habitable-zone/
Click to expand...
A factor here that needs underlining is metallicity, which reinforces the narrative. Just after the Big Bang - if that really did happen 13.8 billion years ago - the only nuclei around should have been those of isotopes of hydrogen, helium and lithium created during the first few minutes. I'm waiting to hear if the early abundance of heavier elements that life might require (C, H, O, N, P and S plus traces of elements such as Fe, Zn, Si, Cu, Na, K, Cl, Mg, Mn, Co, Mb... used as cofactors in proteins* or present as ions or in various compounds) has been experimentally measured in detail by JWST and other observations.**

Sufficient tens of millions of years to billions of years must have passed to fertilise newly developing star systems with enough of the heavier elements derived from stellar winds, planetary nebulae, thermal runaway supernovae, core collapse supernovae, and neutron star collisions.

We might be the "First Ones" - we just don't have enough data to know.

* A cofactor is a chemical compound or metallic ion that is crucial to a protein's function, for example in enzymes (a biological catalyst that increases the rate of a chemical reaction - usually by a huge amount), in ribosomes (Mg and Zn), or in haemoglobin to transport oxygen(Fe).

** It seems that oxygen, the third most common element by mass after hydrogen and helium did appear very early on.
This rapid increase in oxygen content occurred earlier than astronomers were expecting. This opens the possibility that with the necessary ingredients, like oxygen, already readily available in the early universe that life may have appeared sooner than previously thought.
Click to expand...
Astronomers use Webb data to measure rapid increase in oxygen in the early universe (phys.org)
[2301.12825] JWST Census for the Mass-Metallicity Star-Formation Relations at z=4-10 with the Self-Consistent Flux Calibration and the Proper Metallicity Calibrators (arxiv.org)

I suspect that nitrogen and carbon would also have been present in the same relative proportions to oxygen as is found today. However, cofactor elements might not have been. An important one is magnesium found in chlorophyll.
CNO cycle - Wikipedia
5DU8s7x.jpg

Populating the periodic table: Nucleosynthesis of the elements | Science
 
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There are a lot of variables that need to come into play for interstellar life (life that can travel between the stars) to arise. If we consider the relative speed at which life first appeared here on Earth after our star and planet were born, we have to conclude that life among similar star systems can't be uncommon.

Of the 53 nearest starts from the list above, there are only 2 other G-type stars, like our own. 2:53 times the number of groups of 53 or so similar stellar neighborhoods in the so called Galactic Habitable Zone is still a lot of stars. If we were to expand our expectations to life supporting stars so they include F-type and/or K-type stars, we add 7 more stars to our sample. That becomes a many as 9 out of every 53 stars that could possibly support planets with life on them. The possibly that this is the only planet in the galaxy with life on it becomes impossibly small.

There is life on other planets.

What our history tells us, however, is that the evolution of life to a level of intelligence similar to our own, may not be very common at all. What we don't know is how difficult it may be for that evolution to occur? It DID happen here on Earth, but it took nearly all of time for it to get this far on Earth. However, I can't imagine, from the relative time tables, that we are not that far from real interstellar travel. A few thousand years more and we may be capable of spreading throughout the Orion arm of our galaxy. That might also mean there could be plenty of evolved life that is a mere few thousand years ahead of us already. Considering the vast number of star systems to explore and the small time frame advanced life may have had to develop, it does not seem certain it has made it from their home to us by now.

Of course, this is all speculation from a very casual thinker, based on logic that is at its most fuzzy. Is it any less legitimate than a proof that is based on theories that are, themselves, just thought experiments? There is math behind the theory of wormholes. Statistics is math and my speculations could easily draw from statistical numbers, but how much further would that really take us in our knowledge?

-Will
 
K class stars account for about 12% of the galactic population of main sequence (MS) stars, G 7.6% and F 3%. 76% are M class. Taking the average mass M* of K, G, and F stars as 0.63 M☉, 0.92 M☉ and 1.22 M☉, their expected life span on the MS is ((M*/M☉)^-2.5)x10^10 years*, so 10^10 years for 1 M☉ (the Sun, G2), 3.2x10^10 years for 0.63 M☉ (K5), 2.6x10^10 years for 0.92 M☉ (G5) and 6.1x10^9 years for 1.22 M☉ (F5). Perhaps the lifespan on the MS might be too short for life to develop very far around many F class stars, but K and G class stars make up around seven times as many MS stars anyway. I wouldn't rule out M class stars altogether. They are so numerous that fortuitous circumstance might allow some of them to host life in their systems - for example, on large moons of gas giants.

One solution to the Fermi Paradox is that once an advanced civilisation has developed computer technology, it's much easier to simulate any number of possible worlds than to go to the inordinate difficulty and inherent risks of trying to visit them. We only imagine we might do it for real perhaps because of a hangover of the colonial expansionism of the past 500 years. I don't think aliens would take kindly to us landing on their planets, claiming them as our own, forcibly converting the inhabitants to Christianity and stealing their gold - even if they didn't die of the diseases we brought with us - or we die of theirs.

* The life span on the MS for M type ( M* < 0.45 M☉) is much longer than this equation would suggest as their cores are subject to convection stirring them up and thus fusion lasts longer than in the non-convective cores of K, G and F type stars.

ETA: Fixed typos in last paragraph caused by old age and wine consumption.
 
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eByuhtlv-Gallagher_BREAKER.png

The Einstein Ring.
That phenomenon of light being bent by the curving of space-time around a gravitational object such as a galaxy.
https://nautil.us/the-enlightening-beauty-of-an-einstein-ring-500597/
The idea is there is a source of light lined up with the viewer and a space-time bending object like a massive star, black hole, or galaxy between the source and the viewer. The rays of light emitted from the source that pass near to the gravity producing object, but not headed in a direction directly at the viewer, are bent around that point of warped space causing the light to change direction, focusing the light towards the viewer instead.

The ring is produced when the alignments are near perfect, otherwise only a partial ring or simply the appearance of the light source being displaced in the sky. What I find interesting is the formation of a ring, rather then a glowing halo. Supposedly, the light source is emitting light in all directions. Those being blocked by the middle object, of course, don't reach the viewer, but what about the light that skirts the gravity source more closely than the light we see in the ring? Why not see all that light too? Why just the ring of light?

I would guess that the light that passes closer to the gravity source is curved even more than the light in the ring, thus it travels away at a trajectory that is not towards the viewer. Only light at a very specific distance from the gravity source is bent at just the right angle to reach the viewer.

I also wonder if that distance for the leasing is the same for all wavelengths of light. That would mean light is affected by gravity exactly the same no matter its frequency. Given light is believed to travel at one speed and one speed only, then we can assume a set mass, or interaction with space-time no matter the wave density.

-Will
 
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According to Einstein's theory of General Relativity, the lensing is the same for all wavelengths of EM radiation in vacuo. If there were dispersion in the visible spectrum, it would show up as a rainbow effect. Gravitational lensing has been measured at radio, visible, and IR wavelengths.

The number of known gravitational lenses is at least 2,400.

Doubling the number of known gravitational lenses (phys.org)

Microlensing has been used to search for planets outside our solar system. A statistical analysis of microlensing observations from 2002 to 2007 found that the majority of stars in the Milky Way galaxy have at least one planet orbiting at a distance of between 0.5 and10 AU.
Most known extrasolar planets (exoplanets) have been discovered using the radial velocity or transit methods. Both are biased towards planets that are relatively close to their parent stars, and studies find that around 17–30% of solar-like stars host a planet. Gravitational microlensing, on the other hand, probes planets that are further away from their stars. Recently, a population of planets that are unbound or very far from their stars was discovered by microlensing. These planets are at least as numerous as the stars in the Milky Way. Here we report a statistical analysis of microlensing data (gathered in 2002–07) that reveals the fraction of bound planets 0.5–10 AU (Sun–Earth distance) from their stars. We find that 17% of stars host Jupiter-mass planets (0.3–10 MJ, where MJ = 318 M⊕ and M⊕ is Earth’s mass). Cool Neptunes (10–30 M⊕) and super-Earths (5–10 M⊕) are even more common: their respective abundances per star are 52% and 62%. We conclude that stars are orbited by planets as a rule, rather than the exception.
Click to expand...
One or more bound planets per Milky Way star from microlensing observations | Nature {paywalled}

The Wikipedia article explains more about the physics.
Gravitational lens - Wikipedia
 
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Interesting ideas about blending statistical thermodynamics with quantum theory in something termed the Measurement Equilibration Hypothesis:
Textbooks tell us that when one performs a quantum measurement of, say, a system in a superposition of two states, then the system will instantaneously, irreversibly, and non-unitarily transform into a system in a single state. This is clearly unsatisfactory as a description of quantum mechanics, as we believe that all other quantum dynamics occurs unitarily via the Schrödinger equation. What’s even more concerning, however, is that this notion of measurement breaks all three laws of thermodynamics: it doesn’t conserve energy, it decreases entropy, and it makes it trivially easy to reach zero temperature.

Reconciling quantum measurement with the laws of thermodynamics will, of course, require a thermodynamic approach to modelling measurements, and this is what we set out to do with this project. We propose a new model for quantum measurements which is fully-quantum, strictly unitary, and consistent with thermodynamics, called the Measurement-Equilibration Hypothesis. In short: we hypothesise that measurement is a form of equilibration in the conventional thermodynamic sense.

In standard pictures of a measurement, the system being measured is treated quantum mechanically, whilst the measuring device is considered to be classical. This is somewhat analogous to the thermodynamic notion of a small system interacting with a much larger one that has been coarse-grained — where we acknowledge we lack complete information about its microstates. In that case, one can think about the smaller system equilibrating with the larger one under some metric, most often temperature (where it is referred to as thermalisation). Equilibration is characterised by an increase in entropy up to some limiting value — it is an entropically favourable process that occurs without driving. So, rather than a model of measurement that decreases entropy, we argue that measurement is driven by an increase in entropy.

The backbone of this approach is the notion of Quantum Darwinism, the idea that quantum systems imprint information on their surroundings in some way, analogously to how decoherence says that surrounding environments impact systems by removing coherences from them. It has been shown that for the idea to work in a way that preserves common-sense ideas about the objectivity of observations, a very specific form of Hamiltonian called a Spectrum Broadcast Structure (SBS) must be involved. We have developed a model for understanding the constraints on when SBS can be achieved by uncontrolled equilibration alone, and found that it is only possible to even approximate such a structure when coarse-graining is involved in the model of the environment. We believe that this is a first stepping-stone to a fully-realised model of measurement as equilibration, and a key to unlocking the century-old mysteries of quantum measurements.
Click to expand...
Measurement & Equilibration — QuIT Physics

The latest edition (3476) of New Scientist has an article describing the MEH and possible experiments that would support it - although not falsify it as far as I can tell. Unfortunately, I can't link the article as it's behind a paywall. This seems to be the latest preprint that describes some of the research:
Textbook quantum physics features two types of dynamics, reversible unitary dynamics and irreversible measurements. The latter stands in conflict with the laws of thermodynamics and has evoked debate on what actually constitutes a measurement. With the help of modern quantum statistical mechanics, we take the first step in formalising the hypothesis that quantum measurements are instead driven by the natural tendency of closed systems to maximize entropy, a notion that we call the Measurement-Equilibration Hypothesis. In this paradigm, we investigate how objective measurement outcomes can emerge within an purely unitary framework, and find that: (i) the interactions used in standard measurement models fail to spontaneously feature emergent objectivity and (ii) while ideal projective measurements are impossible, we can (for a given form of Hamiltonian) approximate them exponentially well as we collect more physical systems together into an ``observer'' system. We thus lay the groundwork for self-contained models of quantum measurement, proposing improvements to our simple scheme.
Click to expand...
Quantum measurements and equilibration: the emergence of objective reality via entropy maximisation (https://arxiv.org/pdf/2302.11253.pdf arxiv.org)

It would be interesting to know how this paradigm fits in with Stephen Wolfram's latest ideas about how entropy and quantum mechanics arise out of Branchial Space, the Ruliad, and irreducible computation.
 
https://writings.stephenwolfram.com/2021/11/the-concept-of-the-ruliad/
This ruliad concept tree, from a physics perspective,
1110swimg1.png

moves inexorably towards higher states of entropy. However, there must be combinations that move backwards, into lower and lower states of entropy. Life, itself is such a combination. A natural occurring combination that results in, not just the perpetual organization of life itself, but in the natural imposing of organization upon the natural world around it.

-Will
 
The Second Law is probabilistic in nature. It has been observed to time reverse for small, isolated (closed) systems of atoms. Life functions by increasing entropy while preserving order and evolving low probability configurations over time. Life itself is not a closed system.
 
Asbo Zaprudder said:
Life functions by increasing entropy while preserving order and evolving low probability configurations over time.
Life itself is not a closed system.
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in a universe of astronomical forces, untrackable events and poorly understood quantum phenomena, the only truly closed system is purely conceptual. Life offers the opportunity for entropy to move into lower states by the evolution of intelligence, giving direction to desire.

Oil is pumped from the ground, refined and put into a tank to feed a combustion engine in a tractor so mountains that have worn down to plains can be built up again. Steady states are unbalanced, dispersed energy is collected and concentrated; one day, stars that have turned to dust and scattered wide may be reconstructed and reignited by the presence and evolution of life. I see every evidence that life does not move towards higher levels of entropy, it can, but not overall.

-Will
 
MEH in short--a watched pot never boils. :)

So, if I want to terraform Venus...could I just stare at some carbon monosulfide or CS tear gas harvested from the atmosphere until an electron or two swaps over and it becomes silicon monoxide for glassy beaches?
 
We are just Boltzmann Brains catalysed by the ratchet of Darwinian evolution. A real Boltzmann Brain would not live long in vacuo without sensory apparatus, abilities to acquire and process nutrients and oxygen and to expel waste products, and an external life-support system. Ego in Guardians of the Galaxy Vol. 2 would be doomed before he could lay his nefarious plans. In all the gin joints in all the possible universes in the multiverse, we happened to get lucky - for a while.
 
Will The Serious said:
in a universe of astronomical forces, untrackable events and poorly understood quantum phenomena, the only truly closed system is purely conceptual. Life offers the opportunity for entropy to move into lower states by the evolution of intelligence, giving direction to desire.

Oil is pumped from the ground, refined and put into a tank to feed a combustion engine in a tractor so mountains that have worn down to plains can be built up again. Steady states are unbalanced, dispersed energy is collected and concentrated; one day, stars that have turned to dust and scattered wide may be reconstructed and reignited by the presence and evolution of life. I see every evidence that life does not move towards higher levels of entropy, it can, but not overall.

-Will
Click to expand...
“What then is that precious something contained in our food which keeps us from death? That is easily answered. Every process, event, happening – call it what you will; in a word, everything that is going on in Nature means an increase of the entropy of the part of the world where it is going on. Thus a living organism continually increases its entropy – or, as you may say, produces positive entropy – and thus tends to approach the dangerous state of maximum entropy, which is death. It can only keep aloof from it, i.e. alive, by continually drawing from its environment negative entropy – which is something very positive as we shall immediately see. What an organism feeds upon is negative entropy. Or, to put it less paradoxically, the essential thing in metabolism is that the organism succeeds in freeing itself from all the entropy it cannot help producing while alive.”
― Erwin Schrödinger, What is Life?

An excellent introduction to entropy, enthalpy and Gibbs free energy:
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Human beings are chemical reactions.
 
Within the body of a laser, atoms give off radiation at just the right wavelength to excite nearby atoms, causing them to release radiation of the same wavelength. The radiation cascades until it becomes a coherent beam — the output of the laser.
Click to expand...
Is that really how lasers work? What happened to refraction and reflection and parabolic mirrors?

-Will
 
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