A-L-E-X wrote:Source of the post There is such a thing as below absolute zero temps and that is what this other universe would be like to us
PlutonianEmpire wrote:Wow, that is indeed fantastic writing!
I do have some new questions of my own. I was reading some tin foil hat stuff to laugh at, and I ran across one article claiming that they know about aliens who breathe C02 and supposedly stop aging upon maturity, and that O2 causes aging.
Lets take this apart.
My first question, what would it take for organic lifeforms to evolve and thrive under an atmosphere similar to Earth, with the exception that O2 and C02 have switched places (0.21 atm of CO2, 400 ppm of O2)?
Second question, we know O2 is an oxidant. What's the likelihood that it causes aging? How do we know if it does or if it does not?
Final question, if we were to find that O2 were somehow to blame for aging, how would humans need to evolve to breathe another substance that somehow keeps us young forever? How would we know if we'd be able to adapt to a new element to breathe in the first place?
Bonus question, if we taught ourselves to breathe CO2, wouldn't that open up every lifeterra ever in SE to us? :lol:
Watsisname wrote:(Transferring over from the discussion in the Future of Humanity Thread)A-L-E-X wrote:Source of the post There is such a thing as below absolute zero temps and that is what this other universe would be like to us
Negative temperature is indeed a real thing (experiments have even produced it), and it is very interesting. But it's also very often misunderstood. I've wanted to make a post about it for a while actually, so perhaps now's a good time to do it.
Negative temperature comes from the definition of temperature in statistical mechanics. Normally we think of temperature as "average kinetic energy per particle" in a system, but really it means something much more general, which might not even have anything to do with kinetic energy at all.
Formally, the definition of temperature is "the change in energy of the system with respect to the change in entropy of the system". Positive temperature refers to a system which increases entropy as it gains energy. Most systems behave that way. But there exist systems where the entropy can be increased by giving up energy. Those systems will be "very eager" to give up their energy in any way possible, since any process that increases the entropy is favored. In a sense, negative temperature would actually better be called "hotter than infinity", since those systems will shed their energy to any other system at any temperature.
The way to obtain negative temperature actually isn't that complicated, nor is it very hard to understand how it works. You can understand it by an analogy to coin flips! (I'll use a little bit of math to show this, but will try to keep it as simple and visual as possible).
Suppose you have some assortment of coins, which may be heads or tails. Each specific arrangement of heads and tails is a "microstate" of the system. For example, HTHHTHT. And each unique total number of heads is a "macrostate". For example, having a total of 4 heads and 3 tails.
The entropy of the system is related to how many microstates lead to the same macrostate. The macrostate "4 heads, 3 tails" has 35 microstates, or 35 unique ways to arrange 4 heads and 3 tails. (Feel free to write them all out to check.) If we have 4 heads and 3 tails, and 35 ways to arrange them, then the entropy is the natural log of 35, or about 3.55. (Actually it would be that divided by the Boltzmann constant, but let's ignore that because it is just a scaling factor). Anyway, without getting bogged down in math, let's think about how the entropy of this system of 7 coins depends on the number of heads.
If we have the macrostate "0 heads and 7 tails", then the entropy is zero, because there is only one way to arrange all heads, and the natural log of 1 is zero. Similarly, the macrostate "all heads, no tails" is also zero entropy.
If we have 1 coin be heads then there are 7 ways of arranging it. HTTTTTT, THTTTTT, TTHTTTT, etc. The entropy is ln(7) = 1.95. And we can work through the rest. To save time, I'll just plot the results:
The entropy is highest at 3 heads and 4 tails, or 4 heads and 3 tails (and same for both since it's symmetric). This makes sense -- there are many more ways to get roughly half heads and half tails than to get all heads or no heads.
Now let's think of this in terms of temperature. Positive temperature means entropy increases with energy. If the number of heads was related to energy, then at 0 heads (0 energy), entropy increases very quickly, because gaining one more head (one more unit of energy) shifts the entropy up a whole lot. But temperature is change of energy with entropy, so this means 0 heads is a very low temperature.
As we move toward the middle of the graph (3 heads), the entropy curve flattens out. Going from 3 heads to 4 heads doesn't change the entropy at all. This means the temperature is infinite. Weird, yes. Then the entropy starts decreasing. There are fewer ways to arrange 5 heads and 2 tails than to arrange 4 heads and 3 tails. The temperature in this region is negative. Adding energy decreases the entropy.
Of course, this is just coin flips. There isn't really an energy associated with the number of heads, so there isn't really a temperature for it, either. However, there is a very simple system whose energy, entropy, and temperature does behave in exactly this way! It is known as a 2-state paramagnet. It is made up of tiny magnetic dipoles that can either be oriented "spin up" or "spin down". Like electrons orbiting atoms, which are either spin up or spin down. By analogy to the coins, having all the spins be spin up or all be spin down is a very low entropy state. A very high entropy state is to have half the spins be up and the other half be down. There are many more possible ways of getting that state -- many more microstates for that particular macrostate.
There's one more thing we must know about the 2-state paramagnet. Normally all the spins are basically random. But if we apply a magnetic field, they will "want" to align with that field. If the magnetic field points up, then we will encourage more of the spins to flip into the "spin up" position. Spins oriented with the field have lower energy, while spins oriented against the field have higher energy.
So what experimentalists actually do to achieve negative temperatures in the lab is to place a two-state paramagnet in a magnetic field, and chill it down to very close to absolute zero. This way the system has very little thermal energy, and instead the majority of the energy is in the arrangement of the spins -- whether they are spin up or spin down.) With the spins being roughly half up and half down, it's in a high entropy state. Then they ramp up the magnetic field, which causes the magnetic dipoles to align with it. This like being at 0 heads in our coin analogy. It is a low energy and low entropy state. The temperature is also very low, but still positive.
Now the trick is to quickly flip the magnetic field around. Then all the spins will be opposite the field. They "want" to flip around to align with the field again. And it is still a low entropy state! There is only one way to arrange a system with all spins being the same! So what happens? The system will spontaneously try to flip the spins todecrease its energy and increase its entropy. It has a negative temperature! It will shed its energy to the surrounding environment regardless of the temperature of the environment. Its temperature is "hotter than infinity".
Weird? Yes. Thermodynamics is fun.
This explanation might leave you wondering, "if temperature is change of energy with entropy, and processes that increase entropy are favored, then why do most things tend to cool down spontaneously rather than heat up?" The reason is that although cooling down by losing energy does tend to decrease the entropy, that corresponds to increasing the entropy of the environment, and the increase in entropy of the environment is larger. Leave out a hot cup of coffee, and the coffee will radiate heat, losing both energy and entropy. But the air around it will both gain energy and entropy, and it gains more entropy than the coffee lost.
Stars are weird systems, too. They get hotter as they radiate energy away, as if they have a negative heat capacity.
A-L-E-X wrote:Source of the post What intrigued me about negative absolute temperatures was how we can compare them to speed as some of the same characteristics they have seem to mimic what we think about "FTL" speeds.
A-L-E-X wrote:Source of the post Years ago we used to think thermodynamics precluded the possibility of a cyclic universe, but now we know that it is not only possible, but also possibly favored.
A-L-E-X wrote:Source of the post I was particularly fascinated by the highly intelligent parrot, ALEX (short for Avian Language Experiment) that was tested to be as intelligent as a 5 yr old child, could do basic math, understood the concept of 0 and knew that it's reflection in the mirror was in fact, a reflection! And when his trainer gave him something to eat he didn't want he threw it at her and told her no! Give me what I want lol. And he invented his own words also by combining characteristics of different things that the object he was inventing the word reminded him of.
A-L-E-X wrote:Source of the post Wasn't the amount of oxygen in the atmosphere back then much higher thus the animals were much larger
Watsisname wrote:A-L-E-X wrote:Source of the post What intrigued me about negative absolute temperatures was how we can compare them to speed as some of the same characteristics they have seem to mimic what we think about "FTL" speeds.
Yes, they are comparable somewhat. A good example is that a particle moving faster than c will speed up to lose energy. The speed of light is like an infinite energy asymptote from both directions. Similarly, a system with negative temperature will become more negative as it loses energy.
For the 2-state paramagnet, the temperature asymptotes to +/- infinity as the system approaches an even number of spin ups and spin downs. Here I plot the multiplicity (number of microstates per macrostate, or how many ways the spins can be arranged) for a paramagnet containing 100 spins placed in a magnetic field pointing down, along with its entropy and temperature. 50 spin ups and 50 spin downs is the highest entropy state, with infinite temperature.Aside: Notice in the multiplicity graph that there are about 1029 ways of arranging 50 spin ups and spin downs. That's also how many ways you could flip 100 coins and get 50 heads and 50 tails. Quite a few. And the number of ways you could get say, 10 heads is very small. Now imagine if we made it a mole of coins. This is deeply connected to why the 2nd law of thermodynamics is such a strong statement about why entropy tends to increase.A-L-E-X wrote:Source of the post Years ago we used to think thermodynamics precluded the possibility of a cyclic universe, but now we know that it is not only possible, but also possibly favored.
Well, no, it is not favored. That's not to say it is impossible, and there are theorists out there with various ideas on how it could work, but it is not part of the currently accepted model of cosmology. Data and the Friedmann equations predict endless expansion. The only way to get a cyclic universe out of that is to assert some new fundamental physics to take hold, and there is no observational/experimental support for those ideas.
Back before we understood that the expansion rate was accelerating, cosmologists were very concerned with determining whether the universe had more or less than the critical density of matter, which would lead to either collapse / Big Crunch, or endless (but slowing) expansion, respectively. A popular idea was that if the density was high enough to result in a Big Crunch, then it would be followed by another Big Bang, and likewise the Big Bang that began our universe may as well have also started from a Big Crunch in a previous cycle. And once you go down that line of thinking, of course it leads to the idea of a cyclic universe.
The problem with that idea is that there is no physics for why a Big Crunch should be followed by a Big Bang. It's a singularity state, and we have no physics or maths to handle singularities. For all we know, a Crunched universe remains crunched. So cyclic universe is more of a desire to have the universe work a certain way when there isn't really evidence to support that it works that way.
Stellarator wrote:A-L-E-X wrote:Source of the post I was particularly fascinated by the highly intelligent parrot, ALEX (short for Avian Language Experiment) that was tested to be as intelligent as a 5 yr old child, could do basic math, understood the concept of 0 and knew that it's reflection in the mirror was in fact, a reflection! And when his trainer gave him something to eat he didn't want he threw it at her and told her no! Give me what I want lol. And he invented his own words also by combining characteristics of different things that the object he was inventing the word reminded him of.
Haha! Yeah, Alex does sound like a character! His story is hardly unique though - there are lots of examples of animals like chimps, crows, octopi and dolphins doing human stuff like that. Some of them are just magicians-tricks (Clever Hans), but others are valid examples like Alex. Caution should be exercised when contemplating this sort of thing though, because the question of 'sentience' and intelligence at human levels is a slippery concept and one that we don't have an overarching template for in regards to animals.
I always say that every species is has intelligence suited for their evolutionary niche and no more then necessary. Brains are biologically expensive. Not to say all animals are perfect - but each has their abilities continually fine-tuning to their environment. Some, like our ancestors, found that they could manipulate their environment psychologically via a societal lifestyle and made tools to make up for their other evolutionary physical weaknesses. Over time, this spiraled into a increased dependence on this external manipulation until we are were we are now. Humans aren't 'better' then other animals because of this, nor are other animals like crows and bonobos that use tools similarly, whether or not they are evolving whilst doing this towards a human-type intelligence. Certainly there are benefits to this route, like an understanding of science, and the increased control and understanding of the natural world around you - but this is more of a process then a goal or 'prize' for being 'intelligent'.
With this in mind I wanted to discuss your reference to dinosaurs evolving intelligence a few posts ago - as it is an intriguing topic. Truth be told, we don't actually know if there were or were not intelligent dinosaurs advanced enough to be considered 'sentient' by human standards. I'm not entirely sure, but I don't think any primitive tools or other signs of stone-age technology would preserve well for over 65 million years. Worse would be if the species in question ("Troodont sapiens" ) lived in a region non-conducive to fossilization. Nonetheless, from available fossil evidence, I think we can safely assume that sentient dinos were not present. However, the dinosaurs were not dumb overall. Although the famous Stegosaurus are so dumb that they needed an extra nerve-cluster roughly analogous to an under-developed brain in their hindquarters to control that region, there are many example of 'smart dinosaurs'. For our era however, they were not so smart - most being far less cognitive then modern birds. See what I meant by the above paragraph when I said that an animals intelligence shouldn't be measured against other animals (namely, us) and instead be seen through the context of their environment? Obviously the dinosaurs were smart for their time. However, brain to body ratio sizes suggest that such theropods like Allosaurus fragilis had a ratio size equivalent to Nile crocodiles (which are cunning predators and have a somewhat unexplored loose social dynamic), Tyrannosaurus Rex (and its relatives) had a brain ratio analogous to an emu. And of course you know all about the the Troodontids and Dromaesaurs. Though smart, they were still in the modern sense about half as smart as a housecat or dog. But that is in a modern context and without cinema exaggerations. 65 million years ago they were smartest things around, until:
BTW, have you ever heard of the Kea parrot? They are another modern-dinosaur analog.
A-L-E-X wrote:Source of the post Wasn't the amount of oxygen in the atmosphere back then much higher thus the animals were much larger
Size has very little to do with respiration, and if it did, there wouldn't have been enough Oxygen back in the Mesozoic Era to make any difference anyway. There was more O2 in the air during the Permian Period of the Paleozoic Era, with a peak oxygen content of almost 0.30atm 250 million years ago, just before the Great Permian Extinction Event. This may have even contributed to the extinction, by letting wildfires subsist for far longer then normal. And yet no creatures even approaching the size of dinosaurs existed then. The Jurassic Period had O2 levels of about 26%, and the Cretaceous had about 30% - similar to Permian levels, but dinosaurs had actually began to shrink in overall size during the latter stages of that time - especially the sauropods.
A-L-E-X wrote:Source of the post Wat- some of the evidence that I've read about that favors a cyclic universe is that our universe itself resulted from a previously contracting one. The discovery of huge supermassive black holes very early on in the universe's history has been seen by some scientists as proof that these structures are holdovers from a previous cycle of the universe.
A-L-E-X wrote:Source of the post I was thinking about the idea that once we get to very small scales (and two dimensions) gravity no longer becomes an attractive force, according to relativity.
Watsisname wrote:A-L-E-X wrote:Source of the post Wat- some of the evidence that I've read about that favors a cyclic universe is that our universe itself resulted from a previously contracting one. The discovery of huge supermassive black holes very early on in the universe's history has been seen by some scientists as proof that these structures are holdovers from a previous cycle of the universe.
That's an enormous leap. I don't find it convincing. It is not how we do science. We do not take an unexplained observation, make up an explanation for it, and then say that the original observation is proof of our explanation. Especially when there might be many other possible explanations. To be taken more seriously by other scientists, we must work our explanation into a rigorous model that makes new, testable predictions. Then before we can even speak of it being "proven", those predictions must be verified by new observations, with all other models being falsified.
I would compare it to observing a strange phenomenon in the sky and concluding it is proof of aliens. That has happened many times in the history of astronomy, and so far it has always turned out not to be aliens, but just astrophysics. (Pulsars, quasars, and gamma ray bursts are good examples.) I similarly expect a mundane explanation for the early start of supermassive black holes. It's not like we see that they were around that much earlier than we expected -- the discrepancy with current models is not extreme. And it's not like there wasn't enough material available.A-L-E-X wrote:Source of the post I was thinking about the idea that once we get to very small scales (and two dimensions) gravity no longer becomes an attractive force, according to relativity.
There is no principle of relativity that claims this. Otherwise black hole singularities would not be a prediction of classical general relativity, and there would not be the singularity theorems.
A-L-E-X wrote:Source of the post About dinosaurs, perhaps raptors were the most intelligent. They hunted in packs like dogs
A-L-E-X wrote:Source of the post The Kea Parrot of New Zealand? Is that the one that preys on sheep?! Or is that the Kaka? I always confuse the two lol.
A-L-E-X wrote:Source of the post In a link I posted earlier, it was said that there is no way we can explain those very early supermassive black holes any other way because they could not possibly have formed so quickly after the big bang.
A-L-E-X wrote:Source of the post I remember you posted some mathematical solutions awhile back that do support cyclical cosmology what percent chance would you give for that to be the correct solution?
Stellarator wrote:A-L-E-X wrote:Source of the post About dinosaurs, perhaps raptors were the most intelligent. They hunted in packs like dogs
The Manoraptora group were certainly smart for their time, but not as smart we give them credit to in the modern context. As we have already explored, it is biologically chauvinistic of us and philosophically unfair to say that they were 'dumb'. HOWEVER, let us give credit where credit is due, not any other time. Although these raptors where keen, they did not huntin packs like modern-day lions since they do not have the cognitive abilities to do so. Within the context of their environment, they didn't need to. Instead, most species used a tactic called mobbing (not be confused with an anti-predator tactic of the same name) - one used by similar creatures like Komodo Dragons, Nile Crocodiles and, perhaps more poignantly - the Harris Hawk. Certainly these animals work as a cohesive unit to take down prey - and display a semi-societal capacity to pull off some very sophisticated ploys and tricks to catch their prey - but this behavior rarely extends beyond the hunting and killing of prey, except in family units. In fact, many species of canids (including dogs) don't even hunt in packs, like coyotes and the now-extinct dire wolves.A-L-E-X wrote:Source of the post The Kea Parrot of New Zealand? Is that the one that preys on sheep?! Or is that the Kaka? I always confuse the two lol.
Kea parrots are the ones that eat sheep - as well as other animals. They are quite intelligent and curious creatures. They also have a call that sounds like a child laughing.