Ultimate space simulation software

 
A-L-E-X
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

20 Nov 2018 14:24

Thanks I love birds and dinosaurs also.  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.

Animals are far more intelligent and sentient than we give them credit for.  Elephants bury their dead and return to the site year after year, as an example, and they, as well as bonobos/chimps, dolphins, etc., have brains almost as complex as our own.  It's why I support conservation and am against animal testing and factory farming.  We have better ways now (including cloning of body parts for testing.)  And factory farming causes so much misery and pollution that the poor animals try to kill themselves and each other to get out of it.
 
User avatar
Watsisname
Science Officer
Science Officer
Posts: 1752
Joined: 06 Sep 2016
Location: Bellingham, WA

Science and Astronomy Questions

20 Nov 2018 18:39

(Transferring over from the discussion in 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.  Just as your hot coffee sheds its energy to the cooler surrounding air.

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 times 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:

Image



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 to decrease 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.  My coffee is getting cold right now, and the entropy of the universe is increasing because of it.

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
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

20 Nov 2018 23:21

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? :D  :lol:

I found this very intriguing also- and about the aging issue, we are currently working on drugs that should at the very least slow aging and maybe even "cure" it.  I expect within about 50 years at least humans will have lifespans twice as long as what they are now.  BTW oxidation contributes to aging but I dont know if it actually causes it.
Last edited by A-L-E-X on 20 Nov 2018 23:45, edited 1 time in total.
 
A-L-E-X
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

20 Nov 2018 23:26

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:

Image



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.

Thanks Wat for this very elegant explanation!  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.  In the duo-universe I envisioned, using the perspective of either universe, it's always the other universe that's "FTL" and the properties include that the more energy you apply to an object in motion the slower it goes.  In other words, the speed of light is the asymptotic limit for each universe, but for one it is a lower bound and for the other it is the upper bound. Which is which depends on your perspective, (as does the arrow of time), in the universe we are in light will always be the upper bound, and time will always move forward, for the residents of the other universe, likewise.  And also likewise, it's always the other universe that will appear to be tachyonic with time moving in reverse (even though in reality it's moving forward in both universes, it's just that forward means different directions for each universe.)

------------------

This whole bird thing got me thinking about those huge ancient Terror Birds that used to walk the earth.  The funny thing is they are also mentioned in mythology- didn't one of Hercules' labors involve killer birds?  Stymphalian Birds!  The only contemporary birds that can kill humans I can think of are cassowaries- they have a lethal kick  ;)

Wat I love thermodynamics too!  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.
 
User avatar
Watsisname
Science Officer
Science Officer
Posts: 1752
Joined: 06 Sep 2016
Location: Bellingham, WA

Science and Astronomy Questions

21 Nov 2018 01:47

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.  

Image

Image

Image


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.
 
User avatar
Stellarator
World Builder
World Builder
Posts: 874
Joined: 10 Jul 2018
Location: Sagittarius A*

Science and Astronomy Questions

21 Nov 2018 01:53

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:D) 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:
Image


BTW, have you ever heard of the Kea parrot? They are another modern-dinosaur analog.
Image
 

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.

Image

Of interest:
Futurum Fusionem
 
A-L-E-X
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

21 Nov 2018 03:53

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.  

Image

Image

Image


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.

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.
About the big crunch causing a re-expansion, 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.  Perhaps this is what causes the expansion.

The late great Stephen Hawking was able to deal with the singularity (which resembles black hole singularities and thus why we have black hole cosmology) by constructing a second dimension of time perpendicular to ours called Imaginary Time.  With this second axis of time we can properly treat the big bounce and remove any singularities.

The weird nonzero value of the Cosmological Constant may also be a sign of this- its value might be decreasing with each iteration of the cycle.  And there seem to be issues with the inflationary model that it helps resolve, and Alan Guth himself has become one of its proponents, as well as a few others like Lee Smolin (who also favors quantum selection of universes, and the idea that universes evolve from black holes through evolutionary mechanisms to favor the existence of life.)

I'm also intrigued by the idea that there were certain features found in the Planck satellite analysis of the CMBR that indicate that our universe may have interacted with other universes during its expansion- perhaps something like this eventually will cause its contraction/deflation and big bounce.  Penrose came up with an interesting theory called Conformal Cyclic Cosmology.
 
A-L-E-X
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

21 Nov 2018 04:13

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:D) 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:
Image


BTW, have you ever heard of the Kea parrot? They are another modern-dinosaur analog.
Image
 

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.

Image

Of interest:

Thats very intriguing, because not only were dinosaurs huge back then, so were insects and many many other creatures!  I always thought it was linked to the atmosphere in some way that everything was larger back then.
About the intelligence of animals (we of course are also animals), I dont think we can compare them with each other- it's like different languages.  Dolphins may be more intelligent than humans in some ways.  All these complex animals however show emotions, and dolphins have even been known to save humans.  I remember seeing videos about famous cases where lions, tigers and bears who grew up together viewed each other as brothers and even visited the gravesite of the lion and the monument erected to him (he was the first to die.)  There are also known cases of animals adopting the young of other animals and gorillas like Koko taking on a cat as a pet, and taking care of the cat, painting it in portraits, and grieving when the cat passed on.  Koko communicated in sign language and told of her grief and love for the cat, similarly to how ALEX used to say I love you be good to his trainer every night before going to sleep.  Even ants have pets they keep on farms- they milk aphids and farm fungus ;-)  Bowerbirds where males paint houses for the females and Galapagos finches who use twigs to poke for insects are other examples.

And I remembered a great story about elephant cognition I saw on Nature.  A mama elephant saw poachers kill her baby and drag away the carcass and she followed them for 20 miles and while they were asleep she went back and got her baby and didn't hurt the hunters and took her baby back home and buried her.  In ways like that I actually consider these animals to be better than humans and would definitely value their lives over those of poachers or anyone who hurts any animal.

These highly cognitive animals all share a similar structure in the brain- I think its called mirror neurons?

About dinosaurs, perhaps raptors were the most intelligent.  They hunted in packs like dogs and had stereoscopic vision and would need a complex brain to process all that sensory information.

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.

Particularly intriguing is when animals that are supposed to be natural enemies or predator-prey actually grow up together and treat each other like family.  In some ways I find these other animals treat each other far better than humans do.  And definitely far better than humans treat animals.
 
User avatar
Watsisname
Science Officer
Science Officer
Posts: 1752
Joined: 06 Sep 2016
Location: Bellingham, WA

Science and Astronomy Questions

21 Nov 2018 05:26

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
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

21 Nov 2018 18:30

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.

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.  I posted the name of a cosmologist and some of her work- she teaches at UNC-Charlotte.  Also, how do you feel about Stephen Hawking's Imaginary Time and how he views the universe as being the result of a previously contracting one?  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?

https://en.wikipedia.org/wiki/Big_Bounce#History

Please read this section, there have been some new developments as of 2017.  I also found the footnotes very useful.  It also mentions gravity being repulsive at the singularity level.

Here is one of the papers:

https://arxiv.org/pdf/1304.3122.pdf

another

https://arxiv.org/pdf/1603.05834.pdf


About lack of gravitational waves in 2D

https://www.quora.com/Is-there-gravity- ... l-universe
No, there's not, at least in the traditional sense.  Einsteins equations in 2 spatial dimensions simplify in the case of a local vacuum to 
Rijkl=0 for i,j,k,l∈{t,x,y}.
In words, the local curvature is zero wherever there isn't any matter, and so there is no propagation of the gravitational force, and two separated objects will not attract.

Doesn't general relativity break down at that level, which is why it outputs singularity solutions?
 
User avatar
Stellarator
World Builder
World Builder
Posts: 874
Joined: 10 Jul 2018
Location: Sagittarius A*

Science and Astronomy Questions

21 Nov 2018 20:16

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.
Futurum Fusionem
 
User avatar
Watsisname
Science Officer
Science Officer
Posts: 1752
Joined: 06 Sep 2016
Location: Bellingham, WA

Science and Astronomy Questions

21 Nov 2018 21:55

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.

Well, that is simply not correct.  They could have formed by direct collapse of gas disks to black holes in the ~104 to 106 solar mass range, in the few million years after the Big Bang.  Maybe even other mechanisms that people haven't thought of or worked out rigorously yet.

What we have are a set of models for how black holes form by conventionally understood means.  Those models indeed do not predict black holes to form as early as we observe now.  So we look to the possibility of other mechanisms for black holes to form earlier than we thought.  The period between the Big Bang and the first observed quasars is a lot of time. There was a lot of material available.  It's absurd to insist that the only possible explanation is that they were always there since before the Big Bang!

I compare it to observing a pulsar before understanding the physics of degenerate neutrons, and concluding that because we can't explain such an object, therefore it must be aliens!


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?

That solution does not support our universe being cyclical.  It showed what a cyclical universe would behave like according to the Friedmann equations, if such a universe existed.  As I said in that post, the requirements for that model were quite unphysical.  To make it occur, I had to introduce a substance that dilutes as fast as radiation but has negative energy density.  We have never observed anything that behaves that way.  Our universe is also filled with a dark energy with an equation of state that prevents it from recollapsing, and the constraints on that being true are very good.  So the probability that cyclic solution describes our universe is effectively zero.  

The model that best describes the observed evolution of our universe is the Lambda-CDM model, which I showed in the 2nd section of my post here.


Shortly after showing the cyclical model, I also showed how universes naturally evolve toward dominance by substances with smaller equations of state (w), by virtue of how equation of state determines both how a substance is diluted by expansion and how it affects expansion.  Substances with larger equations of state slow the expansion faster but dilute away more quickly, while substances with smaller equations of state slow it less quickly, or even accelerate it, if w<-1/3.

This property predicts that a generalized universe containing any assortment of substances obeying the Friedmann equations will either collapse on itself (if the density of substances with large w is great enough compared to those with small w), or expand forever (if the opposite).  There is not a large volume "in parameter space" for other behavior to occur.  In a sense that makes the cyclical universes much more interesting, because it is a more exotic solution from the parameter space.

By the measurements of the cosmological parameters, we seem to be in a "expand forever" type of universe, growing to dominance by something with w=-1, which leads to exponential expansion.
 
A-L-E-X
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

22 Nov 2018 00:35

The value of w is interesting, because in one of the cyclic models you actually need a value of w close to -1 for the universe to be cyclic.  

This one:

The Baum–Frampton model
This more recent cyclic model of 2007 makes a different technical assumption concerning the equation of state of the dark energy which relates pressure and density through a parameter w.[7][10] It assumes w < −1 (a condition called phantom energy) throughout a cycle, including at present. (By contrast, Steinhardt–Turok assume w is never less than −1.) In the Baum–Frampton model, a septillionth (or less) of a second (i.e. 10−24 seconds or less) before the would-be Big Rip, a turnaround occurs and only one causal patch is retained as our universe. The generic patch contains no quark, lepton or force carrier; only dark energy – and its entropy thereby vanishes. The adiabatic process of contraction of this much smaller universe takes place with constant vanishing entropy and with no matter including no black holes which disintegrated before turnaround.

The idea that the universe "comes back empty" is a central new idea of this cyclic model, and avoids many difficulties confronting matter in a contracting phase such as excessive structure formation, proliferation and expansion of black holes, as well as going through phase transitions such as those of QCD and electroweak symmetry restoration. Any of these would tend strongly to produce an unwanted premature bounce, simply to avoid violation of the second law of thermodynamics. The surprising w < −1 condition may be logically inevitable in a truly infinitely cyclic cosmology because of the entropy problem. Nevertheless, many technical back up calculations are necessary to confirm consistency of the approach. Although the model borrows ideas from string theory, it is not necessarily committed to strings, or to higher dimensions, yet such speculative devices may provide the most expeditious methods to investigate the internal consistency. The value of w in the Baum–Frampton model can be made arbitrarily close to, but must be less than, −1.

In this model it's actually dark energy that makes the universe cyclical.

I also found this fascinating from Roger Penrose:


The conformal cyclic cosmology (CCC) is a cosmological model in the framework of general relativity, advanced by the theoretical physicists Roger Penrose and Vahe Gurzadyan.[1][2][3] In CCC, the universe iterates through infinite cycles, with the future timelike infinity of each previous iteration being identified with the Big Bang singularity of the next.[4] Penrose popularized this theory in his 2010 book Cycles of Time: An Extraordinary New View of the Universe.


Contents
1 Basic construction
2 Physical implications
3 Empirical tests
4 CCC and the Fermi paradox
5 See also
6 References
7 External links
Basic construction
Penrose's basic construction[5] is to connect a countable sequence of open Friedmann–Lemaître–Robertson–Walker metric (FLRW) spacetimes, each representing a big bang followed by an infinite future expansion. Penrose noticed that the past conformal boundary of one copy of FLRW spacetime can be "attached" to the future conformal boundary of another, after an appropriate conformal rescaling. In particular, each individual FLRW metric {\displaystyle g_{ab}} g_{ab} is multiplied by the square of a conformal factor {\displaystyle \Omega } \Omega  that approaches zero at timelike infinity, effectively "squashing down" the future conformal boundary to a conformally regular hypersurface (which is spacelike if there is a positive cosmological constant, as is currently believed). The result is a new solution to Einstein's equations, which Penrose takes to represent the entire universe, and which is composed of a sequence of sectors that Penrose calls "aeons".

Physical implications
The significant feature of this construction for particle physics is that, since bosons obey the laws of conformally invariant quantum theory, they will behave in the same way in the rescaled aeons as in their former FLRW counterparts (classically, this corresponds to light-cone structures being preserved under conformal rescaling). For such particles, the boundary between aeons is not a boundary at all, but just a spacelike surface that can be passed across like any other. Fermions, on the other hand, remain confined to a given aeon, thus providing a convenient solution to the black hole information paradox; according to Penrose, fermions must be irreversibly converted into radiation during black hole evaporation, to preserve the smoothness of the boundary between aeons.

The curvature properties of Penrose's cosmology are also convenient for other aspects of cosmology. First, the boundary between aeons satisfies the Weyl curvature hypothesis, thus providing a certain kind of low-entropy past as required by statistical mechanics and by observation. Second, Penrose has calculated that a certain amount of gravitational radiation should be preserved across the boundary between aeons. Penrose suggests this extra gravitational radiation may be enough to explain the observed cosmic acceleration without appeal to a dark energy matter field.

Empirical tests
In 2010, Penrose and Vahe Gurzadyan published a preprint of a paper claiming that observations of the cosmic microwave background (CMB) made by the Wilkinson Microwave Anisotropy Probe (WMAP) and the BOOMERanG experiment contained an excess of concentric circles compared to simulations based on the standard Lambda-CDM model of cosmology, quoting a 6-sigma significance of the result.[6] However, the statistical significance of the claimed detection has since been disputed. Three groups have independently attempted to reproduce these results, but found that the detection of the concentric anomalies was not statistically significant, in that no more concentric circles appeared in the data than in Lambda-CDM simulations.[7][8][9][10]

The reason for the disagreement was tracked down to an issue of how to construct the simulations that are used to determine the significance: The three independent attempts to repeat the analysis all used simulations based on the standard Lambda-CDM model, while Penrose and Gurzadyan used an undocumented non-standard approach.[11]

In 2013 Gurzadyan and Penrose published the further development of their work introducing a new method they termed the "sky-twist procedure" (not based on simulations) in which WMAP data is directly analysed;[3] in 2015, they published the results of Planck data analysis confirming those of WMAP, including the inhomogeneous sky distribution of those structures.[12]

In a paper published on August 6th, 2018 Daniel An, Krzysztof Antoni Meissner and Penrose presented a continued analysis of the CMB data as it seemed to them that “…anomalous points provide an important new input to cosmology, irrespective of the validity of CCC.” They also suggest that those anomalies could be what in CCC are Hawking points i.e. remnant signals from “…Hawking evaporation of supermassive black holes in the aeon prior to ours” and claim that a B-mode location found by the BICEP2 team is exactly at one of these Hawking point as predicted by CCC.[13]

CCC and the Fermi paradox
In 2015 Gurzadyan and Penrose also discussed the Fermi paradox, the apparent contradiction between the lack of evidence but high probability estimates for the existence of extraterrestrial civilizations. Within conformal cyclic cosmology, the cosmic microwave background provides the possibility of information transfer from one aeon to another, including of intelligent signals within information panspermia concept.[12]



I need to pick up that book by Penrose.  As you can see I dont like conventional lines of thinking and I've found Penrose's work brilliant (as is Brian Greene who talks about space and time breaking down on the subplanck level)- there is something intellectually stimulating about reading this.
 
A-L-E-X
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

22 Nov 2018 00:54

Interesting problems with the observed value of the Cosmological constant

https://en.wikipedia.org/wiki/Cosmologi ... eld_theory


https://en.wikipedia.org/wiki/Lambda-CD ... Challenges


It has been argued that the ΛCDM model is built upon a foundation of conventionalist stratagems, rendering it unfalsifiable in the sense defined by Karl Popper.[12]

What I like about Penrose's idea is it actually explains why the Big Bang happened and what could actually have existed before then.

Hawking's imaginary time also elegantly deals with the singularity problem

https://en.wikipedia.org/wiki/Imaginary_time

Also while reading the above I found this about causality which you might find interesting

https://en.wikipedia.org/wiki/Delayed-c ... ocausality

In addition to challenging our common-sense ideas of temporal sequence in cause and effect relationships, this experiment is among those that strongly attack our ideas about locality, the idea that things cannot interact unless they are in contact, if not by being in direct physical contact then at least by interaction through magnetic or other such field phenomena.[22]:199

Against consensus
Despite Eberhard's proof, some physicists have speculated that these experiments might be changed in a way that would be consistent with previous experiments, yet which could allow for experimental causality violations.[25][26][27]
 
A-L-E-X
Star Engineer
Star Engineer
Posts: 1670
Joined: 06 Mar 2017

Science and Astronomy Questions

22 Nov 2018 00:57

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.

Mobbing!  That sounds like what crows are observed to do!  Were raptors not considered as intelligent as crows?  I know magpies, which are related to crows, are one of the few species that can recognize their reflections as being reflections.

I saw very interesting behavior by crows once.  A group of children were trying to bring down a crows nest by tossing rocks at it and the crow went to a construction site, grabbed a long metal rod and brought it back and dropped it near the children and made them scatter lol.

Who is online

Users browsing this forum: No registered users and 1 guest