Showing posts with label Astronomy. Show all posts
Showing posts with label Astronomy. Show all posts

Monday, December 05, 2016

Small stars may have stable Habitable Zones, but habitable planets might not be common there


Protoplanetary accretion disk around a new star
Protoplanetary accretion disk around a new star
The previous article Limited lifespan of Habitable Zones around other stars (September 2016) covered the topic of Habitable Zones for planets around other solar systems.  However, Habitable Zones are only one of considerations for finding other stars with habitable planets.  Given the lack of data right now, sometimes science has to fall back on simulations.  These simulations do not replace actual observations.  Instead, they offer clues as to how we may be proceed in our search for hard data.

Habitable Zones appear to be more stable and longer lasting around small stars, such as Red Dwarfs.[001]  However, what are the chances of habitable planets appearing in these small zones around these small stars?  It turns out that the chances may not be good.

According to the study A Decreased Probability Of Habitable Planet Formation Around Low-Mass Stars, multiple simulations suggest that low-mass stars are unlikely to have terrestrial planets of sufficient size within their Habitable Zones.  This is due to a several factors.  That's not to say it is impossible nor improbable; just not as common as previous thought.[002]

Other factors

Besides Habitable Zones, another factor to consider is the Habitable Planet Mass Limit.  There is evidence that suggests that plate tectonic activity on a global level is a necessary factor for supporting life on a planet similar to Earth.  Planets must be of a particular size in order to allow for global tectonics.[002]  The lack or presence of global tectonics seems to be a factor in the differences between Venus and Earth.  Though Venus seems to be large enough, its surface heals too quickly to allow for global tectonics.[003]   The examples within our own solar system suggest that even when planets are large enough, there is no guarantee they will have global tectonics.

Another factor is the Protoplanetary Disk.  During the planet formation phase (accretion), there has to be enough material within the disk of matter that forms around very young stars (Protoplanetary Disk) in order produce larger planets.  Though there are a lot of unknowns regarding this factor, the "ratio of disk mass to stellar mass is roughly constant with stellar mass".  Also, planets seem to form much faster around small stars for various reasons.  With less time to form and less mass within the Protoplanetary Disk, planets around low-mass stars may typically be much smaller.  A second issue with fast forming planets is that they are much less likely to have enough time to collect enough water to support life.[002]

Exceptions?

Nothing is absolute.  Gliese 581 is a Red Dwarf that has a number of large planets, and also has a debris disk that appears to have tens times amount of comet debris than our own Solar System.  This suggests low-mass stars can have habitable planets.  That said, Gliese 581 may be an outlier.  Other factors are obviously involved that need further study.

Primary reference:
S. N. Raymond, J. Scalo and V. S. Meadows, The Astrophysical Journal 669 (Nov., 2007) 606–614, arXiv:0707.1711 [astro-ph], A Decreased Probability of Habitable Planet Formation around Low-Mass Stars

Response:
Hacker News

Friday, September 09, 2016

Limited lifespan of Habitable Zones around other stars [and a loosely held secret finally revealed about me]

Habitable zone around a red dwarf, image © Matthew Lorono, 2016
Habitable Zone around a Red Dwarf star
I've been fascinated by the idea of planets around other stars since I was young.  In fact, I developed several fictional solar systems, one of which became the basis for an online gaming and science fiction club.  That solar system is called Greeop System,[001]  which inspired the development of many more solar systems and formed the basis of many gaming and fictional story plots.[002]

At some point, I stumbled across the book Rare Earth: Why Complex Life Is Uncommon In The Universe (2000), which is one of the earliest sources that discusses the idea of Habitable Zones around stars.  

What's a Habitable Zone?  If a terrestrial planet orbits its sun at just the right distance, that sun provides the right amount of light and other energy to make life more likely, given several other factors.  If a planet is too close to its sun, it is likely too hot.  If a planet is too far from its sun, it is likely too cold.  This is why Habitable Zones are sometimes called Goldilocks Zones, in reference to the fairy tale Goldilocks and the Three Bears and finding options that are "just right" between two extremes.

In the past decade, the concept of Habitable Zone has been refined.  From the study Habitable Zone Lifetimes of Exoplanets around Main Sequence Stars, it is now often defined similar to,
...the circumstellar distance at which surface temperatures allow liquid water to be present on the planet’s surface, assuming variable H2O/CO2/CH4 greenhouse forcings.  The Habitable Zone has a minimum and maximum extent, forming inner (closer to the star) and outer boundaries that are set in part by biogeochemical climate feedback mechanisms and stellar luminosity.[003]
Yeah, Goldilocks metaphor seems to get the point across easier.  The question is, what's "just right" for life?  Star size and age appear to play the substantial roles in setting the limits of a Habitable Zone.  Not only is the Habitable Zone different between large and small stars, it can move over the life-cycle of a star. For example, main sequence stars gradually output more energy over billions of years.  A planet that initially forms within the Habitable Zone of a young star might not remain in the Habitable Zone later in the star's life-span. It is predicted that our Sun will be so hot in 1.75B years, surface water will no longer be possible on Earth, presumably making life on Earth no longer sustainable.[003]

If a planet has the right conditions and resides within the Habitable Zone, life still has to appear and evolve in some sort of sequence.  Taking Earth as the only example we have,
... this stepwise progression began with the origin of life, continued through the transition from replicating molecules to RNA and then DNA [1B years after Earth formation], from prokaryotes to eukaryotes [1.5 to 2.5B yrs after Earth formation] and cell differentiation [3.5 to 4B yrs after Earth formation], and concluded with the final step from primate to human societies [4.54B years after Earth formation].[003]
However, if just one of these steps takes a lot longer, there is a drastically lessened chance of having enough time to develop intelligent life similar to humans; assuming the march toward more intelligent creatures is inherent to the process of evolution on different planets.  Different stars may also extend or reduce the time-frame within which life may appear and develop.  Larger stars will have short Habitable Zone lifespans.  Smaller stars, such as Red Dwarfs may have very long and stable Habitable Zone lifespans.

Of course, a lot of this is based on assumptions that life on other planets will resemble life that formed on Earth.  Maybe life of different kinds exist in the Universe.[004]  The rules may be different for different kinds of life.  Maybe Earth is extremely unusual. Worse, maybe we will not be able to immediately recognize other forms of life simply because it is so different from our experience.  As more information is gathered, these issues will hopefully be addressed.

Pirmary reference:
Andrew J. Rushby, Mark W. Claire, Hugh Osborn, and Andrew J. Watson. Astrobiology. September 2013, 13(9): 833-849. doi:10.1089/ast.2012.0938, Habitable Zone Lifetimes of Exoplanets around Main Sequence Stars.

Response:
Voat.co

Monday, June 17, 2013

Notion of Creation is not a theory, and scientific theories aren't proposed notions

Bible based knowledge does not lead to new scientific knowledge.  People used to think the Bible was useful to learn about nature.  They did try to use it as a guide to make new discoveries.  However, over time, scientists started finding out that the Bible just gets so much wrong.    The Bible literally has almost every major point wrong about the universe, from its description of Earth as a flat world with a tent over head to its description of rabbits as cud chewers. The value of the Bible is it's a general moral guide taken in the context within the times each portion was originally written/re-written. Taking it for more than that is truly grasping as straws.  People discovered the hard way that the Bible was not a good starting point to learn about nature. That's why the practice of referring to the Bible as a source for science was stopped over time.
So, to that point, Creationism based on the Bible isn't a theory. It is a failed notion. A theory isn't just a proposal. It is a proven working model of the Universe with a lot of peer reviewed data, from which accurate predictions can be made. To extend this further, those predictions often create new areas of exploration and further growth of knowledge, directly leading to new technologies, either in the exploration of the theory or as a result of knowledge learned from the theory. Last major invention spurred by Bible belief was the telescope, and use of that technology disproved that belief; the creator being forced to recant his statements about reality and live under house arrest for the remainder of his life.

On the other hand, Darwin didn't create the Theory of Evolution, he proposed the core concepts based on his observations. Evolution was born out of the peer review process with much more independently collected data. Evolution wasn't a theory until there was a massive amount of data and extraneous amount of analysis of that data, from which the natural model was molded.

Why is Creationism not a theory? Because it doesn't have one iota of this. The supporters want a magical shortcut, using circular arguments and cherrypicked research of other people's works in the form of anecdotes and impressive looking fake equations. No actual proven predictions come from Creationsm nor from its child contrivance called Intelligent Design. Creationism is the end of knowledge, not its birth. That is why is it not a theory and it is not science. Now, that said, the challenge is always there for Creationism supporters to objectively collect data and test hypotheses. Even if they don't prove their hypotheses, at least new knowledge would come from that. This process has yet to be undertaken by Creationist (and Intelligent Design believers), or if it has, results have been hidden.

Examples of observations that would grow knowledge along the Creationist track:
  • Find DNA in mammals that cannot be traced back to a common ancestor or introduced by some other natural process.
  • Show completely distinct lifeforms with no ancestry at all. 
  • Find data that offers new evidence to reinterpret apparent evolution in our own species, from malaria resistance to lactose persistence.
  • Additionally, find data that better explains why pre-agricultural humans did not have cavities and modern humans with no cavities is almost unheard of? (Hint, that has been very well explained with a recent study of mouth-dwelling bacteria and their evolution to adapt to our changing diets, along with our own evolution for such too.)
These examples cannot be explained with anecdotes.  Hard evidence has to be presented from scientific studies using the Scientific Method.  Research doesn't count for this.  New evidence has be presented.  That evidence must be collected and peer reviewed.  Until that happens, Creation Notion can never be put on equal footing with any Scientific Theory, especially the Theory of Evolution.

Saturday, April 06, 2013

Remote Stone

Of what world we wonder true?  Our lacking nature holds fast our corporeal soul upon the bosom of thriving abodes that guise the cradled womb.  In this place stand we, me and all others, bound not in chains but yoked hereto nonetheless.  Grand thrusting spears slice through the wondrous  blue veil, floating on the currents of bent universe beyond this round realm, bringing to the helm  fleshless anthropomorphized cold creatures to cast away the dark cloak, thus revealing remote stone for stone’s sake.

Wednesday, March 21, 2012

Notion: dimensional time eliminates need for branching universes

This post is only going to be a superficial discussion and isn't going to explain anything in any real depth. I'm trying to simplify advanced quantum physics in the best way a "lay" person can.

In 1957, Hugh Everett introduced the idea of branching universes to solve a problem we encountered regarding seemingly random choices that the elements of the universe (waveforms in particular) when observed. Sometimes light appears as a wave, sometimes as a particle, and there is no way to know which a head of time. Everett suggested that the light doesn't make a choice when is it forced into one form or the other. It is always both a wave and a particle. The Universe branches into two each time the light is observed and forced to make a choice. In one Universe, you observe light beam taking on wave behavior. In the other Universe, another-you observes the light take on a particle behavior. Thus, the idea of branching Universes says that a two Universes are created every time a choice like this is made. There's a certain bit of faith required to believe this, but pure math doesn't lie, right?


The challenge
Now, I'm no physicists. I'm not going to challenge the math that goes into this notion. It's been tested many times and found to be sound. However, math is nothing more than a numeric language that we created ourselves to parse out elements of the Universe to understand it in our terms. Keywords being "our terms".

Everett's assertions about branching Universes (or Many-worlds interpretation, as it is formally called) are based on time being both linear and two dimensional at the same time. Each branching Universe is 1 dimensional, created within 2 dimensional time, like branching lines being doodled on a piece of paper. Well, that means it could be said time is 1.5 dimensional. I know many physicists will cringe at my interpretation of branching Universes. However, at least from an intellectual point of view, this seems to me to be a reasonable simplification. My point is the the concept of branching Universes offers an unnecessarily complex and convoluted explanation for something as simple as a beam of light acting one way instead of another.

Spontaneous creation of matter and energy?
Another problem I have with branching Universes is this. Where is all the infinite energy coming from to create all these infinite branches? Infinite energy is the same as infinite mass (E=mc2). If the Universe really started off with all of this infinite energy, it would have immediately collapsed back on itself, never to grow in the first place. Or, if the energy didn't exist at the Big Bang, there's no mechanism now that can continuously double the energy within a Universe to spawn new versions of itself. Thermodynamics has yet to be disproved by quantum physics.

Why is gravity so heavy?
Yet another problem. If gravity exists outside of the Universe, as current understanding quantum physics now suggests, it would be impacted by the creation of new branches of the Universe. As such, even if infinite energy is being created on the fly (as opposed to being there at the start of the Universe), gravity would weaken so rapidly, its decaying influence on this Universe could be readily measured and would likely lead each Universe to fly apart to nothingness shortly after the Big Bang. There wouldn't be enough gravity to form a single dust particle, let alone entire galaxies.

Every point in the Universe knows about every other point, 13 billion light years away?
One more problem? Sure. For entire Universes to be created instantly and constantly by the actions of a single particle or waveform in a highly localized point, every bit of energy, every particle, everything that exists would have to be instantly duplicated. These means that every bit of energy, every particle, everything in existence would have to be in instantaneous communication with every other bit of energy, particle and every object in the Universe, 13 billion light years across! This creates a new problem! If the action of every particle in the Universe has the ability to replicate the entire Universe, the information of the Universe has to be immediately available to all points within the Universe at the same time. But if the Universe is constantly branching, there is no preferred frame of reference from which the Universe can be infinitely replicated! There's no sorting mechanism to give one choice a preference over another when they happen at the same time. This leads to yet another problem.

Branching causes information bottleneck
The very act of infinitely and instantly replicating the Universe would create huge gaps in information on whatever the current state Universe is in. Things happen simultaneously all the time. How are quadrillions of simultaneous actions supposed to be instantly reconciled to instantly form quadrillion x quadrillion Universes? Some suggest that the ends of the Universe (whatever is just beyond 13 billion light years in any direction) may already be out of touch with each other. This would make the Universe impossible to instantly resolve to form all of these simultaneous branches. Even if all information about the Universe is known to all points in the Universe at any given instant, there would be a measurable bottleneck of the branching activity. Time would slow down at an increasingly observable rate.

2D Time makes branching unnecessary anyway
Here's the kicker. If the Universe is 1 dimensionally branching within 2 dimensional time, then time is already considered 2 dimensional. If time is 2 dimensional, then there's no need for the branching to take place. If the Universe is a waveform in 2 dimensional time, the objects within it are smeared across this these two time dimensions. We are simply seeing a 1 dimensional view of our Universe intersecting with 2 dimensional time.

Ball passing through a plane acts the same as our view of time
This is similar to a 3 dimensional ball that passes through 2 dimensional plane. As the ball passes through the plane, an observer on the plane simply sees a line that grows, then shrinks. He doesn't see the ball itself. Depending on where the ball intersects the plane, the observer sees a shorter or longer line (even just a point). Any measurement of the line is just as valid as any other, but only the portion that intersects the plane can be measured at any one time. So, this is also true of the Universe if time is 2 dimensions, and the Universe is a waveform that intersects it at different points.  We simply see different view points of the same event each time we make an observation. There's nothing random about the observations! We just cannot see the whole shape in our limited view!

We aren't creating new branches of the Universe when the Universe "makes a choice". We are simply observing where our Universe is intersected by 2D time!
When we observe something that forces the Universe to "make a choice", it's not random. We are simply observing which portion of our Universe (or the element being observed) is currently intersecting within the 2 dimensional time. This doesn't mean that there aren't parallel Universes that resemble our own. It just means that those Universes have been there since the Big Bang (not branching), using a measurable portion of the Big Bang's energy for their formation, just as our Universe has.

To be clear, I offer the above as a notion to point to other interpretation of Quantum Physics. It's not meant to be the final word on anything, nor does it represent a tightly held belief of my own. I certainly haven't done any math to back any of this up. However, I do believe there are physicists that are already moving along similar paths of reasoning, so I'm trying to get the word out as the concept of branching Universes has been gaining momentum in recent years with very little in the way of observations to back it up.

Sunday, January 15, 2012

Senseless Sunday: skin deep lunacy



  • The next leap year where Feburaury does not have a full moon is 25721.


  • The current definition of the term "Blue Moon" dates back to March 1946, in which Sky and Telescope magizine mistakenly misinterpreted the definition of the term from 1937 Maine Farmers' Almanac. "Blue Moon" originally referred to the third Full Moon in a season which has four Full Moons2.


  • Atheists outnumber all but nine organized religions in the World.


  • The skin of a polar bear is black. Though the fur appears white, it's actually clear.


  • More often, you will use more gas making a left turn than making a right turn.

Saturday, August 14, 2010

Astronaut declares government is hiding evidence of aliens

Astronaut Edgar Mitchell, a member of the 1971 Apollo 14 moon mission, has recently declared last year that the U.S. and other governments are concealing evidence of aliens and UFOs. Mankind has long wondered if we're "alone in the universe. ...only in our period do we really have evidence. No, we're not alone," Mitchell said.

He bases this conclusion because he grew up in Roswell, NM and have had individuals come forward to him that admitted to see some of what was going on with the infamous Roswell crash. When even insiders are coming forward, it is hard to ignore the questions regarding aliens.

Friday, May 21, 2010

Bode's Law

Bode's Law, or Titus-Bode Law, is a now refuted law governing planet location with our Solar System. It presumes a relationship between all of the planets in their distances from the Sun.

Formulation

The Law relates the semi-major axis, a, of each planet outward from the sun in units such that the Earth's semi-major axis = 10, with

a = n + 4
where n = 0, 3, 6, 12, 24, 48 ..., with each value of n > 3 twice the previous value. The resulting values can be divided by 10 to convert them into astronomical units (AU), which would result in the expression

a = 0.4 + 0.3 · 2 m
for m = , 0, 1, 2,...[1]

For the outer planets, each planet is 'predicted' to be roughly twice as far away from the Sun as the next inner object.

Origin

It's name comes from the fact that it was promoted by Johann Elert Bode when in 1768, he wrote the second edition of his astronomical compendium Anleitung zur Kenntniss des gestirnten Himmels, which states the following.
Let the distance from the Sun to Saturn be taken as 100, then Mercury is separated by 4 such parts from the Sun. Venus is 4+3=7. The Earth 4+6=10. Mars 4+12=16. Now comes a gap in this so orderly progression. After Mars there follows a space of 4+24=28 parts, in which no planet has yet been seen. Can one believe that the Founder of the universe had left this space empty? Certainly not. From here we come to the distance of Jupiter by 4+48=52 parts, and finally to that of Saturn by 4+96=100 parts.

History

At the time, Saturn was the farthest known planet. Bode's Law gained credibility when Uranus and then Ceres where discovered. These bodies happened to fall in line with predictions made by the formula. However, this Law become refuted when Neptune was discovered at a location from the Sun that was no where near its predicted location.

Also, to further refute Bode's Law is the fact that other systems exist in our Solar System which do not follow its formula. Although the moons around Jupiter, Saturn and Uranus do follow some sort of pattern, they do not follow Bode's Law; nor do they share patterns with each other.

Status

The discovery of Pluto and more recently other Kuiper Belt objects have proven Bode's Law to be false. It appears that Bode's Law was a misguided attempt to explain an observation that did not have enough data. Given what is known now, it seems that perhaps there is some sort of rule that applies to naturally formed orbiting body systems, but there is no formula that can predict the arraignment of such. Perhaps Bode's Law can be useful in the future, not to predict planet placement in other extrasolar systems, but maybe to point us in the direction to understand planet formation and resonance. We can see there is some sort of resonance. We can also see that a particular resonance is not shared between different systems, and only applies in a limited fashion. It is not useful for anything else. Although it really cannot be called pseudo-science, since it was based on observation and did make some predictions that panned out, it is really not useful science today. Further complicating the issue is that the definition of planet has changed. Ceres and Pluto are no longer considered planets. This means that any use of Bode's Law in the context of what is now known can be called pseudo-science.


Planet Distances from the Sun (from Wikipedia.org)

Mercury factor: 0
Bode’s Law: 0.4, Actual: 0.39

Venus factor: 1
Bode’s Law: 0.7, Actual: 0.72

Earth factor: 2
Bode’s Law: 1.0, Actual: 1.0

Mars factor: 4
Bode’s Law: 1.6, Actual: 1.52

Ceres factor: 8
Bode’s Law: 2.8, Actual: 2.77

Jupiter factor: 16
Bode’s Law: 5.2, Actual: 5.2

Saturn factor: 32
Bode’s Law: 10, Actual: 9.54

Uranus factor: 64
Bode’s Law: 19.6, Actual: 19.2

Neptune factor: 128
Bode’s Law: 38.8, Actual: 30.06

Pluto factor: 256
Bode’s Law: 77.2, Actual: 39.44

Sunday, April 25, 2010

Are Aliens Really Alien?

A question I've asked myself is that what if the beings we call aliens (visitors from other planets) are really not aliens at all, but inhabitants of our own planet. There are several ways for this to be true. The idea of ultraterrestrials and metaterrestrials is not new. However, there , is one more possibility that seems just as likely from a particular perspective.

There is a possibility that we are being visited by beings from the future. This is based on two assumptions. First, the human species will continue to evolve throughout time. Second, time travel is a technology that we will eventually obtain. If these two assumptions are true, then the most likely source of "alien" encounters is actually future evolved human-descended visitors that come back in time to observe their primitive past. They would come back to study us or to see us out of curiosity.

This would be that two major class of visitations would occur: site-seeing and scientific, or tourists and scientists. Almost on a lark to describe this possibility, I coined the term Future Evolved Terrestrial Tourists and Scientists (FETTS).

This would mean that some beings either come back to observe ancients times much in the same way we visit the pyramids or other ancients sites. In fact, there are stories that every president of the U.S. in modern times has seen U.F.O.'s at some point in their life. President Carter himself is even on the record as being a person who has seen one.

This also means that some other beings comes back to experiment on their primitive ancestors, much in the same way that we modern humans experiment on great apes, including climps.

This explanation is actually more likely than others if time travel proves to be easier than space travel. According to current understanding of the Universe, there is no reason as to why time travel shouldn't be allowed; though General Relativity does demonstrate that faster-than-light travel impossible. With this fact, assuming visitations from beyond are real, it seems most likely that these visitations are from our own world.

Friday, December 25, 2009

Possibilities Regarding Zeta Reticuli

A recent book that has come to my attention on the topic of aliens and Zeta Reticuli is FROM ZETA RETICULI TO EARTH. TIME, SPACE, AND THE UFO TECHNOLOGY : Scientific Frontiers of Alien Space Crafts. It's a long name for a book that is so far well reviewed by its readers. According to the publisher, it takes an objective view regarding topics ranging from time travel and UFO phenomena. It should be interesting to see what the author Maximillien De Lafayette has to say about this subject.