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Hubble deep field image
http://www.youtube.com/watch?v=fgg2tpUVbXQ
The fact that we know stuff like this, and how it looks
http://multimedia.mcb.harvard.edu/anim_innerlife.html
That we can photograph individual atoms and electrons
http://blogs.nature.com/news/thegreatbeyond/2009/09/electron_clouds_seeing_is_beli.html
http://gizmodo.com/5346964/ibm-takes-first-3d-image-of-atomic-bonds
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New <dne### [at] san rrcom> wrote:
> Hubble deep field image
> http://www.youtube.com/watch?v=fgg2tpUVbXQ
>
> The fact that we know stuff like this, and how it looks
> http://multimedia.mcb.harvard.edu/anim_innerlife.html
>
> That we can photograph individual atoms and electrons
>
http://blogs.nature.com/news/thegreatbeyond/2009/09/electron_clouds_seeing_is_beli.html
> http://gizmodo.com/5346964/ibm-takes-first-3d-image-of-atomic-bonds
They're all pretty incredible. I'm most interested in 1, 3, and 4, but I don't
think you can rank them, since any ranking would only reflect your personal
interests. That said, I also found this pretty incredible (46a/08):
http://www.eso.org/public/outreach/press-rel/pr-2008/phot-46-08.html
- Ricky
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"triple_r" <nomail@nomail> wrote:
> http://www.eso.org/public/outreach/press-rel/pr-2008/phot-46-08.html
It seems the video links have gone bad. How about this instead:
http://www.youtube.com/watch?v=0Hmv-6qLM8Y
- Ricky
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Darren New <dne### [at] sanrrcom> wrote:
> Hubble deep field image
> http://www.youtube.com/watch?v=fgg2tpUVbXQ
>
> The fact that we know stuff like this, and how it looks
> http://multimedia.mcb.harvard.edu/anim_innerlife.html
>
> That we can photograph individual atoms and electrons
>
http://blogs.nature.com/news/thegreatbeyond/2009/09/electron_clouds_seeing_is_beli.html
> http://gizmodo.com/5346964/ibm-takes-first-3d-image-of-atomic-bonds
Let's face it, while Hubble kicks much ass, it's pretty much just a huge,
close-to-perfect lens. In other words, a device to form images by capturing
light and expanding it. Not nearly as awesome as a device to measure particles
much smaller than lightwaves and translate those measurements into images... :D
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"nemesis" <nam### [at] gmailcom> wrote:
> Let's face it, while Hubble kicks much ass, it's pretty much just a huge,
> close-to-perfect lens. In other words, a device to form images by capturing
> light and expanding it. Not nearly as awesome as a device to measure particles
> much smaller than lightwaves and translate those measurements into images... :D
I guess you can look at it in a number of ways. I was thinking about the
physical processes and our knowledge of them. From that standpoint, they're
pretty equally awesome, if you ask me. From an engineering standpoint, though,
I would agree. Atomic force microscopes are a lot cooler than a big,
imperfectly polished mirror. It's pretty incredible that atoms can image atoms
at a subatomic level.
- Ricky
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Darren New wrote:
>
http://blogs.nature.com/news/thegreatbeyond/2009/09/electron_clouds_seeing_is_beli.html
>
> http://gizmodo.com/5346964/ibm-takes-first-3d-image-of-atomic-bonds
That first link is totally awesome! The second one is very cool, too.
But to actually "see" the orbitals of an atom is incredible.
--
~Mike
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Darren New wrote:
> http://multimedia.mcb.harvard.edu/anim_innerlife.html
This makes my AthlonXP 1700+ cry.
> That we can photograph individual atoms and electrons
>
http://blogs.nature.com/news/thegreatbeyond/2009/09/electron_clouds_seeing_is_beli.html
Uh... why are the orbitals such weird shapes?
> http://gizmodo.com/5346964/ibm-takes-first-3d-image-of-atomic-bonds
Mmm, blurry. :-D
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triple_r wrote:
> They're all pretty incredible. I'm most interested in 1, 3, and 4, but I don't
> think you can rank them, since any ranking would only reflect your personal
> interests.
Well sure. #2 amazes me not so much because that's how it works (altho
that's pretty awesome), but that we can figure out how it works, and what it
looks like. It's not like you can actually see it going. You have to have
enough theory to deduce this by (say) mixing chemicals together and seeing
what color they turn, and stuff like that.
> http://www.eso.org/public/outreach/press-rel/pr-2008/phot-46-08.html
I'm pretty amazed it only takes 16 years to watch long enough to see
something orbiting the galaxy. :-)
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New wrote:
> I'm pretty amazed it only takes 16 years to watch long enough to see
> something orbiting the galaxy. :-)
On what day of the week did God create black holes? :-)
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Invisible wrote:
> Darren New wrote:
>> That we can photograph individual atoms and electrons
>>
http://blogs.nature.com/news/thegreatbeyond/2009/09/electron_clouds_seeing_is_beli.html
>
>
> Uh... why are the orbitals such weird shapes?
>
Wave functions. The orbital isn't where the electron actually is, just
where it is statistically likely to be. For the math that just goes
right over my head, I found
http://en.citizendium.org/wiki/Atomic_orbital to be readable.
I still am not sure which stuns me more: that those pictures come out
looking close enough to the existing models, suggesting that we got it
right; or that there are just enough things wrong that we may have to
replace the whole model. Either way, the pictures are amazing.
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"Darren New" <dne### [at] sanrrcom> a écrit dans le message de news:
4ab3b553$1@news.povray.org...
> Darren New wrote:
>> I'm pretty amazed it only takes 16 years to watch long enough to see
>> something orbiting the galaxy. :-)
>
> On what day of the week did God create black holes? :-)
>
When He got to go to Loo
Marc
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Darren New <dne### [at] sanrrcom> wrote:
> http://www.youtube.com/watch?v=fgg2tpUVbXQ
The video posits that life in other planets is likely due to the humongous
amounts of stars and planets out there. On the other hand, the opposite
hypothesis is scientifically sound as well:
http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
In short, the hypothesis states that life requires such ideal conditions
that most planets, and even most galaxies simply don't provide them.
The volume inside a galaxy in which any kind of life could possibly form
is quite small. If a star is too close to the core of the galaxy, radiation
will be too high, as well as the density of stars and other objects (which
greatly increases the likelihood of catastrophic events terminating any
possible life-producing conditions). Too far away from the core, and the
metallicity of star systems will be too low to produce any planets which
could produce life.
The shape and other features of the galaxy matter too. Some shapes make
it less likely for habitable conditions to form (because the above problems
will appear throughout the entire galaxy, among other things). This would
mean that only a small portion of all galaxies could support life of any
kind. It also means that most if not all early galaxies in the history of
the universe were inhospitable, and thus it's not very probable for life
to have been formed any time soon after the big bang.
Even inside the "habitable zone" the conditions must be very ideal.
A double star (which is relatively common) will be detrimental to any life.
Even single stars will require other conditions to be life-friendly (such
as having giant gass planets at an appropriate distance which vacuum the
stellar system from dangerous, life-terminating objects). The star itself
must be of a certain type: Too big or too small, too hot or too cold, or
too much radiation, and it will be unfriendly to life.
A planet must have certain conditions to produce life. Too close to the
star, and it won't have any water or other liquids (which is most probably
a prerequisite for life). Too far, and the water will be frozen. Also, the
orbit of the planet must be almost circular for this same reason.
A moon which causes tides, and plate tectonics also help in the process
of life forming. Even if a planet is otherwise ideal, if it lacks those,
it will be much less likely for life to form.
There are a big bunch of other conditions which must also be just right,
or else life will be much less likely. The video calls the Sun "unremarkable",
but in one thing it's extremely remarkable: It's probably one of the very
few stars in the galaxy, if not the entire universe, which has all the
necessary conditions for life.
A common concept is that the universe must be full of life, but that's
not necessarily so. Life might be extremely rare. Intelligent life even
rarer. (The conditions necessary to produce intelligent life make this
whole situation even more complicated.)
--
- Warp
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Warp escreveu:
> Darren New <dne### [at] sanrrcom> wrote:
>> http://www.youtube.com/watch?v=fgg2tpUVbXQ
>
> The video posits that life in other planets is likely due to the humongous
> amounts of stars and planets out there. On the other hand, the opposite
> hypothesis is scientifically sound as well:
>
> http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
>
> In short, the hypothesis states that life requires such ideal conditions
> that most planets, and even most galaxies simply don't provide them.
>
> The volume inside a galaxy in which any kind of life could possibly form
> is quite small. If a star is too close to the core of the galaxy, radiation
> will be too high, as well as the density of stars and other objects (which
> greatly increases the likelihood of catastrophic events terminating any
> possible life-producing conditions). Too far away from the core, and the
> metallicity of star systems will be too low to produce any planets which
> could produce life.
>
> The shape and other features of the galaxy matter too. Some shapes make
> it less likely for habitable conditions to form (because the above problems
> will appear throughout the entire galaxy, among other things). This would
> mean that only a small portion of all galaxies could support life of any
> kind. It also means that most if not all early galaxies in the history of
> the universe were inhospitable, and thus it's not very probable for life
> to have been formed any time soon after the big bang.
>
> Even inside the "habitable zone" the conditions must be very ideal.
> A double star (which is relatively common) will be detrimental to any life.
> Even single stars will require other conditions to be life-friendly (such
> as having giant gass planets at an appropriate distance which vacuum the
> stellar system from dangerous, life-terminating objects). The star itself
> must be of a certain type: Too big or too small, too hot or too cold, or
> too much radiation, and it will be unfriendly to life.
>
> A planet must have certain conditions to produce life. Too close to the
> star, and it won't have any water or other liquids (which is most probably
> a prerequisite for life). Too far, and the water will be frozen. Also, the
> orbit of the planet must be almost circular for this same reason.
>
> A moon which causes tides, and plate tectonics also help in the process
> of life forming. Even if a planet is otherwise ideal, if it lacks those,
> it will be much less likely for life to form.
>
> There are a big bunch of other conditions which must also be just right,
> or else life will be much less likely. The video calls the Sun "unremarkable",
> but in one thing it's extremely remarkable: It's probably one of the very
> few stars in the galaxy, if not the entire universe, which has all the
> necessary conditions for life.
>
> A common concept is that the universe must be full of life, but that's
> not necessarily so. Life might be extremely rare. Intelligent life even
> rarer. (The conditions necessary to produce intelligent life make this
> whole situation even more complicated.)
carbon-based life.
--
a game sig: http://tinyurl.com/d3rxz9
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nemesis <nam### [at] gmailcom> wrote:
> carbon-based life.
Has any form of (intelligent) complex life which is not based on chemistry
similar to our own, and/or which is not heavily dependent on water, been
even seriously conjectured?
Complex life (ie. anything more complicated than something resembling a
virus) requires certain molecular structures, which in turn require certain
chemistry and certain chemical elements to appear in certain proportions.
For example, anything even remotely resembling proteins requires molecules
with certain structures and certain elements to be stable and feasible. If
these elements are not abundant enough, such complex molecules simply cannot
form.
AFAIK, it's physically impossible to get anything even remotely usable
for forming complex life from hydrogen and helium alone. This rules out
most star systems on the outer edges of galaxies, as well as most stars
in galaxies of certain type, for instance.
Also even non-carbon-based life won't survive a collision with an
enormous celestial body. No matter how exotic your lifeforms are, they
will most probably not survive if their planet collides with a star. Thus
star density in the galaxy is a key factor. (While direct collisions might
be less likely, close encounters may well fling the planet out of its orbit,
dooming any potential life to a slow death. You most probably can't have life
at 3 kelvin.)
--
- Warp
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Warp schrieb:
>
> A moon which causes tides, and plate tectonics also help in the process
> of life forming. Even if a planet is otherwise ideal, if it lacks those,
> it will be much less likely for life to form.
This is something that I find particularly intriguing about the place we
live on:
Not the fact that the earth does have a moon. Nor the fact that it is
the only one the earth does have. Not even the remarkable fact that it's
an incredibly huge chunk of rock for such a small planet.
No, what's most astonishing about this all is that its apparent size
matches so well with that of the sun.
I can only think of two possible conclusions for this:
(a) It may be due to the anthropic principle, i.e. there might be some
hidden mechanism in the creation of intelligent life that requires this
extraordinary property.
(b) It was /designed/ to be this way.
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Warp wrote:
> nemesis <nam### [at] gmailcom> wrote:
>> carbon-based life.
>
> Has any form of (intelligent) complex life which is not based on chemistry
> similar to our own, and/or which is not heavily dependent on water, been
> even seriously conjectured?
>
> Complex life (ie. anything more complicated than something resembling a
> virus) requires certain molecular structures, which in turn require certain
> chemistry and certain chemical elements to appear in certain proportions.
Carbon-based complex life certainly. ;)
Fact is we're used to what we're used to. We've never seen any other
life, carbon-based or not. BTW, this conversation just reminds me of
the XKCD strip of today someone posted here.
> For example, anything even remotely resembling proteins requires molecules
> with certain structures and certain elements to be stable and feasible. If
> these elements are not abundant enough, such complex molecules simply cannot
> form.
Reality is quite different inside neutron stars. There is the
possibility of giant earth-like worlds made of hot ice. If
self-replicating organisms would evolve in some of these environments,
how'd they turn out to be made of?
not really suggesting life would be possible inside stars, just
enumerating the weird places this universe has got...
> Also even non-carbon-based life won't survive a collision with an
> enormous celestial body. No matter how exotic your lifeforms are, they
> will most probably not survive if their planet collides with a star.
But they could send their last child to a world with a yellow sun! ;)
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clipka <ano### [at] anonymousorg> wrote:
> Warp schrieb:
> >
> > A moon which causes tides, and plate tectonics also help in the process
> > of life forming. Even if a planet is otherwise ideal, if it lacks those,
> > it will be much less likely for life to form.
>
> This is something that I find particularly intriguing about the place we
> live on:
>
> Not the fact that the earth does have a moon. Nor the fact that it is
> the only one the earth does have. Not even the remarkable fact that it's
> an incredibly huge chunk of rock for such a small planet.
>
> No, what's most astonishing about this all is that its apparent size
> matches so well with that of the sun.
>
> I can only think of two possible conclusions for this:
>
> (a) It may be due to the anthropic principle, i.e. there might be some
> hidden mechanism in the creation of intelligent life that requires this
> extraordinary property.
>
> (b) It was /designed/ to be this way.
(c) Lucky coincidence, since it did not and will not always appear to be the
same size of the sun.
-Reactor
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Warp wrote:
> nemesis <nam### [at] gmailcom> wrote:
>> carbon-based life.
>
> Has any form of (intelligent) complex life which is not based on chemistry
> similar to our own, and/or which is not heavily dependent on water, been
> even seriously conjectured?
Silicon, yes. Same column as carbon.
In any case, it's hard to say what life needs to survive, with only one
sample planet. Oxygen killed almost all the life, and now life flourishes
with it. We have worms living in the bottom of the ocean off sulphuric
vents. Etc.
I don't think we'll know one way or another until we either get out there,
or we build spectroscopes that can analyze the atmospheres of rocky planets
around other stars.
> AFAIK, it's physically impossible to get anything even remotely usable
> for forming complex life from hydrogen and helium alone.
That's probably true. :-)
> Also even non-carbon-based life won't survive a collision with an
> enormous celestial body.
I think if you had life on Jupiter, it could probably withstand quite a
whack. Not a star or a black hole, perhaps.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Reactor schrieb:
> (c) Lucky coincidence, since it did not and will not always appear to be the
> same size of the sun.
Quite mind-bogglingly unlike for intelligent life to "wake up" just at
such a time when it does.
(BTW, are you sure it will not? After all, not only does the lunar orbit
around earth change, but also earth's orbit around the sun. Maybe the
two effects will happen to cancel out?)
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nemesis <nam### [at] nospam-gmailcom> wrote:
> Warp wrote:
> > nemesis <nam### [at] gmailcom> wrote:
> >> carbon-based life.
> >
> > Has any form of (intelligent) complex life which is not based on chemistry
> > similar to our own, and/or which is not heavily dependent on water, been
> > even seriously conjectured?
> >
> > Complex life (ie. anything more complicated than something resembling a
> > virus) requires certain molecular structures, which in turn require certain
> > chemistry and certain chemical elements to appear in certain proportions.
> Carbon-based complex life certainly. ;)
Matter-based complex life in general. Complex life requires complex
molecules, and you can't have complex molecules made purely from the first
few elements a star produces, ie. hydrogen and helium.
Coincidentally, the next chemical element a star produces is, surprise
surprise, carbon. After that it only gets more complicated. Carbon is a
rather versatile molecule, besides being abundant in more developed star
systems, which is probably the reason why we are based on it.
(The elements in-between those are not formed in the core of the star at
all, but in supernova explosions, which means that any of the more complex
chemical elements must come from remnants of old supernovas (which might in
turn have been formed from remnants of even older supernovas, and so on).
AFAIK these stars don't tend to form at the edges of galaxies.)
I'd say that if you want complex life which is not carbon-based, the
conditions must be even more ideal than for us, so it's not like it makes
things simpler, but on the contrary, it probably makes life even less
likely.
> > For example, anything even remotely resembling proteins requires molecules
> > with certain structures and certain elements to be stable and feasible. If
> > these elements are not abundant enough, such complex molecules simply cannot
> > form.
> Reality is quite different inside neutron stars.
It's hard to imagine any kind of life (much less intelligent life) forming
on or in a neutron star. Matter density is way too high for any kind of
regular chemical reactions to happen. Molecules cannot form. Heck, even
atoms cannot form (due to temperature and pressure).
--
- Warp
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Warp schrieb:
> Matter-based complex life in general. Complex life requires complex
> molecules, and you can't have complex molecules made purely from the first
> few elements a star produces, ie. hydrogen and helium.
You're forgetting lithium, which - along with hydrogen and helium
(though at a different isotope relation) - is primordial.
>
> Coincidentally, the next chemical element a star produces is, surprise
> surprise, carbon.
Strictly speaking, beryllium is produced first; but only few of it ends
up outside the star, as it will readily be processed further into carbon
even while it is being "bred".
As another "surprise, surprise", part of the carbon is also processed
further already, into - guess what - oxygen!
> After that it only gets more complicated. Carbon is a
> rather versatile molecule, besides being abundant in more developed star
> systems, which is probably the reason why we are based on it.
>
> (The elements in-between those are not formed in the core of the star at
> all, but in supernova explosions, which means that any of the more complex
> chemical elements must come from remnants of old supernovas (which might in
> turn have been formed from remnants of even older supernovas, and so on).
> AFAIK these stars don't tend to form at the edges of galaxies.)
Not precisely: The breeding of some elements as heavy as iron happens
earlier already.
> I'd say that if you want complex life which is not carbon-based, the
> conditions must be even more ideal than for us, so it's not like it makes
> things simpler, but on the contrary, it probably makes life even less
> likely.
While there's some reasonable point to that, the argumentation is
flawed, missing out the fact that during the formation of planets (and
even stellar systems as a whole) the relation of elements is subject to
additional pyhsical influences, resulting in much different relations
between elements in regions accessible to life. For instance, carbon
makes up for only 0.03% of the mass in earth's crust and atmosphere,
while silicon accounts for some whopping 25% - only surpassed by oxygen
(about 50%).
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Warp wrote:
> It's hard to imagine any kind of life (much less intelligent life) forming
> on or in a neutron star.
Robert Forward wrote some SF novels about that, starting with Dragon's Egg.
He's actually a cutting edge physicist as well, which is pretty cool, so
when he tells you how to put a space ship in orbit around a neutron star
such that you don't wind up being eaten by tidal forces, chances are he
actually did the math. :-)
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > It's hard to imagine any kind of life (much less intelligent life) forming
> > on or in a neutron star.
> Robert Forward wrote some SF novels about that, starting with Dragon's Egg.
> He's actually a cutting edge physicist as well, which is pretty cool, so
> when he tells you how to put a space ship in orbit around a neutron star
> such that you don't wind up being eaten by tidal forces, chances are he
> actually did the math. :-)
Maybe, but let's not forget what the F in SF stands for.
--
- Warp
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Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> Warp wrote:
>>> It's hard to imagine any kind of life (much less intelligent life) forming
>>> on or in a neutron star.
>
>> Robert Forward wrote some SF novels about that, starting with Dragon's Egg.
>> He's actually a cutting edge physicist as well, which is pretty cool, so
>> when he tells you how to put a space ship in orbit around a neutron star
>> such that you don't wind up being eaten by tidal forces, chances are he
>> actually did the math. :-)
>
> Maybe, but let's not forget what the F in SF stands for.
Of course. You said "it's hard to *imagine* any kind of life." ;-) I was
simply pointing you at a fun, interesting book set imaginatively in that
kind of setting. I like sharing book recommendations, since so much out
there is dross it's hard to find good stuff.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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clipka wrote:
> Reactor schrieb:
>> (c) Lucky coincidence, since it did not and will not always appear to
>> be the
>> same size of the sun.
>
> Quite mind-bogglingly unlike for intelligent life to "wake up" just at
> such a time when it does.
>
> (BTW, are you sure it will not? After all, not only does the lunar orbit
> around earth change, but also earth's orbit around the sun. Maybe the
> two effects will happen to cancel out?)
so many unlikely random factors leading to us... ;)
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Warp wrote:
> The video posits that life in other planets is likely due to the humongous
> amounts of stars and planets out there. On the other hand, the opposite
> hypothesis is scientifically sound as well:
>
> http://en.wikipedia.org/wiki/Rare_Earth_hypothesis
>
> In short, the hypothesis states that life requires such ideal conditions
> that most planets, and even most galaxies simply don't provide them.
Wow! I never considered that entire galaxies could be ruled out at
roughly a single glance. That surely reduces the number of possible
Earth-like planets by a large amount.
-Mike
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clipka wrote:
> Quite mind-bogglingly unlike for intelligent life to "wake up" just at
> such a time when it does.
>
> (BTW, are you sure it will not? After all, not only does the lunar orbit
> around earth change, but also earth's orbit around the sun. Maybe the
> two effects will happen to cancel out?)
I think the eccentricity of the Earth's orbit changes over time, not
it's distance. I.e. the Earth's orbit continually oscillates over time
between a more circular and highly elliptical shape. At those times
where the Earth's orbit is highly elliptical, the sun's apparent
diameter might vary noticeably *within a single year* as the seasons change.
-Mike
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SharkD wrote:
> I think the eccentricity of the Earth's orbit changes over time,
The moon is also receeding from the earth due to tidal forces.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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On 09/19/09 13:49, Warp wrote:
> Maybe, but let's not forget what the F in SF stands for.
That F may encompass the whole concept of alien life, if you want to be
picky...
--
No, Taco Bell is NOT the Mexican Phone Company!
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Darren New <dne### [at] sanrrcom> wrote:
> The moon is also receeding from the earth due to tidal forces.
But isn't this recession decelerating? It will stop when the Earth is
tidally locked with the Moon. Thus the Moon is not going to get very much
farther than it already is.
--
- Warp
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Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> The moon is also receeding from the earth due to tidal forces.
>
> But isn't this recession decelerating? It will stop when the Earth is
> tidally locked with the Moon.
I think that's how it usually works. I'm not sure in this case, given that
the sun asserts a greater gravitational influence on the moon than the earth
does.
> Thus the Moon is not going to get very much
> farther than it already is.
I think we have a ways to go before the earth is locked with the moon. :-)
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > Darren New <dne### [at] sanrrcom> wrote:
> >> The moon is also receeding from the earth due to tidal forces.
> >
> > But isn't this recession decelerating? It will stop when the Earth is
> > tidally locked with the Moon.
> I think that's how it usually works. I'm not sure in this case, given that
> the sun asserts a greater gravitational influence on the moon than the earth
> does.
I don't think that's how it works.
The Sun asserts a certain gravitational influence on the Earth-Moon system.
That doesn't affect how the Earth and the Moon influence each other.
If we measure the absolute strength of gravity caused by the Sun, it
might be stronger than the strength of gravity between the Earth and the
Moon, but Sun's gravity is the same for both the Earth and the Moon.
Basically Sun's gravity "sees" the Earth-Moon system as one object.
> > Thus the Moon is not going to get very much
> > farther than it already is.
> I think we have a ways to go before the earth is locked with the moon. :-)
Just a blink, when we are dealing with astronomical times...
--
- Warp
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Warp wrote:
> The Sun asserts a certain gravitational influence on the Earth-Moon system.
> That doesn't affect how the Earth and the Moon influence each other.
If the moon drifts far enough from the earth, the gravity from the sun will
be stronger than the gravity of the earth, so something strange is likely to
happen.
> If we measure the absolute strength of gravity caused by the Sun, it
> might be stronger than the strength of gravity between the Earth and the
> Moon, but Sun's gravity is the same for both the Earth and the Moon.
> Basically Sun's gravity "sees" the Earth-Moon system as one object.
Hmmm. Maybe.
>> I think we have a ways to go before the earth is locked with the moon. :-)
> Just a blink, when we are dealing with astronomical times...
True, but not really a blink when you're dealing with the timespans of
intelligent life on Earth. I've already forgotten what we started out
talking about, tho, so I'm gonna go get more coffee. :-)
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > The Sun asserts a certain gravitational influence on the Earth-Moon system.
> > That doesn't affect how the Earth and the Moon influence each other.
> If the moon drifts far enough from the earth, the gravity from the sun will
> be stronger than the gravity of the earth, so something strange is likely to
> happen.
I'm not a physicist, but I still think you have got some errors in your
thinking.
You seem to think that the Sun exerting a gravitational force on the Moon
larger than the Earth does is somehow significant, but I don't think that's
how it works. In fact, I think it doesn't matter too much whether the Sun's
gravitational pull is stronger or weaker than the Earth's. (The difference
might affect the speed at which things happen, not whether they happen at
all.)
There might be some tidal forces in play, caused by the Sun's gravitational
pull being stronger for the object closer to it (when it is closer to it)
than the other object, which is farther from it, but that doesn't have
anything to do with the Sun's gravitational pull being larger than the
Earth's.
I don't know how strong the tidal forces caused by the Sun are at the
altitude of the Earth-Moon system, but I bet it's not very strong, and
probably won't rip the system apart (or else it would probably have done
so already).
But as said, I'm not a phycisist. A pro could be laughing at me right now
for making such foolish statements. :)
--
- Warp
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Warp wrote:
> I'm not a physicist, but I still think you have got some errors in your
> thinking.
Quite possibly. But look at it this way: Say the altitude of the moon over
the earth was 1000x what it is now, and the moon was orbiting appropriately
slower? What if the outside of the moon's orbit was close to where Venus is?
Certainly there would be different dynamics. Hence, in the limit, there's
obviously some point where the influence of the sun overwhelms the influence
of the earth. I don't know where that point is, mind, or whether it would
occur before or after the planets were tidally locked 100%.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > I'm not a physicist, but I still think you have got some errors in your
> > thinking.
> Quite possibly. But look at it this way: Say the altitude of the moon over
> the earth was 1000x what it is now, and the moon was orbiting appropriately
> slower? What if the outside of the moon's orbit was close to where Venus is?
> Certainly there would be different dynamics. Hence, in the limit, there's
> obviously some point where the influence of the sun overwhelms the influence
> of the earth. I don't know where that point is, mind, or whether it would
> occur before or after the planets were tidally locked 100%.
This sounds a lot like the three-body problem... :P
Anyways, as I said, the recession of the Moon is, AFAIK, decelerating,
and it's quite slow to begin with, so I think the Earth is not going to
lose the Moon ever (unless some external forces come into play to disturb
the whole thing).
--
- Warp
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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > I'm not a physicist, but I still think you have got some errors in your
> > thinking.
> Quite possibly. But look at it this way: Say the altitude of the moon over
> the earth was 1000x what it is now, and the moon was orbiting appropriately
> slower? What if the outside of the moon's orbit was close to where Venus is?
> Certainly there would be different dynamics. Hence, in the limit, there's
> obviously some point where the influence of the sun overwhelms the influence
> of the earth. I don't know where that point is, mind, or whether it would
> occur before or after the planets were tidally locked 100%.
Ah, I found the exact term you are talking about:
http://en.wikipedia.org/wiki/Hill_sphere
--
- Warp
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Interesting tidbit: Did you know that Moon's orbit around the Sun is
completely convex? (In other words, the curvature of the orbit never
changes sign.)
--
- Warp
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Warp wrote:
> Ah, I found the exact term you are talking about:
> http://en.wikipedia.org/wiki/Hill_sphere
Kewl! So if the moon gets close to taking 7 months instead of 1, we could
be in trouble. :-)
I had read in a reliable source that the moon is actually more attracted to
the Sun than the Earth when it's at eclipse, but I never did the math
myself, and I'm too lazy to look at the math here to see if that's
sufficient to disrupt the orbit anyway. :-)
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Warp wrote:
> Interesting tidbit: Did you know that Moon's orbit around the Sun is
> completely convex? (In other words, the curvature of the orbit never
> changes sign.)
Yes, that's what I'd read about. In essence, it's orbiting the sun as it
wobbles back and forth across the earth's orbit, rather than actually
orbiting the earth. That's why I thought we might be much closer to losing it.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > Interesting tidbit: Did you know that Moon's orbit around the Sun is
> > completely convex? (In other words, the curvature of the orbit never
> > changes sign.)
> Yes, that's what I'd read about. In essence, it's orbiting the sun as it
> wobbles back and forth across the earth's orbit, rather than actually
> orbiting the earth. That's why I thought we might be much closer to losing it.
"Rather than actually orbiting the Earth" is incorrect. It *is* orbiting
the Earth. The Earth-Moon system is orbiting the Sun. Ergo the Moon is
*also* orbiting the Sun. In other words, the Moon is orbiting both.
The orbital period of the Moon around the Earth is so slow that if we
trace the Moon's orbit around the Sun, it actually results in a completely
convex shape. However, that's more a curiosity than anything else. It
doesn't mean it's not "actually orbiting the Earth".
--
- Warp
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Warp wrote:
> doesn't mean it's not "actually orbiting the Earth".
Hmmmm. OK. I don't feel like doing the math, but I suspect you're right.
:-) Maybe at some point I'll figure out how much the sun attracts the moon
vs the earth.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Darren New <dne### [at] sanrrcom> wrote:
> I had read in a reliable source that the moon is actually more attracted to
> the Sun than the Earth when it's at eclipse, but I never did the math
> myself, and I'm too lazy to look at the math here to see if that's
> sufficient to disrupt the orbit anyway. :-)
As I have said many times already, the Sun's gravitational pull being
stronger than the Earth's is inconsequential. The Sun's gravitation is
affecting *both* the Moon and the Earth at the same time, as a whole.
They are both "falling" at the same rate. Thus it doesn't really matter
what this rate actually is (at least not at Earth's altitude).
Think of it like this: At midday the Sun's gravitation effect on *you*
is stronger than the Earth's. However, that doesn't mean you are going to
be pulled out of Earth. (The reason is that the same gravitation is *also*
affecting the Earth.) Easier to understand it like this?
--
- Warp
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Warp <war### [at] tagpovrayorg> wrote:
> Think of it like this: At midday the Sun's gravitation effect on *you*
> is stronger than the Earth's. However, that doesn't mean you are going to
> be pulled out of Earth. (The reason is that the same gravitation is *also*
> affecting the Earth.) Easier to understand it like this?
(Ok, I must confess I actually don't know if that's true because I haven't
done the math nor seen others' results on that. However, it could be true
and it wouldn't change anything.)
--
- Warp
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Darren New <dne### [at] sanrrcom> wrote:
> Warp wrote:
> > doesn't mean it's not "actually orbiting the Earth".
> Hmmmm. OK. I don't feel like doing the math, but I suspect you're right.
> :-) Maybe at some point I'll figure out how much the sun attracts the moon
> vs the earth.
I don't really understand why you are so fixated about this Sun vs Earth
gravitation thing.
The Sun is affecting *both* the Earth and the Moon, not the Moon alone.
It's not like the Sun and the Earth were competing with each other to see
which one gets to pull the Moon. It doesn't matter if the Sun's gravitation
is stronger than the Earth's. It makes little difference.
--
- Warp
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Warp wrote:
> It doesn't matter if the Sun's gravitation is stronger than the Earth's.
I'm just having trouble figuring out *why* it doesn't matter. :-)
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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Warp wrote:
> Think of it like this: At midday the Sun's gravitation effect on *you*
> is stronger than the Earth's.
I don't think it is, tho.
> However, that doesn't mean you are going to be pulled out of Earth.
If you go to where the moon's gravity exactly matches the earth's gravity,
in space between the two, you'll not be attracted to either one, right? If
you're ten miles closer to the moon, eventually you'll fall onto the moon.
If you're ten miles closer to the earth, eventually you'll fall onto the earth.
>(The reason is that the same gravitation is *also*
> affecting the Earth.) Easier to understand it like this?
I can see where the mechanics of the orbits would have an effect on it.
Maybe I just need more coffee. Obviously the Sun is not wresting the Moon
away from the Earth, so I'll just have to let it perk a while and see if my
hind-brain can figure out an intuitive-for-me way of understanding it.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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From: Neeum Zawan
Subject: Re: I can't decide which is most awesome
Date: 21 Sep 2009 10:24:30
Message: <4ab78c9e@news.povray.org>
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On 09/20/09 16:05, Darren New wrote:
> If you go to where the moon's gravity exactly matches the earth's
> gravity, in space between the two, you'll not be attracted to either
> one, right? If you're ten miles closer to the moon, eventually you'll
> fall onto the moon. If you're ten miles closer to the earth, eventually
> you'll fall onto the earth.
That's only if you assume no transverse velocity - which is not the
case for the moon.
--
"Eureka!" said Archimedes to the skunk.
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On 09/20/09 12:42, Darren New wrote:
> If the moon drifts far enough from the earth, the gravity from the sun
> will be stronger than the gravity of the earth, so something strange is
> likely to happen.
Actually, it's quite possible that the gravity of the sun is already
greater. At the very least, they're of the same order of magnitude.
--
"Eureka!" said Archimedes to the skunk.
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Neeum Zawan escreveu:
> On 09/19/09 13:49, Warp wrote:
>> Maybe, but let's not forget what the F in SF stands for.
>
> That F may encompass the whole concept of alien life, if you want to
> be picky...
Life itself is so unlikely that it may well be we're all living a big
fiction... :P
--
a game sig: http://tinyurl.com/d3rxz9
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