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Having read about molecular biology and so forth, I would love to be
able to simulate this kind of thing in a computer. With real organisms,
you have to guess what happened from the evidence that is left today.
With a computer simulation, you could potentially record the entire
history of the whole system.
There's a couple of problems with that though.
One problem is chemistry. In real life, the amino acid sequence of a
protein dictates the way it folds up to make a functional molecule, and
the folded shape dictates what the molecule actually does. But
currently, predicting the way that one single small protein will fold is
a computational problem so crushing that it brings state-of-the-art
supercomputers to their knees. The largest computer cluster in the
world, folding@home, exists to simulate *simplified* protein folding
experiments.
If it takes that much computer power just to calculate the shape of one
single protein, then simulating an entire living cell, consisting of
many hundred trillion protein and other molecules is obviously vastly
infeasible. Simulating a multicellular organism such as a tiny ant is
laughably impossible.
The next problem is the size of a typical genome. According to
Wikipedia, the various genomes that have been sequenced vary from 10 MB
to 10 GB of data. Now, evolution usually happens in populations of
thousands if not millions of individuals. If each individual has a 10 GB
genome and you've got a million individuals, that's 10 petabytes of
data, right there. And if you want to keep a complete record of the
genome of every single organism that has ever lived... we're easily
talking about exabytes of data here.
And then of course, there's the sheer implausibility of /creating/ life
in the first place. You might have to wait a *long* time for your
randomly mixing chemicals to do anything even remotely interesting.
Come to think of it, evolution is very, very slow anyway. To get
anything interesting, you would have to have vast environments of varied
types to inhabit, and you would have to wait a very long time.
In all, simulating life as it exists on Earth is infeasible. All the
computers on Earth couldn't handle a few microbes, never mind anything
that could be called an ecosystem.
Most artificial life simulations don't do this, of course. They simulate
a small data set, apply some kind of arbitrary "fitness" function to it,
and keep all the individuals with fitness above some arbitrary cutoff
value. They then do some kind of duplication / mutation process, and repeat.
The thing is, usually the way the fitness function is set up, there is
exactly one possible solution, and the system is so simple that there's
only a handful of ways to achieve that solution. And the whole machinery
of the system is very simple. Usually only one tiny component of it can
change.
In real living systems, on the other hand, *everything* can potentially
be modified. For example, an organism can evolve a brand new amino acid.
Not just theoretically; this has actually happened. But a computer
program that just copies a set of codes according to hard-coded rules
can't ever do something like that.
Real systems have other interesting properties. Organisms can actually
alter their environment. (E.g., Earth's atmosphere didn't originally
contain oxygen. Plants invented that.) And organisms don't just die if
their fitness is less than X, otherwise live forever. They live or die
depending on how favourable the conditions are. There are predators and
prey. There is competition for space, food and materials. All this
richness that the computer simulations almost never include.
On the other hand, I'm still at a loss for how to include all this
interesting stuff without the simulation slowing down to the point where
it's slower than *actual* evolution...
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Invisible wrote:
> One problem is chemistry.
If you haven't, you really really ought to read Permutation City by Greg Egan.
--
Darren New, San Diego CA, USA (PST)
Serving Suggestion:
"Don't serve this any more. It's awful."
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"Invisible" <voi### [at] dev null> wrote in message
news:4d3dac89$1@news.povray.org...
>
> On the other hand, I'm still at a loss for how to include all this
> interesting stuff without the simulation slowing down to the point where
> it's slower than *actual* evolution...
I remember my high school chemistry teacher once taking the time to mention
"how improbable we are". When you consider everything from getting ANY type
of life started in the first place, right up until the point where sentient
life develops, it really makes you think. I've even heard it said that
without the moon, there is no chance that humans would have developed, since
it has often protected us from asteroid impact. Every time organisms
started evolving to a certain level, BANG!
Anyway, yes. There are so many things to consider that it really makes you
wonder if we actually are alone in the universe. Perhaps the odds of life
evolving to this point are 1x10^21 to 1. I'd like to think that's not the
case, but it does make me wonder. At that point, it becomes more of a
philosophical issue, rather than a scientific one. At this point, we have
"one in a row" to work with, which really doesn't help very much.
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UncleHoot wrote:
> I've even heard it said that
> without the moon, there is no chance that humans would have developed, since
> it has often protected us from asteroid impact.
Actually, I have heard it was the moon skimming off excess atmosphere.
Otherwise, the earth would be like Venus.
--
Darren New, San Diego CA, USA (PST)
"How did he die?" "He got shot in the hand."
"That was fatal?"
"He was holding a live grenade at the time."
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UncleHoot <jer### [at] questsoftwarecom> wrote:
> I remember my high school chemistry teacher once taking the time to mention
> "how improbable we are". When you consider everything from getting ANY type
> of life started in the first place, right up until the point where sentient
> life develops, it really makes you think. I've even heard it said that
> without the moon, there is no chance that humans would have developed, since
> it has often protected us from asteroid impact. Every time organisms
> started evolving to a certain level, BANG!
It has also been hypothesized that without Jupiter there would probably
be no life on Earth because Jupiter has cleared the solar system from most
of the dangerous asteroids. OTOH, another study contradicts this and claims
it has no effect (and may, in fact, be the opposite, that Jupiter might
actually cause us *more* danger than less, but we have just been lucky
so far).
Even if the Moon has helped the formation of life in some way, it doesn't
mean that life would be impossible without it. Even if the danger of
total destruction is greater, life can still get lucky. If not on this
planet, on one of the trillions and trillions of other planets out there
(this is the anthropic principle).
> Anyway, yes. There are so many things to consider that it really makes you
> wonder if we actually are alone in the universe.
My take: If there is life in the Universe (which happens to be the case),
some of that life must have been the first one to form. Well, we might just
be that first, don't you think?
The anthropic principle can also be applied in this case: The first
intelligent life to form will inevitably wonder why they don't detect
any other intelligent life. The answer is pretty obvious: Because they
are the first, and there is no other intelligent life yet.
--
- Warp
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Warp wrote:
> My take: If there is life in the Universe (which happens to be the case),
> some of that life must have been the first one to form. Well, we might just
> be that first, don't you think?
I always enjoyed thinking about such things. What if we really *are* in the
middle of the universe, and it's not that space is expanding, but only that
everything really is rushing away from us because it all started right near
here? :-)
--
Darren New, San Diego CA, USA (PST)
"How did he die?" "He got shot in the hand."
"That was fatal?"
"He was holding a live grenade at the time."
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Le 25/01/2011 21:11, Warp nous fit lire :
> The anthropic principle can also be applied in this case: The first
> intelligent life to form will inevitably wonder why they don't detect
> any other intelligent life. The answer is pretty obvious: Because they
> are the first, and there is no other intelligent life yet.
>
There is no intelligent life yet.
http://xkcd.com/638/
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On 25/01/2011 08:11 PM, Warp wrote:
> My take: If there is life in the Universe (which happens to be the case),
> some of that life must have been the first one to form. Well, we might just
> be that first, don't you think?
My understanding of general relativity is limited, but I was under the
impression that "first" is not a meaningful concept at relativistic
velocities.
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Darren New <dne### [at] sanrrcom> wrote:
> I always enjoyed thinking about such things. What if we really *are* in the
> middle of the universe, and it's not that space is expanding, but only that
> everything really is rushing away from us because it all started right near
> here? :-)
What's the difference?
--
- Warp
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On 1/25/2011 2:06 PM, Warp wrote:
> Darren New<dne### [at] sanrrcom> wrote:
>> I always enjoyed thinking about such things. What if we really *are* in the
>> middle of the universe, and it's not that space is expanding, but only that
>> everything really is rushing away from us because it all started right near
>> here? :-)
>
> What's the difference?
>
In terms of the universe in general, none. The "edges" are one big blur
of stuff moving away too fast to see anything but the blur from it, and
without reference to the edges, you can't define the "center". In
relation to everything else... umm.. just pick something to be the
center, and go with it?
--
void main () {
If Schrödingers_cat is alive or version > 98 {
if version = "Vista" {
call slow_by_half();
call DRM_everything();
}
call functional_code();
}
else
call crash_windows();
}
<A HREF='http://www.daz3d.com/index.php?refid=16130551'>Get 3D Models,
3D Content, and 3D Software at DAZ3D!</A>
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Orchid XP v8 <voi### [at] devnull> wrote:
> On 25/01/2011 08:11 PM, Warp wrote:
> > My take: If there is life in the Universe (which happens to be the case),
> > some of that life must have been the first one to form. Well, we might just
> > be that first, don't you think?
> My understanding of general relativity is limited, but I was under the
> impression that "first" is not a meaningful concept at relativistic
> velocities.
That would be paradoxical.
Assume that intelligent life evolves in planet A, and it starts sending
radio signals to outer space. These radio signals eventually reach planet B.
Some time later life evolves in planet B to a point where they can receive
these signals from A. Clearly, intelligent life evolved in A first, and in
B after that.
If there was an external frame of reference where the intelligent life
forms in B before it forms in A, from this frame of reference it would look
like B is receiving radio signals from A before any intelligent life in A
has evolved (and started sending those signals). In other words, from this
frame of reference it would look like B is receiving radio signals from the
future. This would be paradoxical.
(Obviously if the external observer can see the radio signals arriving
at B, and hence see that B has evolved to the point of being able to receive
and interpret those signals, this external observer can trace the source of
those signals to A and see what is sending them.)
--
- Warp
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Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> I always enjoyed thinking about such things. What if we really *are* in the
>> middle of the universe, and it's not that space is expanding, but only that
>> everything really is rushing away from us because it all started right near
>> here? :-)
>
> What's the difference?
Well, if it was my way, we'd be special. Or at least in a special place.
If you assume we aren't in the middle, then the only reasonable conclusion
is that space itself is expanding, i.e. that everything is the middle. If
we're actually in the middle, it's possible space is completely static, and
everything is just moving away from the center, without any additional space
being created between galaxies. It kind of changes the whole viewpoint of
the Big Bang. (Yes, I know it's nonsense, but think of it in a sci-fi novel
kind of way.) All of space already existed, then there was this big
explosion right about where we are, and everything is still rushing away
from that.
Or perhaps space isn't expanding, but since we're in the center, time is
slowing down as you move farther away. The galaxies aren't red-shifted
because they're receding, but because their time is actually running slower
the farther you get from the center. Which, again, supports us as being the
first species to have evolved to sapience, since we happen to be in the area
of the universe where time is running fastest.
--
Darren New, San Diego CA, USA (PST)
"How did he die?" "He got shot in the hand."
"That was fatal?"
"He was holding a live grenade at the time."
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Warp wrote:
> Orchid XP v8 <voi### [at] devnull> wrote:
>> On 25/01/2011 08:11 PM, Warp wrote:
>
>>> My take: If there is life in the Universe (which happens to be the case),
>>> some of that life must have been the first one to form. Well, we might just
>>> be that first, don't you think?
>
>> My understanding of general relativity is limited, but I was under the
>> impression that "first" is not a meaningful concept at relativistic
>> velocities.
>
> That would be paradoxical.
>
> Assume that intelligent life evolves in planet A, and it starts sending
> radio signals to outer space. These radio signals eventually reach planet B.
>
> Some time later life evolves in planet B to a point where they can receive
> these signals from A. Clearly, intelligent life evolved in A first, and in
> B after that.
If A and B are separated by space-like distances, neither is first. Here
you're postulating that A and B (where A and B are the evolution of initial
radio-emitting life) are separatd by time-like distance.
As you say, if one is in the past light-cone of the other, there's a first
and a second. It only gets ambiguous where neither of the two 4D events are
in the direct past light-cone of the other.
--
Darren New, San Diego CA, USA (PST)
"How did he die?" "He got shot in the hand."
"That was fatal?"
"He was holding a live grenade at the time."
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Darren New <dne### [at] sanrrcom> wrote:
> Or perhaps space isn't expanding, but since we're in the center, time is
> slowing down as you move farther away. The galaxies aren't red-shifted
> because they're receding, but because their time is actually running slower
> the farther you get from the center. Which, again, supports us as being the
> first species to have evolved to sapience, since we happen to be in the area
> of the universe where time is running fastest.
Sounds reminiscent of Vernor Vinge... :)
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>> My understanding of general relativity is limited, but I was under the
>> impression that "first" is not a meaningful concept at relativistic
>> velocities.
>
> That would be paradoxical.
Yes. It's general relativity. It bemuses everybody.
> Assume that intelligent life evolves in planet A, and it starts sending
> radio signals to outer space. These radio signals eventually reach planet B.
>
> Some time later life
Your language is still assuming that "earlier" and "later" are valid terms.
A small thought experiment: There are two parallel train tracks and a
train station in the middle of the tracks. There is a train sitting at
one end of one line, and another train at the opposite end of the other
line. The station and both trains synchronise their clocks, and at
exactly noon the two trains accelerate down the track to relativistic
speeds. Each train emits a flash of light at 1PM, according to the
on-board clock.
Applying the Lorentz transform makes my head spin. But the general
result is this:
- Train A emits a flash at 1PM. Since train B is travelling at
relativistic speed with respect to train A, from train A the clock on
train B appears to have slowed down, and so it appears that flash A
happens /before/ flash B.
- Train B emits a flash at 1PM, and by the same argument it appears that
flash B occurs /before/ flash A.
- Standing on the station platform, both trains' clocks appear to have
slowed down by the same factor, and hence both flashes appear to happen
at /the same time/.
Thus, depending on who you ask, flash A occurs either before, after, or
at the same time as flash B. QED.
Now replace speeding trains with moving planets, add in the influence of
gravity and perhaps the negative curvature of space, and call me back
when you get over the searing pain in your brain...
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Darren New <dne### [at] sanrrcom> wrote:
> If you assume we aren't in the middle, then the only reasonable conclusion
> is that space itself is expanding, i.e. that everything is the middle. If
> we're actually in the middle, it's possible space is completely static, and
> everything is just moving away from the center, without any additional space
> being created between galaxies.
In that situation, why would someone in a galaxy not in the center of the
universe not see all the other galaxies receding?
(Anyways, I think that the reason why the universe must be expanding
rather than all galaxies receding from us simply because they got an
initial velocity away from the center is that in the latter case all the
galaxies would be receding from us at the same speed regardless of
distance, while in an expanding universe the farther away from us the
galaxy is, the faster its recession speed, which is what is observed.)
--
- Warp
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Invisible <voi### [at] devnull> wrote:
> >> My understanding of general relativity is limited, but I was under the
> >> impression that "first" is not a meaningful concept at relativistic
> >> velocities.
> >
> > That would be paradoxical.
> Yes. It's general relativity. It bemuses everybody.
General relativity does not introduce paradoxes.
> > Assume that intelligent life evolves in planet A, and it starts sending
> > radio signals to outer space. These radio signals eventually reach planet B.
> >
> > Some time later life
> Your language is still assuming that "earlier" and "later" are valid terms.
Clearly if B receives a radio signal from A, the radio signal was sent
before it was received. The signal being received before it had been sent
would be paradoxical (it would mean that the signal travels back in time,
which would require FTL travel, and as we know, radio signals don't).
If we define the concept of "intelligent life" at "capable of sending
and receiving radio signals to/from space", clearly intelligent life
developed in A before it developed in B.
I'm not saying there aren't situations where whether A evolves before B
or the other way around depends on the frame of reference. What I am saying
is that when A's light cone (which started when intelligent life appeared
on A) reaches B (before intelligent life appears on B), it becomes
unambiguous. An ambiguous situation in this case would require FTL (and
hence time) travel.
Hence you can unambiguously state that intelligent life developed in A
before it developed in B.
--
- Warp
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Bill Pragnell wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> Or perhaps space isn't expanding, but since we're in the center, time is
>> slowing down as you move farther away. The galaxies aren't red-shifted
>> because they're receding, but because their time is actually running slower
>> the farther you get from the center. Which, again, supports us as being the
>> first species to have evolved to sapience, since we happen to be in the area
>> of the universe where time is running fastest.
>
> Sounds reminiscent of Vernor Vinge... :)
While he is one of my heros, that idea is my own. :-)
--
Darren New, San Diego CA, USA (PST)
"How did he die?" "He got shot in the hand."
"That was fatal?"
"He was holding a live grenade at the time."
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Warp wrote:
> Darren New <dne### [at] sanrrcom> wrote:
>> If you assume we aren't in the middle, then the only reasonable conclusion
>> is that space itself is expanding, i.e. that everything is the middle. If
>> we're actually in the middle, it's possible space is completely static, and
>> everything is just moving away from the center, without any additional space
>> being created between galaxies.
>
> In that situation, why would someone in a galaxy not in the center of the
> universe not see all the other galaxies receding?
They would, but it would be asymetrical. The galaxies between them and us
would be receding from them more slowly than the galaxies on the other side
of them from us.
> (Anyways, I think that the reason why the universe must be expanding
> rather than all galaxies receding from us simply because they got an
> initial velocity away from the center is that in the latter case all the
> galaxies would be receding from us at the same speed regardless of
> distance, while in an expanding universe the farther away from us the
> galaxy is, the faster its recession speed, which is what is observed.)
Unless the galaxies all exploded out at different speeds, so of course the
ones farther away are receding at higher speeds. ;-)
--
Darren New, San Diego CA, USA (PST)
"How did he die?" "He got shot in the hand."
"That was fatal?"
"He was holding a live grenade at the time."
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Darren New <dne### [at] sanrrcom> wrote:
> > (Anyways, I think that the reason why the universe must be expanding
> > rather than all galaxies receding from us simply because they got an
> > initial velocity away from the center is that in the latter case all the
> > galaxies would be receding from us at the same speed regardless of
> > distance, while in an expanding universe the farther away from us the
> > galaxy is, the faster its recession speed, which is what is observed.)
> Unless the galaxies all exploded out at different speeds, so of course the
> ones farther away are receding at higher speeds. ;-)
However, in an expanding universe the recession speed accelerates
(because the more the galaxy recedes, the larger the distance from us,
and hence the larger the recession speed). In a situation where the
galaxies simply got an initial speed the recession would be constant.
(Well, in fact that's not true: The recession speed would actually be
decelerating because they are slowed down by the gravity of all the other
galaxies.)
It then comes down to whether we can measure whether the recession speed
of a galaxy is accelerating or not. (Can we?)
--
- Warp
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Warp wrote:
> It then comes down to whether we can measure whether the recession speed
> of a galaxy is accelerating or not. (Can we?)
You would hve to look for changes in the redshift. I wouldn't think they're
changing recession speed enough for that to be detectable with current
instruments. Especially (I think) if recession speed is increasing because
of increased space between us and not actual acceleration of the galaxies
(because acceleration of the galaxies would affect the photons at the source
while increasing space would only accumulate over time).
--
Darren New, San Diego CA, USA (PST)
"How did he die?" "He got shot in the hand."
"That was fatal?"
"He was holding a live grenade at the time."
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