> The answer was no: in more 1000 trials with randomly assigned planet sizes put through a virtual Kepler’s detection scheme, a pattern of similarly-sized planets in the same systems never emerged. This computational experiment did not reproduce what we observe in the Kepler planetary systems. Thus, the regular sizes of planets is a real astrophysical pattern.
This is actually a really cool use of computer simulations that I haven't noticed before (but I'm sure has been done in the past): simulating expected output for a known bias.
I wonder if it would be feasible to do the reverse too for a kind of parameter fitting to fix our model:
1. Create a reasonable approximate model for both Kepler's expected detection bias and for planet size distribution.
2. Constrain parameter space for these models as much as possible, to minimize the search space.
3. Using these models, generate a set different planetary sets for different parameters.
4. Find the outputs with the closest match in statistical "shape" of the actually measured data.
5. generate new input parameters based on these output that lead to set outputs to refine shape until certain level of matching has been found
If done naively this would probably take a lot of computation and result in large a solution space: the more parameters, the higher the conditionality of this space. So the models should be approximations with as few parameters to produce reasonable results, and with constraints on said parameter values based on known physics. This would narrow down both the parameter space to search the possibly valid outputs of this space.
Based on these parameters differ from the output we had expected before, we might then get a direction of where to look for the physics that does explain the distribution.
Kepler glares at single piece of our galaxy and monitors about 150,000 stars simultaneously.
Kepler is nice for finding large planets that orbit their stars in days.
If you wanted to find planets like Pluto using the transit method, you'd have to look at its star for about 750 years (generally one wants to observe at least 3 transits) - albeit Pluto being even smaller than our own Moon, I'd guess it could not be detected.
We're learning something here but we don't really have enough information to know how remarkable our solar system is.
But at what distance from the host star can it detect planets of this size?
* The formation of any life at all
* The jump from single-celled life to multi-cellular organisms
* The ability to create/use/pass on knowledge of tools
This aggregate of 'filters' is what's important.
We and we alone have the one and only Trump ;-)
This strikes me as wrong. If you want to know if your filter is bad, you plug in ground truth and add known noise models. If you want to know if your noise models are wrong, you cant do the same thing, you need to point your sensor at a known object (e.g. calibrate).
They seemed to have done a cursory analysis of the former type, which is not the same as saying "our pea-pod hyoothesis is correct".
The method has some known biases that they were ensuring wouldn't explain the given pattern in the data. Depending on the depth of the simulation, it may have also been able to account for some unknown biases in the method.
Now even under your interpretation, I'm curious about which known object you'd suggest they use.
Think on this, the one solar system we can empirically confirm with multiple observation techniques, i.e. we've sent satellites to other planets in, is way different than solar systems we are observing by measuring light differences from light years away.
Basically a huge of range of things have to work on large timescales for intelligent life to evolve on a planet.
Which is why intelligent life apart from us could just be absent or very very rare and far away.
Because our solar system didn't end up with the "peas in a pod" pattern, planet formation they also posited a period of violent collisions that stirred things up.
Wild, uneducated, and necessarily oversimplifying speculation: perhaps all these early collisions brought water which helped encourage development of life, and led to the formation of Jupiter, which then protected that life's development.
Basically things have to (not) happen in a series of steps for life to form, even if other things like a rocky planet being situated in the goldilock zone come true. This is apart from a lot of other factors, like not having a big sun etc etc.
All this suggests even if we consider 'Terrestrial mediocrity' to be true. Life could just very very rare across the universe, if not totally absent.
If we see that in all star systems we know that evolved intelligent life (even if there's only 1 we know of) there is a large Jupiter-like planet, and that's very atypical among star systems, that suggests that Jupiter might have increased the probability that intelligent life evolved here.
Again, we've only ever observed a single solar system up close.
There's plenty of differences from our own solar system out there that also don't fit that pattern. Gas Dwarfs are a planetary type that we don't have in our own solar system, for example:
Its kind of mind blowing, we have techniques both theoretical and practical to only see pixels and yet come up with their exact dimensions.
Even a star wouldn't be anything more than a fat pixel, and the planet would be more like a thin pixel. Plus the star dimming, given the orbit would also be a long drawn phenomenon, like in case of earth(1 year).
I understand we ideally decide these things based on color of the light we see. And light waves stretch as the distance increases, and it can all be figured out by doppler effect.
But its still kind of mind blowing how much we can infer from just these things.
Any explanation to this? I'd assume small planets are just harder to detect. Large planets could be gas giants that react differently to our observation technique. Also they tend to form further away from the star, leading to a longer orbital period and fewer observations. Could these contribute to an observation bias and does the simulation include these factors?
Yes, that's what the "put through a virtual Kepler’s detection scheme" part refers to. So she:
1. Generated a bunch of random planet sizes.
2. Simulated what the detector would have reported for each.
3. Compared those virtual detections against the real detection data.
If the two results had matched, it would imply real solar systems have random planet sizes and the bias they see is from the detector. Since the two results are different, it implies the actual solar systems are not randomly sized with the apparent uniformity coming from detector bias.
(There could, of course, be a third factor where planets are randomly sized but the measured bias comes from something else.)
I think this would be really hard. For example, you need to simulate how the detector responds to different planet compositions, different signal to noise ratios at different distances from the star. A sphere in vacuum model may be a gross simplification.
Since it only measures how much light decreases, I assumed it's only measuring planet size, and that we're totally ignorant about planet mass and density?
In other words, it could just be that planets in similar orbits have similar sizes, which would be roughly consistent with our own Solar System.
Jupiter alone takes almost 12 Earth years to get around the Sun. It seems to me that an observer on a remote planet on the same plane as our own Solar System, observing us, would likely only see the inner 4 planets (if anything at all) during a 4 year observation window similar to Kepler.
I wish researchers weren't biased to produce papers, it doesn't help us with honestly understanding our universe.
The Nice model provides a potential explanation for our setup, which essentially requires Jupiter to have formed far out, moved inwards under drag, bombardment, and transfer of angular momentum to planetesimals, and then moved outwards to resonate with Saturn after it formed.
There’s also the Grand Tack model which sees Jupiter careening from 3.5 to 1.5 to 5.2 AU.
As an added bonus, Grand Tack also explains tiny mercury and smallish Mars.
There’s also the question of age - how old are these systems relative to ours? Are we seeing them earlier, or later in their evolution? We don’t have good enough models to yet know.
We need more data, and we also need to understand Uranus and Neptune, which are currently a bit of a question mark.
Sorry, I guess that wasn't as comforting in print as it was in my head.
Or is it just as terrifying to be First?
All of us living now will be long dead before our species die out, so what difference does it really make?
"I once heard a wise man say that if anyone
were to know the whole answer, he would cease to exist."
As an aside from this, you also don't know your statement to be true. Our planet has, multiple times, killed just about every single living species on it. We'd probably stand a decent chance of partial survival due to technology and intelligence, but on the other hand we might not. Think of all the [relatively] near miss large asteroids that we detect only long after it would have been much too late to do anything. And that's something we can actually control. An unfortunate gamma ray burst or other form of harmful electromagnetic radiation could be GG earth with little to no warning or even chance to react.
The chance of an extinction level event happening at any given point is very low of course, but they have happened and will continue to happen. It's just like winning a lottery, one that you'd very much prefer not to win.
The Great Filter for our species is capitalism.
Theories for the formation of our moon suggest a Mars-sized Trojan collided with earth before it was earth: https://en.wikipedia.org/wiki/Theia_(planet)
Asteroids occupying these spaces in our solar system are called Trojans: https://en.wikipedia.org/wiki/Trojan_(celestial_body)
But co-orbital objects exist and one of the most interesting ones is the pair of Saturn satellites, Janus and Epimetheus, their orbit describe a horseshoe and there are pretty cool videos on YouTube with their orbits.
There was an observation five or ten years back that originally looked like it might be two planets in the same orbit, but it turned out that one planet was in an orbit with a period exactly twice that of the interior planet.
We know that our solar system is not random -- e.g., we have the "platonic solids" spacing, for our inner planets. So, our solar system is also not described by the disallowed model.
It's great that some subset of random distributions are ruled out for systems that happen to have planets packed close to their star, but that says nothing at all about how we compare to the the overwhelming majority of other systems systematically excluded from the sample.
As with most results that hit the popular press, any actual significance is garbled to the point of meaninglessness.
But a good graphic can be worth a lot if you ignore the headline.
We already knew gas giants ( a major cause of our peculiarity ) are rare. And we knew that most solar systems had uniform sized planets ( within a particular range ) orbiting very close to their suns.
The article doesn't offer anything new that would make us think the solar system is stranger. It just reaffirms everything we knew and why we thought it was strange to begin with.
Edit: Sorry I shared my fictitious fascination. It would probably make a good movie, humans finding pre-historic humans on Titan or Europa.
Life's gone through a lot of changes over the time it's around. 10,000 years ago there were already humans and the Neolithic revolution was well underway and agriculture was just starting.
Multicellular life was one of the big revolutions but eukaryotes and before that photosynthesis seem to have taken a very long time to evolve. Interestingly we don't have a lower bound for how long it took life to arise once the Earth's surface started having liquid water, so maybe very simple life is pretty common.
I think there is a chance of very simple life on some moons of the gas giants, if they turn out to have liquid water. Most likely this would be single cell organisms (which can grow quite large, a few inches even) or basic multicellular life.
I would be shocked if we found life like trilobites, or even simple plants. It would be the biggest discovery of our lifetime.
So - given that they could live in these moons:
if there is life there already, is it related to Earth life? If not, why not?
If there is no life there, but we could seed these moons, how come they are not seeded already? (From meteorite ejecta etc.)
This is actually a major problem for looking for life elsewhere in the solar system. How do we know it isn't just an Earth grown hitchhiker? Instruments sent to other planets have to be thoroughly cleaned.
In theory they could have been seeded as you describe. The problem is, to quote Douglas Arthur, that "space is really, really big". It's also not great for life, even the hardiest Earth animals can only survive for decades, and it could easily be centuries or millenia until they were deposited anywhere.
Additionally the gas giants, due to their mass, act as a big attractor to stray mass. And any biological life adrift is likely to be sucked into one of these, rather than land on an orbiting moon.
https://en.wikipedia.org/wiki/The_Hitchhiker%27s_Guide_to_th... fiction, doesn't back up any point. But hilarious and correct about the size of space.
Aim the spacecraft at a detected planet or moon, and set it to start ejecting spores whenever it nears a massive object. Make the spores break open and release their biological payload when an accelerometer detects an impact spike, starting a timer, which is reset by changes in acceleration.
Most spores will break open in an environment too hostile for the extremophiles, but some will land in conditions that at least partially overlap those found on Earth, and those could reproduce. A cold desert planet could become a lichen-encrusted planet. A wet volcanic planet could become a vent-tubeworm planet.
If we ever have the wherewithal to reach those planets eons later, the extremophiles that evolve there could be sequenced and broadcast around explored space for use in other spore-ships.
Panspermia from meteorite ejecta would be a slow and painfully random process. An engineered--and, more importantly, aimed--spore craft would increase the odds tremendously.
Unless of course both forms of life share the same origin, but that just raises more questions.
I would also say that before you start drawing up crazy ideas about alternate structures that you should check your own body first; we already have a lot of variants on the theme! Blood is a liquid that has a lot of cells in it. There's a lot of other such circulatory fluids that have cells within them, but are not "cellular" in the sense that they contain nothing but cells. White blood cells do interesting things with cell walls, as does the immune system in general. Cells have structure well beyond just little cubes already, like nerve cells, etc.
Personally I find that when one tries to come up with some funny sci-fi idea for an alternate life form, either A: it's physically implausible or B: something, somewhere on Earth is already doing something very like it, and I don't see middle ground very often.
Though yeah, genetic similarity implying exogenesis would also be an equally interesting result. Would that similarity be organic/natural in nature, or might we just be some species' lab experiment? Perhaps they seeded us with their same genetic origins to discover more about their own evolution and development. This is an experiment I'm certain we'll eventually carry out ourselves. So many interesting possibilities.
(1) They will probably share huge swaths of the basic chemistry and machinery: proteins, sugars, starches, fats, and even more surprising things like cell walls and digestive acid and (something like) DNA. The building blocks of life are basic chemistry, and are some combination of "the simplest possible molecule that can do a thing" and "things that arise naturally from inorganic processes".
(2) There will almost certainly be 0% overlap in terrestrial and alien DNA, even assuming aliens use DNA and use the same four amino acids to encode their DNA and even assuming they have identical proteins and cellular structures. This is because the encoding from DNA to proteins is more-or-less arbitrary, and determined by both the exact cellular machinery used to turn DNA into proteins and by our genetic history. Even in our own cellular machinery, different DNA sequences can code for the same protein, so you can encode any individual protein in a bajillion different ways. The only real reason for to different organisms to share any common DNA sequences is because they both derive from a common ancestor. If our DNA and alien DNA overlap in any meaningful way, even with the tiniest of percent, it's basically conclusive proof of exogenesis of some sort.
So basically, it is very likely we'll be able to eat aliens (probably no more or less likely than how likely it is you can eat any particular plant or animal on Earth, to be honest), and almost impossible that we could ever hybridize alien and terrestrial plants and animals.
I think that even if we found alien life that evolved and developed on a planet much like ours, and used the same amino acids, metabolic processes, and cellular structures, the odds are high that contact with them would result in toxic interactions.
A lot of digestion is pretty elementary, and built upon our stomachs' acid bath -- proteins go in and are unwound and broken down. Most foods that cause problems later down the line contain a protein that both (a) is resistant to the stomach acid, and doesn't break down before hitting the intestines and (b) causes a problem when it hits the intestines.
Barring that - or incorporating elemental poisons like arsenic at levels we can't cope with - I'd personally bet that if you charred a random alien critter over a fire and wolfed it down, it's not crazy that your stomach acids would break down anything that survived the fire and would otherwise harm you, and you'd be able to extract a reasonable mix of sugars, fats and proteins from what you'd ate.
It's not impossible that an entire planet would have some proteins common to all of their lifeforms that both (a) didn't break down easily when cooked or digested and (b) were incredibly lethal to terrestrial life, but there's no ab initio reason to think they would or wouldn't, one way or the other.
Sure, the odds of a particular compound found in some alien lifeform having a toxic interaction with our bodies is small, but I consider the odds of one of the hundreds of thousands of different types of compounds in that lifeform having a toxic interaction is on the higher side.
Oh, and to be clear, by toxic interaction I don't necessarily mean a poison, per se. It could also have a carcinogenic effect, or if the compound is common enough in the creature and undigestable through the stomach and intestines it could overload the liver, etc.
As for carcinogenic effects, well, depends on what the timelines and cancer-rates you're talking about look like. We eat lots of things on Earth that are mildly carcinogenic over a lifetime, and the fact they are doesn't really stop us.
Their proteins may be folded in the opposite direction though. That would make things difficult.
I mean, the ago of the Earth is quite a nice chunk out of the timeline since the Universe got started.
2500 years ago stabbing each other with iron weapons was literally cutting edge technology.
In the past 200 years we have invented: production automobile, airplanes, space flight, launched probes into interstellar space, computers, the internet, ... We have discovered relativity, quantum mechanics, galaxies, ...
Assuming we are able to survive, imagine where we'll be in 200k years. Actually you can't. It's just impossible to even begin to try to imagine that. On that scale we'll likely have even begun to experience evolutionary speciation as we settle different regions of space and end up with extended periods of relative isolation.
And now consider that this entire timeline is but 400k years. That's not even a blink in the eye of the cosmos.
But I think it is likely that there would be internal subdivisions in a complex life-form. This is however likening, branches in trees, to cells in an organism, to crystals in a rock.
We know Kepler results are heavily biased for (1) systems edge-on to us (2) with big planets (3) very close to their star.
The only conclusion to draw is that planets that are all clustered close to their star tend to similar sizes. Then only Mercury is unusual. Even there, it's not unique.
Stars with planets distributed more widely, like ours, have been systematically filtered out of the results. We have no idea how common they are. It might be that they are rare, and that would make us unusual. In that case, distribution would be interesting and relative sizes would be unremarkable.
If in fact they are common, there is no reason to expect sizes in those cases to be uniform.
A system that condensed from a cloud with less intrinsic rotation seems more likely to have its planets clustered close. Less intrinsic rotation could also result in more uniformity.
This article was written by an astronomer working with Kepler, and I wonder why you apparently seem to believe that they are so naive that they forget about the bias in their own research tools.
Furthermore, the article explicitly mentions this issue, and provides an explanation for why they believe it does not apply, making me wonder if you read it at all:
> I concocted (on my laptop) imaginary planetary systems in which the sizes of planets orbiting a given star were random. Could some sort of bias in Kepler’s method of finding planets—which favors the detection of large planets close to their stars—contrive to make the planets in each of my imaginary systems appear to fit the pattern? The answer was no: in more 1000 trials with randomly assigned planet sizes put through a virtual Kepler’s detection scheme, a pattern of similarly-sized planets in the same systems never emerged.
Unless you have a reason to dispute this method of verification of course, but then you should share that.
I personally see no problem: the claim is implicitly that since the measured data does not match the predictions of the model, the model is wrong. The model + known bias of Kepler is used in simulation to generate expected statistical output of measured data sets. The generated data does not match the measured data. Hence, either the model of Kepler's bias is wrong, or the model of what planetary systems to expect.
Since we based the planetary system model on our own solar system, if that model is wrong then that makes our own solar system special.
Exactly. I actually did some research on Weiss.
So she studied astronomy at Harvard where she got her BS, then went on to Cambridge for her masters, and then a PhD from Berkeley. Now she works with NASA.
Odd that all these people who clearly didn't even read the article seem to find supposedly obvious bias and flaws in the research of someone who is clearly among the top young researchers/experts in this field.
These two statements are not equivalent; the model may be wrong in its assumption of uncorrelated planet sizes and star type, for example.
I’m sure if you contacted the journal, authors and reviewers about these obvious errors they’d add your name to the list of reviewers and force this so-called scientist to reevaluate their criteria for publishing worthiness.