13-Billion-Year-Old Alien Worlds Discovered 302
astroengine writes "Two exoplanets have been discovered by scientists at the Max-Planck Institute for Astronomy orbiting the star HIP 11952. But according to conventional thinking, these worlds shouldn't exist. You see, HIP 11952 is a 'metal-poor star and planetary formation is hindered around stars with low metallicity (PDF). This isn't the only thing; as metal-poor stars were the first stars to form when the Universe was very young, these two worlds also formed around the same time. They are therefore the most ancient exoplanets discovered to date."
I'm confused (Score:3)
Re:I'm confused (Score:5, Funny)
"Planets form around sun" certainly was news 13 billion years ago, it just took this long to reach Slashdot's front page.
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it should be impossible as previously thinking was that the only way the elements for planetary formation are created is via prior supernovas. these stars shouldnt have had access to the materials needed to create planets. either there were more -very- early supernovae than thought, or these planets are interstellar captures.
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well, the life of a star is inversely proportional to its size... the bigger the star, the faster it blows up. it *is* plausible that during the early days of the universe when things were much more densely packed than they are now, bigger stars could have formed early on.
but I still think they're most likely trapped planets.
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They're gas giants. They could be 100% hydrogen, thus not needing elements from supernovas.
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Re:I'm confused (Score:5, Interesting)
Early supernovae wouldn't help - the star is formed from the same material as the planets would, and the star demonstrably has almost no metals. Early supernovae would just mean that this star didn't exist (in its current chemistry), or that it is even younger than currently estimated, so as to form before the supernovae.
Interstellar captures are very difficult. Generally speaking, you need three gravitationally interacting bodies to allow a capture, as you need one to carry away some energy. Basically this requires the wanderer planet to turn up just when the star is passing close to another one, and even then to get really lucky. (Most often it is the lowest mass object of the three which gains energy, but we need the planet to lose energy.) Another possibility is you could lose that energy through tidal losses, but this requires the wanderer has very small positive energy initially, and passes very close to the star. Either way, the odds of such a capture are very low.
In addition, we have the fact that this star has two planets, which makes the odds against capture polynomially* smaller. Finally, if two planets were captured, we'd expect them to have different orbital planes. Given that they were detected by the 'wobble' method, I'd expect this could be measured, and would be mentioned if it had been so. However I can't promise that there aren't gravitational interactions which would bring the orbital planes into alignment over 13Gyr. Captures would also initially have highly elliptical orbits, which again the wobble method should notice, and again I don't know if 13Gyr is long enough to circularize the orbits by tidal effects or planet-planet interactions.
* This word brought to you by the Committee Against The Misuse Of The Word 'Exponentially'
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Why so? If the probability of capture of one planet is p, of two planets is p^2, of three planets is p^3, and in the general case it is p^n, where n is the number of captured planets. Or, in other words, the odds decrease exponentialy.
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The probability is exponential in n, but for two planets, it is polynomial in p. I'd fixated on the second fact and missed the first. Given the context that we'd just changed n rather than p, I agree that 'exponentially' is more appropriate here.
I shall submit myself to the Committee for disciplinary action.
Re:I'm confused (Score:4, Interesting)
Well said about the capture. It's very interesting to run an N-body gravitational simulation where the initial state is a bunch of things with random masses and velocity vectors. A whole lot of stuff will be ejected as things settle down. Gravitational capture appears to be hard. That's what I learned, to my initial amazement, when I started playing with N-body simulations. I thought the code had bugs. And then I'd input some solar system ephemeris for the planets and a couple other large objects, and voila, it didn't blow up, things were nicely orbiting :)
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verb tense (Score:2)
So do we say that these planets "are" orbiting HIP 11952, or that they "were" orbiting HIP 11952?
Re:verb tense (Score:5, Insightful)
Well, they're only 375 light-years away, so I'd say that if they had managed to exist for 13 000 000 000 years, they likelihood of them disappearing in the last 375 is pretty low. My bet is on "are".
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Re:verb tense (Score:4, Insightful)
Point is that we now know that planets were formed at a very early stage of the universe.
As for the planets being metal poor, it isn't a surprise really, considering the age of the planets.
Let's put aside that for astronomers everything beyond helium is a "metal", we are talking about iron (Fe) and heavier elements.
Suns can only create elements up to iron in a fusion process, everything else is created in a (super) nova, and those were only starting at the beginning of the universe.
The real surprise here is that planets were formed without (or with few) heavy elements.
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They are in our reference frame.
Re:verb tense (Score:4, Interesting)
So do we say that these planets "are" orbiting HIP 11952, or that they "were" orbiting HIP 11952?
Never mind that this star is in our neighborhood, but you make the mistake of thinking of time as a universal (no pun intended) thing. When the light from a distant star hits us, the star does exist, whether the star is billions of light years away or not. It is meaningless to think that the time that the light traveled has passed, because it hasn't. If you were riding the photons from that star, only a moment would have passed for you.
If we were to go backto the faraway star at the speed of light, we would find it 2*distance older.
Yes, it's difficult to wrap one's head around, so we make up the comfortable lie of considering distant stars being older proportionally to the distance light and radio waves travel as seen from a fixed point. But that point doesn't exist. Time is always subjective, as long as the speed of light in vacuum is considered constant.
And if you thought that makes your head hurt, consider that space itself is expanding, so the distance to a far away star is longer than the distance the light has traveled...
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Time may not have passed for the photon, but time certainly has passed for that distant star.
Um, no. Not without a frame of reference that encompasses both the star and the distance the photon has traveled. The star itself has no such frame of reference.
In short, it's meaningless to say that time has passed at the star, because you can't compare time here to time there. We're constricted by the light cone.
See http://en.wikipedia.org/wiki/Relativity_of_simultaneity [wikipedia.org] for more details.
Captured rogue planets? (Score:3, Insightful)
Possibly they are captured rogue planets [wikipedia.org].
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If all you have is one star and one planet, and you simulate them as point masses (no tidal losses and no slowing down in star's outer atmosphere), capture seems impossible. The planets don't exactly have orbital insertion motors attached. I'd like to see a list of possible mechanisms that would make a capture possible in such a scenario. Remember: to have orbital insertion, you need to dissipate energy. Always.
Have we... (Score:2)
Oblig. Foundation reference (Score:2)
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Ah, but the whole Asimov universe was rich in the metal that mattered.
"Dors!"
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No, Star's End was at the opposite end of the Galaxy from Terminus.
It's all a matter of how you define that.
Endless Hide & Seek (Score:3)
I think there are simply too many things for us to be 100% on. That, to me, is exciting--it allows us to never run out of things to learn about. If we're wrong, we get to keep trying to find out why.
New Universe (Score:5, Insightful)
Everyone Missed The Point (Score:2)
Time Enough For Lithium (Score:2)
Y'know, looking at our own gas giants, it seems you don't need a whole lot of heavier elements to create a non-fusioning sphere around a star. Granted, Jupiter, Saturn, et al seem to have a lot of goodies further down the periodic table. But, I'd guess that planetary formation will work with whatever is in the buffet, even if it's just H and He with a salting of impurities.
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Enjoying the science fiction references in this thread more than the discussion stemming from the article.
Death Star (Score:2)
Don't worry, it'll leave once Alderaan gives up...
Sigh (Score:2)
Av shown this page to a non-geeky friend... (Score:3, Interesting)
News like this should really become mainstream. This kind of humbling, nihilistic conceptualisation of our lives and surroundings could, ironically, save mankind from whatever foolish suicide we'r preparing to ourselves.
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... And she was delighted
Wait... You have a female friend, and you're reading Slashdot???
Old planets (Score:2)
There is no conventional thinking, it's (Score:2)
Ancient planets, huh? (Score:2)
If one has a glowing green band I propose we call it Oa.
So we found planets older than dirt. (Score:5, Funny)
This may be a very bad sign- Great Filter? (Score:4, Interesting)
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The technology required for feasible interstellar travel requires extremely concentrated energy.
Such as uranium 238 and a breeder reactor. The wacko problem still exists, but it's not "Davros with a vial" [google.com] level of wacko.
I also think you're doing a bit of anthropomorphizing here. There's no reason to expect that human mental problems would be common to every form of life out there.
I think it more likely that either life is prevalent in the galaxy and we just don't know it yet, or we're among the first.
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Nothing is "ageless".
Re:Astronomers are so funny (Score:5, Funny)
You are welcome.
Re:Astronomers are so funny (Score:5, Funny)
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Stuffed up your nose in order to escape the army?
Re:Astronomers are so funny (Score:4, Funny)
No. Pointless.
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space is an illusion we use to make sense of the pattern
FTFY
By this logic, you also can't measure distances because space could be infinite.
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Personally, I like (as in, I think it would be cool, not I believe the evidence implies it's true) the idea that space is finite, but unbounded. If that were the case (and you could travel faster than light) you could travel in a straight line (correcting for local [and non-local?] curvature of space) and end back up where you started.
Re:Astronomers are so funny (Score:4, Informative)
http://en.wikipedia.org/wiki/Shape_of_the_universe [wikipedia.org] :
The Wilkinson Microwave Anisotropy Probe (WMAP) has confirmed that the universe is flat with only a 0.5% margin of error.[1] Within the Friedmann-Lemaître-Robertson-Walker (FLRW) model, the presently most popular shape of the Universe found to fit observational data according to cosmologists is the infinite flat model,[2] while other FLRW models that fit the data include the Poincaré dodecahedral space[3][4] and the Picard horn.[5]
Re:Astronomers are so funny (Score:5, Informative)
Re:Astronomers are so funny (Score:5, Funny)
time is not an illusion at all, it is the increase in entropy of the structures of the visible universe, it is a non-conserved state function
So, does time run backward in your freezer, and faster than normal around it?
Re:Astronomers are so funny (Score:5, Funny)
no, the refrigerator does work moving heat to the outside in time with some of that energy thereafter unavailable to do work, increasing the overall entropy of the universe even though causing a local decrease of entropy inside
And that folks, is the definition of a refrigerator here on Slashdot! Still wonder why you don't have any gfs? Seriously though, this is why I love /.
Re: Ford Prefect (Score:5, Funny)
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Time is an illusion. Lunchtime, doubly so.
Quitting time, infinitely so.
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time is not an illusion at all, it is the increase in entropy of the structures of the visible universe
"Increase" is over time so your definition of 'time' includes 'time'. As Fynman himself would say "you have cheated very badly". Entropy is said to be the reason why we can only travel forward in time, ie: it defines the "arrow of time" not time itself. Although it could just as easily be worded the other way around, ie: the arrow of time is why entrophy always increases.
Time, space and the fundemental forces are what I like to call "miracles", they are "a given" and (for now) we just have to accept they
Re:Astronomers are so funny (Score:5, Interesting)
Re:Astronomers are so funny (Score:5, Informative)
Re:Astronomers are so funny (Score:5, Funny)
Being stoned doesn't make you more insightful than anyone else. It just makes you stoned.
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Hey! That was on my last birthday card. Stop reading my mail - and get off my lawn, you damn kids!
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Dude, you've had enough acid. Try the coffee.
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Anonymous cowards are an illusion we use to make nonsense out of slashdot.
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Anonymous cowards are an illusion we use to make nonsense out of slashdot.
Slashdot is an illusion we use to make sense out of anonymous cowards.
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Re:Astronomers are so funny (Score:4, Insightful)
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Time has an age, it is approx 13 billion years old.
Time and space were created at the moment of the Big Bang. Time didnt exist before that, so therefore it has an age.
Re:Astronomers are so funny (Score:5, Informative)
13.75 +/- 0.11 billion years
(The same age [wikipedia.org] as the universe)
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How old is time itself?
No older than the universe. In some cases much younger.
Without the geography of space, time doesn't exist.
We like to think of time as a constant linear, but it really isn't - it's a local phenomenon with large variations. We can say it takes billions of years for the light from the farthest distant galaxies to reach us, but if we were to ride that beam of light, it would only take an instant. If we consider the photons particles, they are very young, and yet as old as the universe.
Re:Astronomers are so funny (Score:5, Insightful)
Nothing is "ageless".
How old is time itself?
I don't think that's a well-formed question. It's like asking "how long is distance?".
Can a star really last for 13 billion years ? (Score:3)
I have read TFA on Slashdot and also the TFA on discovery
On both the title of TFA on Slashdot and on TFA at discovery, we are told that the star was formed 13-billion years ago
On TFA at discovery it was also mentioned that the star, HIP 11952, is 375 light years away
If the star is located in a very distant galaxy some 13-billion-light-years away, the star is already 13-billion-year old, or the star may be no more - but we still see the light from that star since the star light took 13-billion-years travell
Re:Can a star really last for 13 billion years ? (Score:4, Informative)
http://en.wikipedia.org/wiki/Red_dwarf#Description_and_characteristics
It's possible to have stars that can fuse material for as long as 10 trillion years. Yes, T-T-T-Trillion.
The articles I looked at regarding this planet though make no mention to what class of star they're orbiting, so YMMV.
Re:Can a star really last for 13 billion years ? (Score:4, Informative)
It's possible to have stars that can fuse material for as long as 10 trillion years. Yes, T-T-T-Trillion.
10-100 short scale (U.S.) trillion, or 10-100 long scale (Euro) billion. A pretty long time, yes, considering that the universe is considered[*] to be less than 14 billion (short scale) / 14 milliard (long scale) / 14 thousand million (UK) years old.
[*]: It's hard to say with any certainty, because once you get really close to the Big Bang, time will have acted very strange from our perceptive, and what might have been a millisecond in one part of the small budding universe might have been a millions of years in another part.
Re:Can a star really last for 13 billion years ? (Score:4, Interesting)
Probably a red dwarf. They can fuse hydrogen for ages ... many billions of years. If I recall correctly the luminosity, and hence the lifetime, of a star is proportional to roughly M^3.5 (M is mass) so small mass stars will glow with much greater reduced luminosity and correspondingly much greater lifetime. Just so long as it is hot and dense enough in the core to keep fusion ticking over. This is pretty cool, wonder where the metals came for the planets to form? Is it a freak that picked up stuff from a nearby supernova during formation or what? Wonder if any life arose in that system, would have had a long time to advance by now. Just thinking.
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And I'm not an astronomer either, just an interested layman.
Re:Can a star really last for 13 billion years ? (Score:5, Informative)
Can a star really last for 13-billion year and not running out of fuel?
Yes. Our own star is about 5 billion years, and probably only halfway through its life cycle.
Just like with dogs, the smaller ones live longer. Red dwarfs are expected to live for thousands of times the current age of the universe, and simply peter out as they exhaust their fuel, burning it slower and slower, but never having the gravity to cause helium fusion.
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It is a false dichotomy. They are assuming a metal poor star can not form in the current Epoch. I would have said that we discovered that metal poor stars can form in the "modern" universe.
Re:Can a star really last for 13 billion years ? (Score:4, Informative)
Lifetime=1/Mass^2.5.
Note that lifetime here is as a ratio of solar lifetime (so a Lifetime of 1=10 billion years) and mass is in solar masses. The paper gives the mass of HIP 11952 as about 0.83 solar masses, so an estimated main sequence lifetime would be 1/0.83^2.5= 15.9 billion years, after which it would become a red giant. Not liking the odds for its planets at that time, especially the one with a 7 day orbital period. So, it probably has a long while left, though there are wide bounds listed for mass and age, so if it is actually older and heavier, it might be living on borrowed time.
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In fifty years everyone will look back and laugh at us for putting an age on an ageless thing.
All you have to do is find something 14 billion or more years old and you can do that right now. And pick up a Nobel Prize in Physics while you're at it.
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Re:Astronomers are so funny (Score:5, Informative)
Actually, it's unknown what it was like before the big bang.
Like the parent said, time itself did not exist until the big bang, therefor, there is no "before" the big bang. There is no such thing as before time, just as there is no such thing as negative mass or negative distance.
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Bah. If I'm behind you, that's negative distance!
Stupid kids.
Re:Astronomers are so funny (Score:4, Interesting)
Not to snark at you, but Sol is estimated to be 4-5 billion years old and it's only 8 light-minutes away.
But you've raised a really good question...
Off to read up on it.
Re:Astronomers are so funny (Score:4, Informative)
http://en.wikipedia.org/wiki/Main_sequence [wikipedia.org]
They can guesstimate the age of a star based on its light characteristics. Our current understanding is that stars tend to follow a set progression through their evolution, and by looking at the current characteristics of a star (mass, heat, spectral composition), they can guess roughly how old it is.
It's all guesswork, mind you, and it doesn't necessarily tell us that the planets themselves are as old as the star. They could be trapped planets from other solar systems that the stars came into contact with over the years, or even trapped proto-stars that never had enough mass to start fusion... current thinking is that the interstellar medium may have a lot of this type of planet.
Re:Astronomers are so funny (Score:5, Informative)
Didn't get one thing: the article says the star is 13 billions yo, but it's 375 ly from our solar system.
I always have thought that distance meant age. Which other technique there is to tell a star's age?
Distance is... well, distance. The number of light years something is away means that we are looking at what happened that many years ago. In this case, what we see happened 375 years ago. It has nothing to do with the age of the object. However, if we see a galaxy 13 billion light years away, we know that the galaxy is 13 billion years old since nothing is that much older, provided it still exists. We don't really know as we would be seeing it as it existed 13 billion years ago. To see how it looks today, we'll have to wait another 13+ billion years and look at it again.
As for judging the age of a star, I'll take a stab at it, although IANAA. If I recall correctly, there are several methods used to judge the age of a star. We know by looking at what the star is composed of which developmental stage it is currently at. We know by its size and energy output how fast it is burning its fuel. So, if we see a large, bright, hydrogen star, we know that it is fairly young since large hydrogen stars don't last long. We can be more accurate by figuring out how fast it burns its fuel and how much it has left (helium to hydrogen ratio). If we see that it is composed mostly of helium, we know that it is in its second stage. We can judge by its size how long it was in its hydrogen stage before it fused it all to helium.
I have not RTFA, but I believe they are judging that this star was one of the first out of gate judging by how much metal it has in its core, meaning that it is very, very old.
Take with salt. Like I said, I'm no astrophysicist.
What I don't understand is how do the scientist know that these were not rogue planets, formed much later and then became trapped by the star's gravity. Just because a star has planets orbiting it, doesn't mean that those planets formed along with the star.
Re:Astronomers are so funny (Score:5, Informative)
It is difficult for a body not already in orbit around a star to be captured by it unless there is a third body or something else (dust cloud, etc.) nearby to take away some of the kinetic/potential energy involved. If there is no third body then by a conservation of energy argument -- the small body falls toward the star, faster as it gets closer then slingshots around and back into interstellar space. Even if there are "third bodies" around it is just as likely they will transfer energy to the interstellar visitor and send it out with more speed than it came in with. Similar thing happens with the solar system comets -- they are technically in orbit around the sun way, way out there but occasionally one gets perturbed and comes in close -- unless it gets further perturbed by a planet it will fly a practically parabolic trajectory and go right back out to the far edges of the solar system.
Re:Iron poor -- yet still able to build starships. (Score:2)
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All they have to do is make one. One really good one.
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not going to make a starship out of water
Why not? I'd welcome them ice-spaceship-travelling overlords. Extra points if it's ice-9.
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not going to make a starship out of water or gases... so to even invade with starships, they have to already have found sources of metal...
Well, if they do make a starship out of gas, the fan suddenly becomes our ultimate weapon.
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Metals in astrophysics referes to everything other than Hydrogen and helium, so they would not have oxygen to make water.
True, but "metal poor" also means compared to the sun, and there are also big variances in the composition compared to the sun. There can be even more oxygen in a star than what our sun has and it would still be considered "metal poor" if it has far less of other common metals. In most cases, what's measured is the Fe:H ratio, and a star can still have an abundance of, say, carbon (like most red stars) or oxygen (like most yellow stars).
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I dunno. I'd vote Keith Richards.
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Here at Slashdot, we take our comments seriously. At the very least, you are expected to keep a couple of dozen brain cells functioning if you intend to post. Proper spelling and grammar are optional, but highly recommended.
Slow down on the bong hits next time.
Re:maybe they dont exist (Score:4, Informative)
They're only 375 light years away.
Re:maybe they dont exist (Score:5, Funny)
They're only 375 light years away.
Maybe the light took the scenic route.
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We are but specs of dust blow around by time.
Profound!
Oh, l guess you meant "specks".
Re:Alien mystery worlds... (Score:4, Informative)
Orbital dynamics and mr. Occam must be at odds today. Play with an N-body simulator and see how it goes. I don't think most people can claim any sort of common sense here unless they've been playing with one. It usually doesn't work the way one would expect. For example, one could naively think that gravity, as an attractive force, will cause eventual collapse if you start simulation with a random bunch of bodies having 0 relative velocity. To one's surprise, then, not only there will be no collapse, but a bunch of objects will get permanently ejected from such a system. Getting things cleanly orbiting one another in low-eccentricity orbits can be considered a lucky occurrence as well. That's what I remember from when I was in high school -- that's the first and last time I felt like coding up N-body (it's a pain -- naive algorithms don't work if you've not got a couple centuries to wait for the results), so feel free to correct me if I'm wrong.