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Do 'Ultracool' Brown Dwarfs Surround Us?
astroengine writes "The recent discovery of two very cool 'T-class' brown dwarfs in our cosmic neighborhood has prompted speculation that there may be many more ultracool 'failed stars' nearby (abstract). Not only are these objects themselves very interesting to study, should there be many such brown dwarfs spanning interstellar space. Perhaps they could be used as 'stepping stones' to the stars."
Especially if they manage to show a link between this research, the fairly regular extinction events over the history of the planet, and The Nemesis Hypothetical Star...
Do not look into laser with remaining eye.
Yeah, sure. Because when you're on a 100 year cruise to colonize Sirius the thing you really want to do
with your intertia is slow down and stop at your local brown dwarf to pick up a pack of Coke and some cigs.
I can't believe how racist slashdot has become. They may be ultra cool, but calling them brown is inciting hate. African American little people is the PC term.
In order to have elements beyond carbon one needs a bigger star than our yellow sun. Large stars tend to supernova and become brown dwarfs or black holes in some cases. Some stars fail and become brown dwarfs as well. But you can still get hydrogen from them from solar winds for spacecraft.
It is hard to detect them because the brown dwarfs are Earth size and do not give off much heat or light. Our sun Sol is supposed to have a companion star nearby called Nemesis that is a brown dwarf and throws asteroids at our solar system.
Read this real quick and thought it was an advance report from Comicon...
Ultra-cool brown dwarf? How about p-diddy?
blah blah blah
Tut! Oh God! Why didn't we think of this! It's so obvious! That's where all our research money has gone to waste, assuming that we are omnipotent in our calculations and not including error ranges!
Hell, let's just assume that that 83% (or thereabouts) of all matter in the universe being "missing" is just us overlooking that there might be planets on every star (and the fact that the biggest planet in our own Solar System weighs less than 0.1% that of the Sun).
God, it's so obvious. Why did we never take this into account in any of our billion-dollar-funded research programs filled with (quite literally) rocket-scientists?
Or maybe we did, you pillock...
There will never be any interstellar trade. The distances and velocities involved require energy expenditures vastly higher than the cost of any valuables you may wish to transport. You might say the costs will be "astronomical". The only movement between stars will be radio signals and initial colony ships.
P.S. we infer most of the mass of the universe through the movement of things we can observe (because all mass bends space-time) - and we get a pretty god-damn accurate picture of what MUST be in it's local neighbourhood for it to act like it does. The fact we can't see the mass itself is neither here nor there - we're literally looking at how a galaxy (BILLIONS OF STARS!) behaves and inferring how much it and it's surroundings must weigh in order to act like that. There's about 170 billion galaxies to look at.
On those scales, extra planets and a few missing stars don't even factor into the error ranges because they are so inconsequential. Hell a couple of extra galaxies doesn't even register.
As regular brown dwarfs would have you know, "ultracool" brown dwarfs are actually hipster poseurs.
your thin skin doesn't make me a troll
The idea of Y-class brown dwarf stars are neat and all, but this whole 'stepping stone' idea is not really explained. Why would we use these as stepping stones? Is there an advantage to it? I don't understand why we would use them is all.
I call it 'The Aristocrats'
Yet another place the JWST (James Webb Space Telescope) would be fantastically useful!
Also, how seriously would the presence of previously undetectable ultra-cool stars affect the search for dark matter? Aren't we looking for energy/matter based off some energy level, and might that mass be tucked away in the form of ultra-cool stars, just to cool to detect?
No. As much as it seems fashionable to bash (non-baryonic) dark matter here on Slashdot, our current astrophysical theories put constraints on how much baryonic dark matter (MACHOs) is possible. Our current theories on Big Bang nucleosynthesis place bounds on how much baryonic matter can remain dark. If there really were enough baryonic matter to account for all the dark matter that should be there based on indirect observations, then the abundances of various isotopes produced by Big Bang nucleosynthesis would be quite different from what we observe. That could also mean that our current theory of the Big Bang is completely wrong, but that seems unlikely to say the least. These theoretical considerations imply that even if more MACHOs are found, non-baryonic WIMPs will still have to make up a large fraction of dark matter.
Qu'on me donne six lignes écrites de la main du plus honnête homme, j'y trouverai de quoi le faire pendre.
Information may be what is traded. But self-replicating mining and factory machines can bring ship building and fuel mining costs to essentially zero. Then the only cost is time of assembly and time of transit. Maybe there is something physical that would be worth it.
The number of extra planets or dark stars you would need to matter, *would* show up because there would need to be soo many. They have been looked for you know. For example if there are millions more of these cold brown dwarfs than what we already have estimated, then the average distance to them would be so small that we would be able to observe many of them (probably would imply at least a few within the ort cloud). We would see many more micro-lensing events ... etc etc.
You can't have your cake and eat it too. If there is enough to explain dark matter, there is more than enough that observing them would be quite trivial.
On top of all that, such objects do not explain other observations of dark matter. In particular, the bullet cluster. We can in fact "see" dark matter.
If information wants to be free, why does my internet connection cost so much?
Evidence: The bullet cluster. The observations imply that there is a huge amount of mass that was moving with each galaxy before the collision, that is not baryonic. That is interacts only via the force of gravity and is not affected (or at least very very weakly interacting) via the other forces, most importantly the electromagnetic force.
There is quite a few other effects that dark matter can explain nicely. We are in fact devising experiments to attempt to observe dark matter particle candidates.
If information wants to be free, why does my internet connection cost so much?
So (like another poster) I'm not sure how useful these would be as refueling dumps (stepping stones). I mean, once you've gotten a starship up to speed then slowing it down to refuel just to speed up again just doesn't make sense. I guess the only use would be if there were consumables that could be obtained for "generation ships" or if some large piece of the ship needed repair material (as in the ice shield on the starship in Arthur C. Clarke's "The Songs of Distant Earth"). I guess they might make sense if they were power stations that could beam (lasers?) energy to a passing ship.
Another (briefly discussed) issue is that of missing matter. I realize that the amount of planetary matter must be a negligible contribution but why couldn't there be 100s or 1000s of brown dwarfs for every sunlike star? Is it because we'd see a lot more microlensing events or our Oort cloud would be perturbed much more frequently? It would be kinda cool if there were much more of these things out there rather than stuff we can't interact with.
Are there any "habitable zones" around them? Sure there wouldn't be any light but it'd be like being next to a nice campfire for some really close orbits. Would the orbits be too close and decay in a geologically insignificant amount of time?
If we ever got fusion drives (but nothing better) maybe having lots of these things would allow galactic expansion as a long slow crawl at very small fractions of the speed of light. In which case setting up colonies of couple thousand AUs over many millennia could gradually establish a dark web between the brightly lit stars (so much for Star Trek). These bodies then wouldn't be waypoints. They would be our homes.
Not good. How did the last 50 years go? Oh I get it! By "Progress" you mean "Neglect" and by "Pointless" you mean "Imossible".
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So these brown dwarfs are essentially big balls of (mostly) hydrogen with the centers under tremendous pressures and temperatures but not quite hot enough to "light" (in a fusion sense). Well what would happen if you managed to drop a fusion bomb on it? (On or near the surface where the temperatures are low but the high gravity might still compress the hydrogen into the megabar range).
While (probably) it would just fizzle, could the concentrated energy ignite just enough so the whole star went boom? (Like a Type I supernova?). I mean the "temperature" of an H-Bomb is in the hundreds of millions of degrees maybe it just requires one tiny (if an H-Bomb is "tiny") spark. Just like you can pour millions of gallons of gasoline on a barely sub-critical mass of Uranium and it won't go bang but one small neutron generator and you've got a mushroom cloud. While the impacts of asteroid and larger bodies could deliver a lot more energy, an H-Bomb could do so more INTENSELY.
I guess this is what the first H-Bomb scientists were worried about when they feared the first H-Bomb *might* ignite the water vapor in the atmosphere and consume the entire world. Just how easy would it be to blow one of these things up? Could you do it with even smaller cooler less dense bodies, say Jupiter (as proposed by sci-fi writer Charles Sheffield) or Neptune? (Tried it on earth, nope doesn't work). Lastly, our sun is already alite, but the RATE of fusion reaction is very slow (each gram of the sun produces far less energy per time than, say, a live elephant). Could we speed it up? Could an H-Bomb (or a suitably powerful laser such as was used in one of the Man-Kzinti war sci-fi books) trigger a local (or maybe not so local) explosion?
I guess this was the general idea behind the movie "Sunshine" (good movie). Seems they had some sort of very dense (causing a local gravitational field) fission bomb to re-ignite the sun. Wish they had a companion book to flesh out some of the details.
Anyway I know these ideas are probably non-sensical to any physicist but don't have enough math and physics knowledge to calculate it for myself. If anyone of you is so inclined and it won't take much time or effort, I'd appreciate the debunking (or not!) of this idle speculation.
(For even crazier speculation, how about igniting all that supposedly great fusion fuel Helium-3 that is just lying around on the lunar surface? Would it be enough to blow the moon out of orbit a la "Space 1999"?)
I have presented to several of my friends/coworkers/family the idea that interstellar space IS NOT the great void we seem to have been assuming for so long, but instead may well be filled with all manor of significant objects, including brown dwarfs, rogue planets, etc. We don't have to make some multi-lightyear jump across nothingness to reach the stars; we can jump from world to world to world, like a great migration wave-front, gathering resources and establishing waypoints as we go. It was an article in Analog SF magazine that got me thinking along these lines. It may take generations to reach the next major star, but at least there will be fun exploration along the way.
VASIMR to Mars!
Everything is relative. It shouldn't be too difficult to find a brown dwarf heading somewhat in the correct direction. You'd have to spend some fuel to match the trajectory, but with judicious selection you could minimize that.
Weaselmancer
rediculous.
Well, not really. If you're invoking Occam's razor, GR itself violates it horribly compared to Newtonian gravity... unless you look at it a particular way. I mean, who the hell wants to change
* F=m_i a /r^2
* F=G M m_g
into
* G_\mu\nu=\kappa T_\mu\nu
where \mu and \nu each run from 0 to 4? High-school maths into university level maths? It's only if you look at it from the level of an action that it looks so simple...
Personally I feel adding in extra matter fields that are unmotivated other than SUSY (which is itself a horrific violation of Occam's principle unless you look at it the right way - the "right way" being some symmetry arguments based ultimately on group theory) and are barely motivated there is less palatable than accepting that Einsteinian gravity is potentially flawed, and our application of Einsteinian gravity *certainly* is. (It is. The open questions are just how inaccurate our calculations are. Most likely, the errors are insignificant, but this has to be checked before we run around adding a million scalar fields - none of which have been observed in nature, by the way - and Lord alone knows how many supersymmetric or otherwise exotic matter fields into things.)
Basically, if you assume Newtonian gravity, you're driven straight off to a particle explanation of dark matter straight off. But Newtonian gravity is wrong. Then if you accept GR -- and that Newtonian effects are insignificant on galactic scales -- you're also lead to a particle explanation of dark matter. But that's an *assumption*, that relativistic effects are insignificant. They probably are, but if we model the galaxy more accurately, in a cylindrical metric, we get some effects that look a bit like dark matter. It's not enough and the best calculations are still very speculative (even the most firebrand only claim about 33% dark matter this way) but it's still... indicative. If nothing else, why the hell are we adding in arbitrarily new physics before we properly understand the current physics?
Then, let's assume you can only get a 5% dark matter effect from relativistic effects, which I feel would even then be optimistic. People immediately run, again, to a particle explanation for dark matter. But why the hell are we so sure that GR is right? Why do we keep a theory which is actually still fairly poorly tested, in favour of modifying a theory that's relatively well-tested in our particle accelerators? Put it this way: we've tested GR/Newtonian gravity on scales between about 10 micrometres and the bounds of the solar system. Then we extrapolate that up a few orders of magnitude and pretend it's applicable on galactic scales. Then we extrapolate up *another* six orders of magnitude and pretend it's applicable on cosmological scales. Then we express surprise that something doesn't quite work.
Maybe GR properly describes gravity. But we haven't actually tested that! And observations disagree with the assumption. Do we... invent things to explain the observation, or do we at least question our theory of gravity? Do I add in a bunch of unobserved superpartners simply because one of them would be a stable dark matter particle, or do I slightly modify a potentially inaccurate theory of gravity? Personally, I want to check both. Unfortunately a lot of researchers are focusing on the former, not least because a large number of themare better than I -- much, much, much better than I -- at particle physics and at observations assuming Minkowski space, but worse than I at relativity.
Anyway, that was a long rambling rant :) But I just feel that adding massive neutrinos -- and neutrinos *are* massive; there are at least three species, and at least two of them have mass. If we believe any of our current particle physics, that is unescapable -- and modifying gravity is preferable to adding a plethora of unobserved arbitrary fields and tweaking one of perhaps 130 free parameters. Others feel differently and may very well be proven right, in which case excellent. At least we've also exhausted alternatives.
You are conveniently ignoring all the advances of science that gave us the means to do things that nobody even imagined were possible before them.
Do bosson condensates really only appear at extreme cases? That depends, if your bossons are phonons, no, they don't. The same aplies to fermions, if they are electrons... The entire semiconductor and material technologies come from this fact.
Newton laws added a bunch of restriction on what physics alowed, that is true. And the machines from the early Industrial Revolution came from those restrictions. Before him designing a machine needed several lifes of working, after we knew those restrictions people could design several machines at their working lifes.
Also, an incredible discovery is way more likely than you imply. Current physics is simply wrong, we know that. Nobody knows what will came from that discovery, but it is unlikely that no new thing will.
Rethinking email
Thanks for the speculations, and I'd encourage you to try some back on an envelope order-of-magnitude calculations to see which might make sense. For example, get a figure for the energy of an atomic bomb in some unit, and then find out the energy the sun puts out in one second in the same unit, and compare them.
Also, what may seem to make sense with today's physics might seem ludicrous with tomorrow's physics.
Maybe the sun is indeed a ball of iron.
http://www.thesunisiron.com/
Or maybe cold fusion takes place at the Earth's core at the edge of a nickel-iron core?
http://aleklett.wordpress.com/2011/05/16/the-sun-rossi%E2%80%99s-%E2%80%9Denergy-catalyzer%E2%80%9D-and-the-%E2%80%9Cneutron-barometer%E2%80%9D/#comment-5891
Or maybe we will tap zero-point energy reliably one day?
http://en.wikipedia.org/wiki/Zero-point_energy
Or the universe is mostly shaped by electrostatics?
http://www.electricuniverse.info/Electric_Sun_theory
Or the universe is a simulation:
http://www.simulation-argument.com/
And so on.
"Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand. (Albert Einstein)"
Hope you keep imagining things. And think about ballpark calculations. And still hold on to your "roots" in humanity and day-to-day things like sunshine, vegetables, and laughter even when having imaginative "wings".
A 21st century issue: the irony of technologies of abundance in the hands of those still thinking in terms of scarcity.
There will never be any interstellar trade. The distances and velocities involved require energy expenditures vastly higher than the cost of any valuables you may wish to transport.
Sounds a little like someone saying "Man will never fly" in the 1300s...
There's actually a pretty big difference. In the 1300s anyone doubting the ability of man to fly could look to birds, insects, and bats as proof that flight is at least possible. If they could do it, maybe we could too.
OTOH, we have no examples of interstellar travel that we can look to as proof it can be done.
We hope your rules and wisdom choke you / Now we are one in everlasting peace
Yeah.. but we're adding new particle physics on the understanding that Newtonian gravity is sufficient. It's not. We're also doing so on the understanding that our application of GR is also sufficient. It's not. I'm not a galactic dynamicist; I'm a cosmologist. The dark matter in my field is seen in the Friedman equations which, regardless of whether they're valid or not, are from a naive application of GR on (at least) Gpc scales, assuming homogeneity and isotropy. This may or may not actually be valid, not least because it involves a whole collection of undefined uses of the phrases "on average" and "on large scales". Assuming "on average" that the universe is homogeneous and isotropic does lead to the FLRW metric; that's true. Maybe that's even actually a true assumption and that "on large scales" FLRW is an accurate description of the universe -- but even if that's true it's only true for null geodesics and it *isn't* true for the dynamics. The Einstein equations are non-linear, or they'd just be a rephrasing of Newtonian gravity. That non-linearity means that regardless of whether we can talk about "average" quantities in GR (and, currently, *we can't*), and regardless of whether FLRW will hold "on large scales" (and it may very well do and I suspect it does), the dynamics are different from FLRW dynamics.
Quantifying that is, of course, a different matter. Interestingly, so far, the deviations in the dynamics using a naive definition of a scalar average and a rather unsatisfactory averaging on 3-surfaces, have tended to look like dark matter. Does that solve the (cosmological) dark matter problem? Of course not. It would be bizarre to claim it did. Does it suggest that there may at least be something in this idea? Yeah, sure.
But more than that, you can go the other way and avoid questions of averaging at all. Instead, you can take a look at the effects of inhomogeneities in GR. That's remarkably ill-researched given that we tend to stick in Schwarzschild, Reisser-Noerdstrom, Kerr and FLRW metrics (three of which are inhomogeneous). Sure, people are putting in LTB metrics in cosmology now,and a few people are using Szekeres solutions, but it's very under-studied. And if you like dropping the Copernican principle (which many don't, myself included) you can drop a requirement for dark energy, at least.
I don't have a strong point here, but the relativistic effects in cosmological (and astronomical) systems remain badly understood. We work with strong assumptions -- in cosmology, that FLRW is an accurate description and in astrophysics, that Newtonian gravity is applicable -- and very rarely question that properly.
In reality I suspect the "answer", if we ever find one, will be a mixture of things. Will SUSY turn out to be true? God, I hope not, but quite possibly it will. Then that gives us a dark matter particle. Are neutrinos a dark matter? Yes, that's incontrovertible. Are relativistic effects (from inhomogeneities, for instance) significant? Yes, I strongly suspect so. Are seemingly arcane theoretical arguments about averaging actually significant? Yes, I suspect that, too.
I wouldn't say "Dark matter is just better right now". I'd say "a naive model where you put in a totally pressureless fluid is a reasonable approximation to reality but still has issues". LCDM is struggling with a few oddities, with large bulk flows, a seemingly never-ending tower of structures on ever-larger scales (not virially bound, just *there*), remaining issues (on a naive dark matter model) with galaxy formation, cusps at the centre of galaxies, an under-abundance of small satellite galaxies, and a few other issues. On the other hand, while no-one, Milgrom included, would pretend that MOND is anything other than pure phenomenology, you surely have to admit it's pretty fucking impressive that such a simple modification of gravity can fit the dynamics of galaxies at least as well as a collection of dark matter halos. Sure, MOND dies on cluster scales, and very badly. I'd never pretend it's anything other
I find it amusing that everyone in this thread seems to think that we're anywhere *near* the technology for a propulsion system needed to journey to another solar system in a mere 100 years. The fastest we've ever accelerated any object in history (the New Horizons probe) would take more like 80,000 years (and that's just to get to the nearest one, our galactic next-door-neighbor at just 4.2 light years away). And that's not even factoring in added time for the deceleration you would need to actually stop once you got there.
We would have to get to a significant fraction of the speed of light to even dream of getting to another solar system in 100 years. And, so far, that tech only exists in the minds of science fiction writers.
SJW: Someone who has run out of real oppression, and has to fake it.