Do 'Ultracool' Brown Dwarfs Surround Us? 224
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."
Ultracool dwarves... (Score:2)
Re: (Score:3)
As regular brown dwarfs would have you know, "ultracool" brown dwarfs are actually hipster poseurs.
Re: (Score:2)
Re: (Score:2)
Yes, but they've failed the Art of the Star. Maybe they can Giggle at the Gas Giants, but they're no more than Cupcakes compared to other stars who are At the Galactic mean size.
Most importantly, what these brown dwarfs are are MACHOs (Massive Compact Halo Objects), which is a competitor to the WIMP (Weakly Interacting Massive Particle) theory of dark matter. So with this discovery we may begin a WIMPy Wrap-Up.
Re: (Score:2)
Re: (Score:2)
Hear that? That's the sound of in-jokes making a sonic rainboom as they fly over your head.
Re: (Score:2)
Really, I tought the main support for WIMPs come from the early universe theories. But IANAP.
Anyway, I can't see how MACHOs couldn't explain the bullet cluster observations. Would they hit each other at the colision? That's unlikely, knowing that even stars didn't do that.
Re: (Score:2)
Re: (Score:2)
The article doesn't say a word about MACHOs or WIMPs. It does say the cluster is an evidence for dark matter, but not for what kind of it.
Re: (Score:2)
I'm not your stepping stone (Score:3, Insightful)
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.
Re: (Score:3)
I speculate that it wold be worth the course. Depending on the design of one's spacecraft, one could pick up particles that are in orbit of the brown dwarf to use for fuel or other raw materials, and one could use gravity as an assist to accelerate further toward one's destination.
Re: (Score:2)
If you're moving slowly enough that a gravity assist off a Brown Dwarf is worth doing, you're talking about interstellar voyages taking tens of thousands of years.
And if you're taking tens of thousand of years to get to Alphacent, you're doing it wrong. Better to just wait
Re: (Score:2)
I agree with you we should live sustainable on this planet and having a space program is not sustainable. Communism is sustainable, but first we need to lower the earth population down to 500 million and segregate humanity into a few giant mega cities. Also we need to wipe out any form of capitalism as if any form of capitalism exists on the planet it will poison the glorious system that is communism.
Then we can live sustainably with nature and stay on this planet and not pollute the cosmos with the huma
Re: (Score:2)
Game over, Troll.
100 Year Travel Time... (Score:2)
Q. What are the odds that 50 yrs of technological progress would slash the stellar travel time, so that a 100-yr trip would likely be pointless?
Re: (Score:3)
Re: (Score:2)
Q. What are the odds that 50 yrs of technological progress would slash the stellar travel time, so that a 100-yr trip would likely be pointless?
A. Not good.
Re: (Score:3)
If the Brown dwarf had some transverse velocity to the direction that you wanted to go,you could use it as a gravitational slingshot to gain speed and hence time with minimal or even possibly no fuel usage.
Re: (Score:2)
No you could establish colonies along the way on these brown dwarfs. They may be small enough that you could scoop up hydrogen from them for fueling and some may even have planets orbiting around them which would allow for colonization of them.
Define 'stop' (Score:3)
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.
100 year journey--yeah, in our dreams (Score:3)
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 o
Racist (Score:5, Funny)
Re: (Score:3, Insightful)
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.
African American little people with sunglasses.
You can't be ultracool without sunglasses.
Re: (Score:2)
Re:Racist (Score:5, Funny)
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.
Mass disadvantaged stars of color.
Re: (Score:3, Funny)
Face it, white man. Even our short guys get more than you do.
Re: (Score:3)
It's not just slashdot. It's the entire astrophysicist community.
We should never forget "Black Holes" that destroy anything that come close enough - that's both racist and sexist.
Does it matter to dark matter? (Score:2)
Re: (Score:2)
Would these ultra cool brown dwarves serve in putting more fruit to dark matter theories?
Almost certainly not. Dark matter made up of brown dwarfs was searched for in the gravitational microlensing experiments like the MACHO project [anu.edu.au]. They didn't find nearly enough to account for the dark matter.
Re: (Score:2)
Re: (Score:3)
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 [arxiv.org] 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 w
Re: (Score:2)
No. Brown dwarf stars are made of baryonic matter, just like you and I. Dark matter must be non-baryonic, or physics needs to be totally redone. (A difficult job, as coming up with even one chunk of math that matched what we know of quantum behavior took lots of work.)
Basically, current physics predicts the number of protons+neutrons created at the time of the "big bang", and thus the number of baryons in the universe. There aren't enough of them to account for the "dark matter". And all current altern
Yes there are (Score:3, Informative)
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.
Re:Yes there are (Score:5, Informative)
Large stars will never become brown dwarfs. They will end up as one of the following:
White dwarf, neutron star, or black hole. A white dwarf will eventually cool and become a black dwarf. The chemical composition of a white dwarf is NOTHING like that of a brown dwarf. A brown dwarf is hydrogen and a few other elements. A white dwarf has very little hydrogen, it is the 'ash' of a star that once was and is made of mostly heavier elements that are the result of fusion.
Re: (Score:2)
No, it's mass is far too small. I know how ropy Wikipedia is as a source, but the page on brown dwarfs [wikipedia.org] is pretty good.
Re: (Score:2)
Mods, this isn't informative.
Large stars do not become brown dwarfs. Brown dwarfs don't have solar winds. Brown dwarfs aren't Earth size - they are many times larger than Jupiter. Nemesis is a piece of fiction - it hasn't been ruled out but there's no evidence at all for it's existence. If Nemesis did exist, it would be throwing comets at us, not asteroids, and they would come from within our solar system.
Re: (Score:2)
I think it's been decided that Nemesis "probably doesn't exist". At least in the form originally hypothesized. But there are tentative signs that *something* exists that does approximately what it was proposed that Nemesis would do. Tentative is far from proof, however, and "something" could cover everything from a black hole to a large planet in an eccentric orbit. Depending on how much of the evidence you wish to attribute to chance. (Some of it clearly is, but how much? And we can't tell. Besides,
Hmmph. (Score:3)
All foam, no beer (Score:5, Interesting)
Re: (Score:3, Interesting)
Re: (Score:2)
I understand that, however I wonder if a 'refueling' is possible within the constraints of near-future (100 or so years) technology.
What I could see happening is setting up waypoints or space stations near the stars which are used much like the forts were during colonization of North America.
Re: (Score:2)
Survivable (with shielding) surface temperatures and an abundance of Hydrogen for one.
If theres something that can function as a gas station in between us and Proxima Centauri the trip might become possible.
Re: (Score:2)
The article claims that they hope to find some with an exterior temperature below 225 C! For comparison, the earth's outer core ranges from 4400 C in the outer regions to 6100 C near the inner core, and the inner core is around 5400 C.
Re: (Score:3, Interesting)
Instead of building a colony ship that can travel a minimum of 4 ly to the next star system, you can build one that only needs to go 0.1 ly (or so, depending on the density of these things). That's a vastly simpler job, requiring much less time and energy, and possibly only taking a decade or so --- well within a human lifespan. Once you get to the brown dwarf, you colonise. Even a small brown dwarf like Jupiter has an insane amount of resources. Sure, there's no starlight, but if you've got hydrogen you ca
Re: (Score:2)
Unless there are a bunch of these closer than the nearest stars we can see, they'd make poor stepping stones. However, their existence suggests that other cold objects (icy, not pizza-oven hot like these things -- think Oort cloud or Kuiper belt objects like Sedna and Eris) may be more prevalent than previously thought. Those would make good stepping stones.
The stepping-stone concept assumes we'll never have FTL transport or even significant-fraction-of-lightspeed transport. (Bussard ramjets may be harde
Fuel is my first thought (Score:2)
Refueling... Even with the best drive, you don't want to carry all your fuel with you. A quick circling stop there could boost speed and pick up more fuel, not to mention much needed gravity vacation.
Re: (Score:2)
You're aware that it takes fuel to stop there, right?
And then it'll take the same amount of fuel you used when you left the Solar System to get back up to speed when you leave the Brown Dwarf, right?
And the same amount of fuel to stop when you get where you're going ultimately as it took to stop at the Brown
JWST, Mass (Score:3)
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?
Re: (Score:2)
Re: dark matter, apparently not. http://science.slashdot.org/comments.pl?sid=2332984&cid=36800042 [slashdot.org]
Re: (Score:2)
I agree whole-heartedly on the comment about JWST. It was an enormous eater of funds, but the science potential was even bigger.
Regarding the dark matter issue, there is a small minority in the astrophysics community that believe these sorts of so-called Massive Compact Halo Objects (MACHOs, a name chosen to specifically counter Weakly Interacting Massive Particles or WIMPs) might make up the dark matter.
The majority of the community is in pretty solid agreement that dark matter must be something more exot
I've suspected this... (Score:2)
I've suspected this since Gary Coleman and Emmanuel Lewis were first detected in the 1980s.
Not useful as refueling dumps? (Score:3)
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.
Could we blow them up? (Pure speculation). (Score:5, Interesting)
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"?)
Imagination is more important than knowledge (Score:3)
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/ [thesunisiron.com]
Or maybe cold fu
Re: (Score:2)
They remind a bit me of this book, which I think you'd like, by James Hogan:
Kicking The Sacred Cow (Questioning the Unquestionable and Thinking the Impermissible) [amazon.com]
Two excerpts from a review:
In his introduction, "Engineering and the Truth Fairies," Hogan describes the ideal view of science, but points out that even scientists will accept findings in fields other than their own without skepticism. He states: "I used to say . . . that science was the only area of human activity in which it actually matters whether or not what one believes is true. . . . Today, I reserve that aphorism for engineering" (p. 9).
He makes the point that since engineering deals directly with reality, it is a useful gauge to the truth of scientific theories.
In his afterword, "Gothic Cathedrals and the Stars," he notes that many of the most important findings in science over the past several centuries were actually made by outsiders, from Leonardo da Vinci (who was trained as a painter) to Albert Einstein (who was working as a patent clerk when he made many of his most important findings). He observes: "While most research today depends ultimately on government funding . . . history shows that bureaucratic stifling and an inherent commitment to linear thinking makes officially inaugurated programs the least productive in terms of true creativity" (p. 466).
It is a scathing analysis of modern science, but one that is not undeserved.
Re: (Score:2)
A meteoroid with enough impact power to equal the largest nuclear bomb we have ever made impacts the earth roughly every thousand years or so. So, any brown dwarf that could be ignited by a bomb would be ignited already by stray impactors.
I suppose one could set up a scenario where a bd had, over the eons, been heating up little by little due to external forces and was now only one bomb away from ignition. But again, if it were that close to going stellar, then any ol' starquake, or maybe even tidal force
Re: (Score:2)
Re: (Score:2)
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?
"Fusion" bombs fuse Deuterium and Tritium. Brown dwarfs already fuse Deuterium and Tritium for the part of their life cycle. That's what makes them brown dwarfs and not planets.
http://cronodon.com/SpaceTech/BrownDwarf.html [cronodon.com]
In order to create a real star, you need proton fusion. But that requires maintaining necessary heat and pressure for millions of years. If the gravity of the brown dwarf and the native deuterium and tritium couldn't do it then it is unlikely that your puny little H-bomb is going to
Re: (Score:2)
Refueling wouldn't incur slowing the ship down...it would involve sending an automated factory out to the brown dwarf in advance, which would gather matter and launch it at high speed into the flight path of the refueling vessel. If necessary, rockets on the payload could be used to match the exact velocity.
YES!!! This is exactly what I've been saying! (Score:2)
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
Re: (Score:2)
And further, maybe someday we'll also be able to tap zero-point energy and create matter and energy in the middle of apparently empty space.
http://en.wikipedia.org/wiki/Zero-point_energy [wikipedia.org]
I can wonder if planets and asteroid orbiting brown dwarfs far away from the turmoil of the galaxy and other stars might be and ideal place for life, same as there is a lot of variety of life in the rarely disturbed deep ocean. The closer you live to a galactic core, the bigger the chance for periodic supernov
statistically speaking (Score:2)
star formation results in a range of star sizes. some sizes are below ignition threshold. we don't see them, simply because they're dark. but, statistically speaking, there should be a lot more failed stars than ignited stars. so take a random section of space, count the number of stars you can see in that, and there should be a mathematical relationship between the number of visible stars, and the number of invisible unignited smaller "stars". and this relationship should be proportional by orders of magni
Perhaps... (Score:2)
...these objects represent some of the "dark matter" we are searching for?
Re:fp (Score:5, Interesting)
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 [wikipedia.org]...
Re: (Score:2)
SURROUNDED BY ULTRA-COOL BROWN DWARFS? (Score:2)
What, an army of midget JJ " Walkers? [youtube.com]
Re: (Score:3)
Ultra-cool brown dwarf? How about p-diddy?
Re:The only thing that surprises me is surprise (Score:4, Informative)
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...
Re:The only thing that surprises me is surprise (Score:4, Insightful)
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.
Re: (Score:2)
The fact that we can't even prove or disprove that a brown dwarf orbits our own star demonstrates that our 'accuracy' about our local neighborhood can't be all that
Re: (Score:2)
Re:The only thing that surprises me is surprise (Score:4, Interesting)
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.
Re: (Score:2)
Please stop before you hurt yourself.
We know roughly how much the galaxy weighs (although that number has some pretty big error bars and is refined on a regular basis). We've got a rough idea of how much luminous matter (stars) there probably is in the galaxy by extrapolation (we can't see the whole galaxy), and we can't even see all the luminous matter, especially that's even a little ways away. Astronomers are very aware of this.
Nevertheless, gravity provides a pretty good way of measuring the mass of t
Re: (Score:2)
I know I'm a layperson, but I think astrophysics really needs to move beyond the assumption that if we can't see it it isn't there. The more closely we're able to study space the more we find that it's full of stuff of every size at every conceivable distance. I honestly thing it's safe at this point to assume that nearly every star has planets as a simple matter of the nature of stellar accretion processes, and further that for every star that's bright enough to see there are probably a dozen too dim. This is why we can't figure out dark matter/energy.
If the arrangement of discovered exoplanets has taught us anything, it's that most of our safe classic assumptions need to be wadded up and thrown in the nearest dustbin. And yes you are a layperson who probably knows nothing about the practice of astronomy or astrophysics, or high energy physics. It's not a matter of "seeing" or 'not seeing". If something exists it makes it's imprint, it's footprint in the universe around it, in the gasses it's thrown off, it's interaction with other things or just th
Re: (Score:2)
Re: (Score:2)
Like ghosts and deities, presumably?
Re: (Score:2)
"I think astrophysics really needs to move beyond the assumption that if we can't see it it isn't there"
Disclaimer: I am an astrophysicist and I get the impression one or two others replying to you either are, or are very well-informed laymen themselves.
My brief comments: Firstly, there are plenty of people - thousands of them - who are highly educated and thinking about this professionally. Not meaning to sound arrogant, but it's pretty damn unlikely that you'll think of something that someone else hasn't,
Re: (Score:2)
Provocatively stated but I do tend to agree anyway. Well, except the stuff about the DSM-V. Also I think these Space Nutters themselves number in about the hundreds, and are pretty much harmless.
Re: (Score:2)
To be honest, I have no idea what the "DSM-V" stuff is referring to. The people I've encountered like this... harmless. Sometimes annoying, but harmless. Asking me weird questions at conferences, but harmless. I don't care if people believe NASA claims it invented a lot of current technologies. In some cases it's even got a point, and in the rest, people can believe what they want. There are plenty of people believe that moon landings never happened - and I'm willing to believe that there are as many of the
Re: (Score:3)
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.
Re: (Score:2)
It's off-topic but you *can* fit the bullet cluster with a theory of modified gravity and at least one species of massive neutrinos (and we have at least two species of massive neutrinos in nature) so long as they're sufficiently massive. It was a major blow against TeVeS that it couldn't fit the bullet cluster... and then it was found that actually it could if you add in a well-motivated species of warm dark matter which is definitely in existence.
This shouldn't be taken too strongly. I don't think anyone
Re: (Score:2)
Re: (Score:3)
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 i
Re: (Score:2)
As for adding ne
Re: (Score:3)
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, no
Re: (Score:2)
You don't understand Occam's razor.
Newtonian mechanics is simpler, but doesn't explain all the data. Relativity is more complex, yes, but it DOES explain all the data. The principle of parsimony suggests that if we're presented with two explanations that both explain the observations then we pick the simpler.
If you just modify gravity it's arguable whether that change is simpler than postulating non-baryonic dark matter or not. But modified gravity doesn't explain the observations. You have to modify gr
Re: (Score:2)
Ah, modified gravity gets better and better.
To fit the data (ALL the data) you need to modify gravity, have neutrinos with an unlikely amount of mass AND have non-baryonic dark matter.
Or you can just have non-baryonic dark matter.
Re:Slingshot? (Score:5, Interesting)
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.
Re:Slingshot? (Score:4, Insightful)
Re: (Score:2)
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. Why say "never?" when it's such a long time, includes technology you can't ever imagine? Why not say "within our lifetimes?"
The only movement between stars will be radio signals and initial colony ships.
The RIAG (recording industry artists of the galaxy) will do their best to insure that you can't buy hypermusic over 5D reversible radio signals, but it happens eventually and will constitute interstellar trade. I mean, that's what I would say if I were a time traveler. Which I'm not.
Re: (Score:3)
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.
Re: (Score:2)
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.
Not true. We do have examples of interstellar travel as proof of concept. Light itself undergoes interstellar travel all the time. Now, making the conceptual link between the transit of light and the transit of matter may seem impossible to us today, but no more so than the link between the creatures of the air and mankind would have done to twelfth century philosophers. And for smaller distances, we have comets and meteors to look to for proof of concept.
Re: (Score:2)
We just have to look at any bit of matter that isn't hydrogen (and maybe some helium). It has all originated from some supernova outside our solar system. Since it is here, it must be possible to exchange matter, and a considerable amount, with other systems. The time scale of such trade may be quite long, but it does show that is possible on a grand scale.
Re: (Score:2)
Assuming there is no physics breakthrough that explains phenomena like quantum entanglement, that is.
Re: (Score:3)
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 R
Re: (Score:2)
No, no point. But it might speed up the discovery of systems with so many precious metals they pay you to take them away. I think we should look at Cemeiss.
Re: (Score:2)
Willy Wonka is a racists bastard, he tool those poor oompa-loompas from their natural environments and forced them to live in a city that was alien to them. Exploiting them for their manual labor. Willy Wonka is essentially a slave master and the oompas are his slaves.
I wonder if he goes down the breeding quarters in the deep bowels of his factory to help himself to some of the orange and green "oompa-tang", he probably has a special oompa-loompa abortion center there to help conceal his half-breed mutan
Re: (Score:2)
Re: (Score:2)