information can flow both directions in time. The future influences the past in exactly the same way that the past influences the future.
... is more than a little spooky. Time-reversible relativistic laws of physics are nothing new. In fact that's pretty much every law we have with the 2nd Law of Thermodynamics being the only apparent indication/cause of the arrow of time. But Relativity also assumes causality, cause preceeding effect.
How is this compatible with relativity if we have information going backward in time? That's not less spooky than interactions appearing to break out of the light cone, a concept and problem that only exists as a consequence of the assumption of causality!
Can you re-derive Special Relativity without the assumption of causality? Or is there some aspect of this theory that prevents the causal loops that backward-flowing information would seem to allow, much like how you can't break causality with quantum entanglement?
I guess the first question would be: Is this actually a theory, as in makes testable predictions beyond the standard formulation of quantum mechanics, or is it an "interpretation", a philosophical explanation and mathematical treatment that arrives at the same results but with a different underlying assumption of what QM means?
Not true: tests of Bell's inequality have only ruled out some very limited classes of hidden variable theories. There are still lots of them that are very much on the table.
Specifically local hidden variables, as in ones that would obey the speed of light and get rid of the "spooky action at a distance" that inspired Einstein et. al. to write the EPR Paradox paper claiming quantum mechanics had to be incomplete.
The experimental violation of Bell's Inequality means that while there may be some kind of hidden variable, it can't be a kind that gets rid of the quantum weirdness.
It's often been pointed out that, although standard QM does predict weak measurements should work, it's unlikely anyone would ever have discovered that if time reversible QM hadn't made the prediction first.
Yes, I know, it's because of the travesty that is DMCA, but that doesn't make it any less silly.
No, no, of course not, but it does mask it. Like, a man wearing a tutu, bunny slippers, and a singing Billy Bass as a hat is pretty fucking silly. But put that man on a giant merry-go-round with a troupe of nuns yodeling the dictionary backwards, an upside-down pie-eating contest, a poo-flinging monkey in a pope outfit on stilts, and so on, and suddenly the guy in the tutu doesn't stand out so much.
Of course the rational response to all this silliness is to bulldoze the entire merry-go-round into a big hole and cover it with hot tar.
Thats a great strategy only problem with it is from TFA the indication they received was noticing it was not behaving the way it was supposed to be behaving. They had to look around to figure out why.
Yes, because normal operations were suspended.
You don't have to assume anything. You KNOW the block is invalid. A bad block should not cripple the computer so that it can't do anything else. There is no indication from TFA there were any other faults.
No, you don't. You don't know if the block is bad, if the data bus is suffering an intermittent fault that happened to occur while that block was being read, if it's the BIST or ECC mechanisms that are faulty, or if it's a software error corrupting the data. Going from "we got a fault on reading this block" to "that block and only that block is affected, let's get on with it" with no consideration is a great way to lose a rover.
All I do is write software and I refuse to follow this shitty advice. Every error should be checked and handled. Besides the fricking hardware does all the heavy lifting for us
Ah, so you only allow your software to be run on hardware with ECC corrected RAM and ECC caches and ECC data busses... seems weird to call this a "PC app" when it's excluding most of the PC market. Unless you're doing it yourself then you're only checking for a subset of errors.
Now, assuming it's one that you can see, how do you "handle" that error? Do you just not read from that file again but continue on under the assumption that it was a singular event of no further consequence? Or do you have the software notify you so you can identify what the actual source of the read error was?
The former, I presume, which is fine for the situation of a PC app. Just let the hardware do the heavy lifting, and don't worry about what it can't find, and don't worry about what errors it signals actually mean. If it's a more serious error that ends up causing rampant corruption, it's not your problem! Contact your OEM, your help desk can tell them.
We're talking about I/O failure to flash not crashing an OS or broken hardware.
So, you don't see how an I/O failure could cause an OS to crash, like say if it's reading a code page, and you're still assuming that an ECC error on reading a block of flash can only mean that it's the ram cell itself and only that ram cell that could be affected? You're willing to bet 2.5 billion dollars and the rest of the mission on these assumptions?
Okay.
From TFA this is exactly what they did do...they waited to notice the rover not doing what it was supposed to be doing.
Which is a consequence of the rover doing what it should be doing -- ceasing normal activities on detecting a fault. We're talking about what the rover should be doing -- assume it's a one-off fault and continue normal operation minus that one block as you would have it, or try to prevent anything else bad from happening by going into safe mode (!= sleep mode, btw) and waiting for ground control to figure out the problem.
"We have probably several days, maybe a week of activities to get everything back and reconfigured."
Yes, and? Are you quibbling over "couple" vs "several" -- is this attempted pedantry, or are you actually implying that a couple days is fine, but waiting a week to finish the historic first-time analysis of an interior rock sample on Mars to make sure it has the maximum chance of success instead of bricking the rover crosses the line?
Ok lets assume a cosmic ray corrupted some random block of flash memory...so what? Why should that lead to failure to upload anything or enter sleep mode?
Pretty much any fault, error, or out-of-bounds reading with any part of the rover causes it to stop whatever it is doing and wait for ground control to check it out and decide what to do. If the fault is with the computer itself, it makes sense to gracefully enter safe mode. It probably was a cosmic ray flipping a random bit, but you can't assume that when designing your fault handler.
If it were any old PC app this would be perfectly acceptable behavior. However for ultra expensive spacefaring things I would expect it to be designed to still try and be useful even if the southbridge cought fire.
See, I think you have that backwards. If it were a PC app it would be appropriate to just assume the error was insignificant or more likely not bother checking in the first place. If it's a more serious problem then eventually the app or OS might crash, the user will reboot, and if that doesn't work reinstall, and if not that then they'll just go get some new hardware.
For a multi-billion rover on another planet, you don't want to just wait and see what happens. Any anomaly at all should be cause for cautious, deliberate action. Heck, the whole project is run that way.
The rover was designed with a lot of redundancy and flexibility so that it can be useful even in the face of more serious problems, and if that turns out to be the case they'll find a way to make the rover as useful as possible. Missing a couple night's worth of downloads and delaying some activities in order to take the time to make sure they're maximizing the rover's future potential is an easy tradeoff.
in typical typical slashdotter fashion, you didnt even read it before replying did you?
Of course I read it. And all I saw was you saying that you "got dealt some shitty hands"; nothing about mental illness.
And I assumed that this "shitty hand" was something else, because if it was mental illness you were talking about and you actually understood mental illness, you wouldn't have said something so fucking stupid.
nytime someones says anything other than "people with mental illness are completely helpless"
But you didn't say just anything other than that. You said they had complete control and can just pick themselves up and dust themselves off and move on. Which is a fucking stupid way to say "they aren't completely helpless" because that's not the same thing.
So dont tell me I dont understand and have never thought about it.
What you said demonstrates that you don't, so tough shit, I'm telling you that you don't. You understand your own journey, which I don't know or care about. As a generalization, as a statement intended to demonstrate understanding of mental illness and others who suffer from it, "you have complete control of how you play that hand" is stupid and wrong.
What the AC said as to why the SMBH can't explain the galaxy rotation curve -- the problem is that the curve is flat, meaning the orbital velocity doesn't decrease with distance from the center as one would expect regardless of the amount of mass at the center. See the graph on the right, here. All increasing mass at the center would do is change the values on the Y-axis. The curve shape would be the same.
As far as measuring the relativistic mass goes -- turns out that's easy! Put an object on a scale, and you are measuring its relativistic mass. Measure the gravitational force exerted on some object by another, and you are measuring it's relativistic mass. All of your everyday notions of what "mass" means and the ways in which you measure mass are measuring relativistic mass.
It's actually figuring out the intrinsic mass that's hard. And for a black hole, it's both impossible and irrelevant. The properties of a black hole do not depend at all on the intrinsic mass of whatever went into it. In fact it was proven that in General Relativity that you can't tell what made a black hole, or what has gone into it since, by observing the black hole. The resulting object is the same regardless. This is called the "no hair" theorem for what I'm sure are hilarious historical reasons.
Light has momentum (which "require" mass in more classical thinking). Light is "moved" by gravity (which indicates mass)
Also light has energy which is mass in Relativistic thinking, and is moved by (and moves other things by) gravity which is due to it's energy (same as mass).
This is confusing because people think of "mass" as the things photons don't have and matter does (which is true if we mean intrinsic mass), but also think of "mass" as the thing which effects/is affected by gravity and makes objects resist acceleration, when that's actually the relativistic mass (= energy).
It's both a particle and a wave, thus *is* a particle.
A photon is a quantum mechanical particle, which is a thingie which behaves kinda like a classical particle and kinda like a classical wave but not exactly like either.
However the key thing about quantum mechanics is that stuff is quantized... like particles are. So we call them particles. There is no misconception in doing so.
Its local gravity is determined by its rest mass not its relativistic mass.
No. Gravity is determined by the stress-energy tensor, and the energy component is total energy, aka relativistic mass (literally, they're the same thing). Relativistic mass is the gravitational mass is also the inertial mass.
A proton's mass -- the ratio between its acceleration and the force exerted by an electric field -- is much higher than the intrinsic mass of the quarks that make it up. It's the kinetic energy of those quarks held together by the Strong Nuclear Force that gives a proton 90% of its mass. The Higgs Field only explains that last 10%.
Similarly the gravity of the sun is far greater than just the intrinsic mass of the quarks and electrons inside it. It's the sum of all energy in the sun.
If you an accelerate an object it gains energy, and therefore (E=mc^2) relativistic mass, and also therefore increased gravity.
Oh, and yes, this means photons have gravity. Not are affected by gravity (though of course they are) but exert it.
Black holes can evaporate in a few billion years, and then their event horizon disappears. So an event horizon is not the end, just some temporary area with slow time.
A black hole of one solar mass will take 10^67 years to evaporate from Hawking Radiation -- and this time is proportional to the cube of the mass, so think about those SMBHs out there with billions of solar masses. That's a mind-bogglingly long time. You might think it's a long time waiting in line at the Department of Transportation, but that's peanuts compared to black hole evaporation...
And that's only after the CMBR has been red-shifted into near non-existence since until then the black hole is absorbing more energy than it is losing.
Though there are in theory primordial black holes (ones created in the moments after the Big Bang) that would have a lifespan measured merely in billions of years.
"Beware of he who would deny you access to information, for in his heart he dreams himself your master".
Commissioner Pravin Lal, "U.N. Declaration of Rights"
What I really love about this quote, aside from it being amazingly insightful, is that it always seemed to turn up just after I'd gotten done refusing to share some piece of tech I'd developed with one of my "allies" because I wanted to have every advantage when I inevitably steamrolled them. It's like Commisioner Lal knew me, man.
Thanks. Last time I related that story, someone just couldn't believe that a class was harder with Maple doing the grunt work. They assumed I just hadn't taken much math so it was the hardest by default. Then tried to impress me with their standard engineering math curriculum.
That said, I personally disagree with the decoupling of civilians from enemy aggressors, as well as the focus on eliminating collateral damage. Sure, it makes you look nice in the papers, but if you're going to war with someone, it should be all-out war.
Also, while I was and am a supporter of what the US did in Iraq, both from a 'remove Saddam' and 'build a relatively healthy, friendly nation,'
Well then you have a problem because while it may be argued that the ends justify the means, that argument falls apart when the means contradict and thus prevent the ends.
All-out-war is over because the political goals of war have changed. You simply cannot fight a war of "liberation" without respecting the civilians. And this was self-evident in the years of complete and utter failure in Iraq. Sure, we didn't engage in "all out war" against a poorly understood collage of insurgent forces because that's a completely ineffective way to fight an insurgency unless you're willing to go the Roman or Mao Tse Tung route and use genocide. Which would have resulted in us "winning" for a definition of "winning" completely different than what we started with. The warfare equivalent of flipping the chessboard. Good job. You "won". Slow clap.
So instead we tied our soldiers' hands with rules of engagement while simultaneously maintaining a flippant attitude toward colateral damage -- enough to "look nice in the papers" back home, but definitely not the ones in Iraq. This was because the people in charge, like you, really would have rather engaged in all-out war but knew they couldn't because of politics at home.
The result was unsurprisingly ineffective as the ranks of insurgents swelled with angry former-civilians (many of whom were former-army, but don't get me started on that).
A lot of people credit The Surge with turning Iraq around, but while a component it was actually the least important part of what changed. Petraeus' real genius was in not only using force even more judiciously than before -- the opposite of what you would do -- but also in fully engaging the civilian population. He didn't treat them as though they were basically the enemy that he couldn't shoot because it looked bad on CNN. He treated them as if they were already allies that required help. He took "winning hearts and minds" seriously, and it worked. When the area of Iraq Petraeus was in charge of stabilized like none of the rest of Iraq had, they put him in charge of the lot so his demonstrably effective (and not coincidently completely unlike your) strategy could benefit everywhere. And it did. Only in the environment created by this new strategy could the additional troops put in have been effective.
You know what the REALLY sad part is? The part that really causes comments like yours make the bile swell up in my throat?
It's that when we began in Afghanistan, the people did support us. Unlike the Iraqi people who felt betrayed by us after Desert Storm, the Afghan people still thought of us as the folks who helped them kick out the Russians. With no love lost for the Taliban, they were actually on our side. At first.
Thanks to years of idiotic management, that flippant attitude towards collateral damage you embody, and years of neglect due to being focused on Iraq, we lost both literal and figurative ground in Afghanistan. We squandered our advantage. Pissed it away. Turned the people against us.
And then some dweeb comes along and says the people "will never support us". As if it was always this way. As if it's their fault, instead of ours. Gee, maybe we should just stop worrying about killing them. That would probably fix it.
Pluto is different in that it has a lot of co-orbitals, and some of them are almost as large as Pluto itself.
To make it clear how big a difference it is, let's look at the ratio of the mass of the body in question to the mass of the rest of the objects in its orbit (discounting direct satellites).
Of the planets Neptune happens to have the lowest such ratio. It outmasses everything else in its orbit by a factor of over 10,000.
Meanwhile Pluto is outmassed by the other objects in its orbit by more than a factor of ten. It is less than 10% of the mass in its orbit.
That's a five order of magnitude difference. "Clearing the orbit" isn't precisely defined... and it doesn't need to be. You don't need a precise definition of where exactly on the beach the ocean begins to know that Asia and North America are separated by the Pacific Ocean.
And I suspect that such a large distinction isn't a cosmic accident, and that other star systems of sufficient age will show a similar trend. Unfortunately it's going to be a long time before we can test this hypothesis.
The sun will become a white dwarf, which is a post-stellar remnant made of electron-degenerate matter (where the electromagnetic repulsion is not sufficient to hold electrons apart against gravity, and instead they're held apart by the Pauli Exclusion Principle) about the size of the earth. Before that, when it ends its Red Giant phase, it will shed much of its mass in novas. Which are gentle events only in comparison to a supernova. "Explosion" is quite fair. Certainly nobody in the solar system watching would say, Crocodile Dundee style, "That's not an explosion..."
The most difficult math course I ever took was my first college math course, Calc II with Maple. Why yes, use of the symbolic calculus program Maple was so important to the class it was in the name. We took our tests at a workstation with Maple on it.
When my adviser suggested I take this version instead of normal Calc II, I didn't hesitate because I naively assumed this would make the class easier.
Turns out that when you remove the time it takes to do the actual mechanics of taking integrals and derivatives, you can instead focus on problems where the difficulty is figuring out how to set up that integral and derivative. Which is much harder than following some rules by rote.
That's why Feynman Diagrams were such a big deal -- they actually allowed physicists to figure out how they should be applying the equations of quantum mechanics to a specific problem. It let them figure out what to calculate. How wasn't the challenge.
I don't know, exactly. I'm assuming it's the same Aristotlean Physics Kook from quite some time ago with a new nick. They had a pretty extensive blog about how Newtonian mechanics was wrong and Aristotlean motion was obviously correct. Seemed like a bit much for just a troll. So, instead, I think it's your run of the mill Internet Crackpot who never studied any physics, came across one puzzling question, decided ignorance + a question + their genius = proving everyone else wrong. The rest is history and irrational slashdot posts.
I am so tired of the 'Mankind's existence is valueless' bravado. We are a billion to one galactic coincidence that has risen to sentient thought and self-awareness.
Well I don't know about how big a coincidence we are, but so what. There might be a trillion sentient species in our galaxy, but so what. None of them are us. Just like there are billions of humans out there besides myself, but none of them are me. "Humanity will still exist" isn't an acceptable excuse for me to neglect my own survival, and "Sentient life forms will still exist" wouldn't be an acceptable excuse to let our species die out.
Bravado, such a perfect word for this. Funny how this kind of bravado is the opposite of the bravery to go on existing. We didn't get here by not wanting to survive.
Bwa ha ha! So glad to know I nailed it the first time. But wait, there is in fact a nuance here that I missed. It's not that they're wasting their time actually doing the research -- even though, you know, that's exactly what you said -- because obviously nobody should give a shit what you think is important to research or not. Obviously.
No, it's that they just shouldn't bother releasing their research until they've converted it into something you think is important.
And of course you think that's not ridiculous.
Since you're a Tardino emitter of intensity equal to the Large Moron Colider, let me explain: Releasing their research is how they make others aware of and interested in their findings, eventually enabling one of them to be the ones who discovers how to turn this into something you'd care about. Science is colaborative, you see, and you never know which other scientist might be the one to make the breakthrough; it might not even be someone who has their degree yet, and is only reading about this on/.. Notice how this is basically the same thing I already said? No matter. Now that I understand your point better, though, I think I can cut down to what you really meant.
You didn't really mean that it's a waste of time to do the research, or publish the research. You said those things, but that's obviously not what you meant.
What you really meant is that they're wasting their time telling you.
Which is also obvious. But not their problem. Don't click the link if you're not interested in things that won't go into your iPhone, you incurious clod.
What didn't I understand? It's a pretty simple point. Research of things occurring on a time frame of billions of years is useless, research of things that will show results in a few decades isn't.
Right? That's almost exactly what you wrote.
And since if you understood that researching things that'll happen billions of years from now could result in unexpected discoveries relevant on the shorter timescale you approve of, but that you don't know this when you begin researching, you never would have written something so stupid, I think I get the point quite well.
Feel free to elaborate. I'm sure there's a deep nuance to your point that I'm missing.
Oh God, not this Aristotlean nonsense again. Nothing keeps or is needed to keep an object in motion. Something (as in a transfer of momentum and energy) is what you need to make an object stop.
It is certainly true that you are not equally clueless as physicists.
Slashdot Mirror
Ah, interesting. But, um, this...
information can flow both directions in time. The future influences the past in exactly the same way that the past influences the future.
... is more than a little spooky. Time-reversible relativistic laws of physics are nothing new. In fact that's pretty much every law we have with the 2nd Law of Thermodynamics being the only apparent indication/cause of the arrow of time. But Relativity also assumes causality, cause preceeding effect.
How is this compatible with relativity if we have information going backward in time? That's not less spooky than interactions appearing to break out of the light cone, a concept and problem that only exists as a consequence of the assumption of causality!
Can you re-derive Special Relativity without the assumption of causality? Or is there some aspect of this theory that prevents the causal loops that backward-flowing information would seem to allow, much like how you can't break causality with quantum entanglement?
I guess the first question would be: Is this actually a theory, as in makes testable predictions beyond the standard formulation of quantum mechanics, or is it an "interpretation", a philosophical explanation and mathematical treatment that arrives at the same results but with a different underlying assumption of what QM means?
Not true: tests of Bell's inequality have only ruled out some very limited classes of hidden variable theories. There are still lots of them that are very much on the table.
Specifically local hidden variables, as in ones that would obey the speed of light and get rid of the "spooky action at a distance" that inspired Einstein et. al. to write the EPR Paradox paper claiming quantum mechanics had to be incomplete.
The experimental violation of Bell's Inequality means that while there may be some kind of hidden variable, it can't be a kind that gets rid of the quantum weirdness.
It's often been pointed out that, although standard QM does predict weak measurements should work, it's unlikely anyone would ever have discovered that if time reversible QM hadn't made the prediction first.
Freaky the way science works sometimes, isn't it?
Yes, I know, it's because of the travesty that is DMCA, but that doesn't make it any less silly.
No, no, of course not, but it does mask it. Like, a man wearing a tutu, bunny slippers, and a singing Billy Bass as a hat is pretty fucking silly. But put that man on a giant merry-go-round with a troupe of nuns yodeling the dictionary backwards, an upside-down pie-eating contest, a poo-flinging monkey in a pope outfit on stilts, and so on, and suddenly the guy in the tutu doesn't stand out so much.
Of course the rational response to all this silliness is to bulldoze the entire merry-go-round into a big hole and cover it with hot tar.
Thats a great strategy only problem with it is from TFA the indication they received was noticing it was not behaving the way it was supposed to be behaving. They had to look around to figure out why.
Yes, because normal operations were suspended.
You don't have to assume anything. You KNOW the block is invalid. A bad block should not cripple the computer so that it can't do anything else. There is no indication from TFA there were any other faults.
No, you don't. You don't know if the block is bad, if the data bus is suffering an intermittent fault that happened to occur while that block was being read, if it's the BIST or ECC mechanisms that are faulty, or if it's a software error corrupting the data. Going from "we got a fault on reading this block" to "that block and only that block is affected, let's get on with it" with no consideration is a great way to lose a rover.
All I do is write software and I refuse to follow this shitty advice. Every error should be checked and handled. Besides the fricking hardware does all the heavy lifting for us
Ah, so you only allow your software to be run on hardware with ECC corrected RAM and ECC caches and ECC data busses... seems weird to call this a "PC app" when it's excluding most of the PC market. Unless you're doing it yourself then you're only checking for a subset of errors.
Now, assuming it's one that you can see, how do you "handle" that error? Do you just not read from that file again but continue on under the assumption that it was a singular event of no further consequence? Or do you have the software notify you so you can identify what the actual source of the read error was?
The former, I presume, which is fine for the situation of a PC app. Just let the hardware do the heavy lifting, and don't worry about what it can't find, and don't worry about what errors it signals actually mean. If it's a more serious error that ends up causing rampant corruption, it's not your problem! Contact your OEM, your help desk can tell them.
We're talking about I/O failure to flash not crashing an OS or broken hardware.
So, you don't see how an I/O failure could cause an OS to crash, like say if it's reading a code page, and you're still assuming that an ECC error on reading a block of flash can only mean that it's the ram cell itself and only that ram cell that could be affected? You're willing to bet 2.5 billion dollars and the rest of the mission on these assumptions?
Okay.
From TFA this is exactly what they did do...they waited to notice the rover not doing what it was supposed to be doing.
Which is a consequence of the rover doing what it should be doing -- ceasing normal activities on detecting a fault. We're talking about what the rover should be doing -- assume it's a one-off fault and continue normal operation minus that one block as you would have it, or try to prevent anything else bad from happening by going into safe mode (!= sleep mode, btw) and waiting for ground control to figure out the problem.
"We have probably several days, maybe a week of activities to get everything back and reconfigured."
Yes, and? Are you quibbling over "couple" vs "several" -- is this attempted pedantry, or are you actually implying that a couple days is fine, but waiting a week to finish the historic first-time analysis of an interior rock sample on Mars to make sure it has the maximum chance of success instead of bricking the rover crosses the line?
Ok lets assume a cosmic ray corrupted some random block of flash memory...so what? Why should that lead to failure to upload anything or enter sleep mode?
Pretty much any fault, error, or out-of-bounds reading with any part of the rover causes it to stop whatever it is doing and wait for ground control to check it out and decide what to do. If the fault is with the computer itself, it makes sense to gracefully enter safe mode. It probably was a cosmic ray flipping a random bit, but you can't assume that when designing your fault handler.
If it were any old PC app this would be perfectly acceptable behavior. However for ultra expensive spacefaring things I would expect it to be designed to still try and be useful even if the southbridge cought fire.
See, I think you have that backwards. If it were a PC app it would be appropriate to just assume the error was insignificant or more likely not bother checking in the first place. If it's a more serious problem then eventually the app or OS might crash, the user will reboot, and if that doesn't work reinstall, and if not that then they'll just go get some new hardware.
For a multi-billion rover on another planet, you don't want to just wait and see what happens. Any anomaly at all should be cause for cautious, deliberate action. Heck, the whole project is run that way.
The rover was designed with a lot of redundancy and flexibility so that it can be useful even in the face of more serious problems, and if that turns out to be the case they'll find a way to make the rover as useful as possible. Missing a couple night's worth of downloads and delaying some activities in order to take the time to make sure they're maximizing the rover's future potential is an easy tradeoff.
in typical typical slashdotter fashion, you didnt even read it before replying did you?
Of course I read it. And all I saw was you saying that you "got dealt some shitty hands"; nothing about mental illness.
And I assumed that this "shitty hand" was something else, because if it was mental illness you were talking about and you actually understood mental illness, you wouldn't have said something so fucking stupid.
nytime someones says anything other than "people with mental illness are completely helpless"
But you didn't say just anything other than that. You said they had complete control and can just pick themselves up and dust themselves off and move on. Which is a fucking stupid way to say "they aren't completely helpless" because that's not the same thing.
So dont tell me I dont understand and have never thought about it.
What you said demonstrates that you don't, so tough shit, I'm telling you that you don't. You understand your own journey, which I don't know or care about. As a generalization, as a statement intended to demonstrate understanding of mental illness and others who suffer from it, "you have complete control of how you play that hand" is stupid and wrong.
What the AC said as to why the SMBH can't explain the galaxy rotation curve -- the problem is that the curve is flat, meaning the orbital velocity doesn't decrease with distance from the center as one would expect regardless of the amount of mass at the center. See the graph on the right, here. All increasing mass at the center would do is change the values on the Y-axis. The curve shape would be the same.
As far as measuring the relativistic mass goes -- turns out that's easy! Put an object on a scale, and you are measuring its relativistic mass. Measure the gravitational force exerted on some object by another, and you are measuring it's relativistic mass. All of your everyday notions of what "mass" means and the ways in which you measure mass are measuring relativistic mass.
It's actually figuring out the intrinsic mass that's hard. And for a black hole, it's both impossible and irrelevant. The properties of a black hole do not depend at all on the intrinsic mass of whatever went into it. In fact it was proven that in General Relativity that you can't tell what made a black hole, or what has gone into it since, by observing the black hole. The resulting object is the same regardless. This is called the "no hair" theorem for what I'm sure are hilarious historical reasons.
Light has momentum (which "require" mass in more classical thinking). Light is "moved" by gravity (which indicates mass)
Also light has energy which is mass in Relativistic thinking, and is moved by (and moves other things by) gravity which is due to it's energy (same as mass).
This is confusing because people think of "mass" as the things photons don't have and matter does (which is true if we mean intrinsic mass), but also think of "mass" as the thing which effects/is affected by gravity and makes objects resist acceleration, when that's actually the relativistic mass (= energy).
It's both a particle and a wave, thus *is* a particle.
A photon is a quantum mechanical particle, which is a thingie which behaves kinda like a classical particle and kinda like a classical wave but not exactly like either.
However the key thing about quantum mechanics is that stuff is quantized... like particles are. So we call them particles. There is no misconception in doing so.
What you said was quite correct.
I'm not sure what they were saying. I think maybe they meant to reply to justthinkit who was actually proposing an alternative?
Its local gravity is determined by its rest mass not its relativistic mass.
No. Gravity is determined by the stress-energy tensor, and the energy component is total energy, aka relativistic mass (literally, they're the same thing). Relativistic mass is the gravitational mass is also the inertial mass.
A proton's mass -- the ratio between its acceleration and the force exerted by an electric field -- is much higher than the intrinsic mass of the quarks that make it up. It's the kinetic energy of those quarks held together by the Strong Nuclear Force that gives a proton 90% of its mass. The Higgs Field only explains that last 10%.
Similarly the gravity of the sun is far greater than just the intrinsic mass of the quarks and electrons inside it. It's the sum of all energy in the sun.
If you an accelerate an object it gains energy, and therefore (E=mc^2) relativistic mass, and also therefore increased gravity.
Oh, and yes, this means photons have gravity. Not are affected by gravity (though of course they are) but exert it.
Black holes can evaporate in a few billion years, and then their event horizon disappears. So an event horizon is not the end, just some temporary area with slow time.
A black hole of one solar mass will take 10^67 years to evaporate from Hawking Radiation -- and this time is proportional to the cube of the mass, so think about those SMBHs out there with billions of solar masses. That's a mind-bogglingly long time. You might think it's a long time waiting in line at the Department of Transportation, but that's peanuts compared to black hole evaporation...
And that's only after the CMBR has been red-shifted into near non-existence since until then the black hole is absorbing more energy than it is losing.
Though there are in theory primordial black holes (ones created in the moments after the Big Bang) that would have a lifespan measured merely in billions of years.
"Beware of he who would deny you access to information, for in his heart he dreams himself your master".
Commissioner Pravin Lal, "U.N. Declaration of Rights"
What I really love about this quote, aside from it being amazingly insightful, is that it always seemed to turn up just after I'd gotten done refusing to share some piece of tech I'd developed with one of my "allies" because I wanted to have every advantage when I inevitably steamrolled them. It's like Commisioner Lal knew me, man.
You have no control over the hand you are dealt.
But you have complete control over how you play that hand.
Spoken like someone who doesn't understand and hasn't even really thought about mental illness.
Hint: The thing you think gives you "complete control" is the thing affected by the disease.
If a tree falls in the woods and no-one is there to hear it, is the next tree to fall guilty of plagiarism?
Okay, but don't complain about a fact that even in a world where the military was managed and utilized ideally would still be true.
Thanks. Last time I related that story, someone just couldn't believe that a class was harder with Maple doing the grunt work. They assumed I just hadn't taken much math so it was the hardest by default. Then tried to impress me with their standard engineering math curriculum.
That said, I personally disagree with the decoupling of civilians from enemy aggressors, as well as the focus on eliminating collateral damage. Sure, it makes you look nice in the papers, but if you're going to war with someone, it should be all-out war.
Also, while I was and am a supporter of what the US did in Iraq, both from a 'remove Saddam' and 'build a relatively healthy, friendly nation,'
Well then you have a problem because while it may be argued that the ends justify the means, that argument falls apart when the means contradict and thus prevent the ends.
All-out-war is over because the political goals of war have changed. You simply cannot fight a war of "liberation" without respecting the civilians. And this was self-evident in the years of complete and utter failure in Iraq. Sure, we didn't engage in "all out war" against a poorly understood collage of insurgent forces because that's a completely ineffective way to fight an insurgency unless you're willing to go the Roman or Mao Tse Tung route and use genocide. Which would have resulted in us "winning" for a definition of "winning" completely different than what we started with. The warfare equivalent of flipping the chessboard. Good job. You "won". Slow clap.
So instead we tied our soldiers' hands with rules of engagement while simultaneously maintaining a flippant attitude toward colateral damage -- enough to "look nice in the papers" back home, but definitely not the ones in Iraq. This was because the people in charge, like you, really would have rather engaged in all-out war but knew they couldn't because of politics at home.
The result was unsurprisingly ineffective as the ranks of insurgents swelled with angry former-civilians (many of whom were former-army, but don't get me started on that).
A lot of people credit The Surge with turning Iraq around, but while a component it was actually the least important part of what changed. Petraeus' real genius was in not only using force even more judiciously than before -- the opposite of what you would do -- but also in fully engaging the civilian population. He didn't treat them as though they were basically the enemy that he couldn't shoot because it looked bad on CNN. He treated them as if they were already allies that required help. He took "winning hearts and minds" seriously, and it worked. When the area of Iraq Petraeus was in charge of stabilized like none of the rest of Iraq had, they put him in charge of the lot so his demonstrably effective (and not coincidently completely unlike your) strategy could benefit everywhere. And it did. Only in the environment created by this new strategy could the additional troops put in have been effective.
You know what the REALLY sad part is? The part that really causes comments like yours make the bile swell up in my throat?
It's that when we began in Afghanistan, the people did support us. Unlike the Iraqi people who felt betrayed by us after Desert Storm, the Afghan people still thought of us as the folks who helped them kick out the Russians. With no love lost for the Taliban, they were actually on our side. At first.
Thanks to years of idiotic management, that flippant attitude towards collateral damage you embody, and years of neglect due to being focused on Iraq, we lost both literal and figurative ground in Afghanistan. We squandered our advantage. Pissed it away. Turned the people against us.
And then some dweeb comes along and says the people "will never support us". As if it was always this way. As if it's their fault, instead of ours. Gee, maybe we should just stop worrying about killing them. That would probably fix it.
So fucking sad.
Pluto is different in that it has a lot of co-orbitals, and some of them are almost as large as Pluto itself.
To make it clear how big a difference it is, let's look at the ratio of the mass of the body in question to the mass of the rest of the objects in its orbit (discounting direct satellites).
Of the planets Neptune happens to have the lowest such ratio. It outmasses everything else in its orbit by a factor of over 10,000.
Meanwhile Pluto is outmassed by the other objects in its orbit by more than a factor of ten. It is less than 10% of the mass in its orbit.
That's a five order of magnitude difference. "Clearing the orbit" isn't precisely defined... and it doesn't need to be. You don't need a precise definition of where exactly on the beach the ocean begins to know that Asia and North America are separated by the Pacific Ocean.
And I suspect that such a large distinction isn't a cosmic accident, and that other star systems of sufficient age will show a similar trend. Unfortunately it's going to be a long time before we can test this hypothesis.
The sun will become a white dwarf, which is a post-stellar remnant made of electron-degenerate matter (where the electromagnetic repulsion is not sufficient to hold electrons apart against gravity, and instead they're held apart by the Pauli Exclusion Principle) about the size of the earth. Before that, when it ends its Red Giant phase, it will shed much of its mass in novas. Which are gentle events only in comparison to a supernova. "Explosion" is quite fair. Certainly nobody in the solar system watching would say, Crocodile Dundee style, "That's not an explosion..."
The most difficult math course I ever took was my first college math course, Calc II with Maple. Why yes, use of the symbolic calculus program Maple was so important to the class it was in the name. We took our tests at a workstation with Maple on it.
When my adviser suggested I take this version instead of normal Calc II, I didn't hesitate because I naively assumed this would make the class easier.
Turns out that when you remove the time it takes to do the actual mechanics of taking integrals and derivatives, you can instead focus on problems where the difficulty is figuring out how to set up that integral and derivative. Which is much harder than following some rules by rote.
That's why Feynman Diagrams were such a big deal -- they actually allowed physicists to figure out how they should be applying the equations of quantum mechanics to a specific problem. It let them figure out what to calculate. How wasn't the challenge.
I don't know, exactly. I'm assuming it's the same Aristotlean Physics Kook from quite some time ago with a new nick. They had a pretty extensive blog about how Newtonian mechanics was wrong and Aristotlean motion was obviously correct. Seemed like a bit much for just a troll. So, instead, I think it's your run of the mill Internet Crackpot who never studied any physics, came across one puzzling question, decided ignorance + a question + their genius = proving everyone else wrong. The rest is history and irrational slashdot posts.
I am so tired of the 'Mankind's existence is valueless' bravado. We are a billion to one galactic coincidence that has risen to sentient thought and self-awareness.
Well I don't know about how big a coincidence we are, but so what. There might be a trillion sentient species in our galaxy, but so what. None of them are us. Just like there are billions of humans out there besides myself, but none of them are me. "Humanity will still exist" isn't an acceptable excuse for me to neglect my own survival, and "Sentient life forms will still exist" wouldn't be an acceptable excuse to let our species die out.
Bravado, such a perfect word for this. Funny how this kind of bravado is the opposite of the bravery to go on existing. We didn't get here by not wanting to survive.
Bwa ha ha! So glad to know I nailed it the first time. But wait, there is in fact a nuance here that I missed. It's not that they're wasting their time actually doing the research -- even though, you know, that's exactly what you said -- because obviously nobody should give a shit what you think is important to research or not. Obviously.
No, it's that they just shouldn't bother releasing their research until they've converted it into something you think is important.
And of course you think that's not ridiculous.
Since you're a Tardino emitter of intensity equal to the Large Moron Colider, let me explain: Releasing their research is how they make others aware of and interested in their findings, eventually enabling one of them to be the ones who discovers how to turn this into something you'd care about. Science is colaborative, you see, and you never know which other scientist might be the one to make the breakthrough; it might not even be someone who has their degree yet, and is only reading about this on /.. Notice how this is basically the same thing I already said? No matter. Now that I understand your point better, though, I think I can cut down to what you really meant.
You didn't really mean that it's a waste of time to do the research, or publish the research. You said those things, but that's obviously not what you meant.
What you really meant is that they're wasting their time telling you.
Which is also obvious. But not their problem. Don't click the link if you're not interested in things that won't go into your iPhone, you incurious clod.
What didn't I understand? It's a pretty simple point. Research of things occurring on a time frame of billions of years is useless, research of things that will show results in a few decades isn't.
Right? That's almost exactly what you wrote.
And since if you understood that researching things that'll happen billions of years from now could result in unexpected discoveries relevant on the shorter timescale you approve of, but that you don't know this when you begin researching, you never would have written something so stupid, I think I get the point quite well.
Feel free to elaborate. I'm sure there's a deep nuance to your point that I'm missing.
Oh God, not this Aristotlean nonsense again. Nothing keeps or is needed to keep an object in motion. Something (as in a transfer of momentum and energy) is what you need to make an object stop.
It is certainly true that you are not equally clueless as physicists.