What depresses me the most, as a high school physics teacher, is how right you are. Too often I see a lack of desire to actually think about things, rather than rely on the data.
I want to scream at some points when the students are doing labs/I'm grading their labs.
"Data is king! It determines truth. If it doesn't match with what you expected, one of two things is going on. Either your expectations were wrong or you didn't do a good enough experiment."
You'd be surprised (or maybe not, this is Slashdot...) how many students think "I did the experiment once, my data is perfect, nothing could have possibly gone wrong." If they would shut up from talking about how their weekend went and actually think about what they're doing it would all be so much easier.
Ok, I've gone off topic. My apologies. But seriously, stop, examine data and where it came from. Don't go by who told it to you, go by what was told.
Stop. Please. Just stop. You're making real physicists cry.
It is NOT science when one makes up theories that have no basis in actual repeated observation or experiment. Einstein's theories have many aspects. Some of these aspects have been experimentally verified to many decimal places of accuracy. Others, such has some of his ideas about gravity have not, at least as far as I know. He did not like quantum science all that much, until experimental evidence piled up. Questioning Einstein is akin to heresy in religion, but I am under the impression that science is different, that it is based on observation and experiments. Maybe I am wrong about that.
You're allowed to question Einstein. But do it correctly. You can't say "Well, this observation confirms this part of his theory so I'll believe that, but you have no evidence I should believe a different part of the same theory." It doesn't work like that. If one part is shown to be consistent with data then that says that there may very well be something behind the other parts. They're all part and parcel. Science does not accept a line-item veto. If one properly constructed conclusion is disproven then the whole theory is called into question. And so, saying that several pieces of Einstein's theory have been shown accurate to umpteen decimal places lends a hell of a lot of credibility to the rest. They're all part of the same theory.
Consider 2 points that according to general relativity, have a variable distance between them, when it varies, doesn't the frequency of light between these vary as well ? doesn't the detector of light vary as well ? if all content varies uniformly, how could there be any "detection" at all unless something broke the rule of spacetime bending ? do the nuclear forces feel the need to have their own definition of length that doesn't change ?
I wrestled with this one too. After a little bit of research I think I have an answer for you. Yes, the distances would change and the frequency would change but the speed of light through the distance would not. Which would lead to it taking a shorter/longer amount of time for the light to travel the distance between the two masses. If I recall correctly that is the underlying basis for relativity. If you look at the LIGO fact sheet from the group doing this work they use this difference in time to look for phase changes in two originally in phase light rays.
Many are able to see the potential of interpreting gravity as the product of observing the universe changing shape. Time could very well be the product of a high degree of causality and stability in a changeable universe and not a dimension at all.
Sounds intriguing. Please elaborate as I haven't heard of this one.
I'm confused by your point about the debate on the definition of force. I've never heard that one. Can you point me to some references? Everything I've seen shows it as just the negative derivative of potential energy.
Ok, now you've just plain confused me. Where did I ever suggest the relativity was wrong? When did I ever say math is bad? It seems to me that's what I've been advocating the entire discussion here. What I'm arguing with is your dismissal of the very definitions of force and energy.
Now, the quantifiable formulas for each of these forces and energies are up for grabs as new relationships and new laws are formulated. But the definition of a force and the definition of energy are not. I was taking offense to your dismissal of gravity as 'not really a force' (you said something to that effect) and gravitational waves as not being energy bearing (also said by you), and the fact that your dismissal of these ideas through the use of some metaphysical argument.
But, unless I'm misunderstanding what a gravity wave is there is no motion in the direction perpendicular to propagation. It's a stretch/squeeze (ok, stretch/more stretch) thing as space warps differently. If I'm looking at it right the wikipedia illustration is off as the circle warps not just in and out but up and down. I don't see why it should do that.
Of course I believe in causality. To an extent. You only have to look at simple beginner's quantum mechanics to know something ain't right. Oh, and please don't go to the hidden variable idea. It's been debunked rather well. You're straying from my argument. Again, you fall back on quotes and flowery prose.
The point of it all is that all of this falls back onto the mathematics used to describe reality. Abstract concepts like energy and force (especially field forces like gravity) can't be described properly using words. They need hard quantifiable numbers.
Go take a couple of courses in Relativistic physics. And throw in a good Calculus course or four. Then maybe come back and try again.
mumble mumble hippies mumble mumble
"So, I have a real problem with gravity waves imparting energy at all - these waves are an illusion of spacetime bending, not some force that is exerted. From a philosphical point of view, gravity is not a force, it is merely a product of observing a universe changing shape, from within the universe of course."
I'm sorry, you're not allowed to "have a problem" with it unless you can show the error in the math. Relativity is not Einstein just practicing an "application of philosophic principles to physics." There's a reason he took a long time to go from Special Relativity to General Relativity. He had to go learn the math from Minkowski (I'm simplifying their relationship a bit). You can't do it correctly without the math. You can talk about it but once you hit abstract concepts like "Energy" you need to go to the math. You're not allowed to "have a problem" with a moving object having kinetic energy. That math defines it as so. Same thing in the gravity case.
I've said it before in this thread and I'll say it again. Go read a text book, then come back and talk to me.
Seriously, what history books have you been reading? You've got parts right. Gravity is indistinguishable from acceleration if you attempt to treat an accelerating body as an inertial reference frame. Yes, an imaginary force does appear if you do the coordinate substitution in this case (see any number of textbook, or, if you enjoy comedy this).
But to assert that the gravitational portions of relativity have never been shown experimentally is ignoring history. I point you towards the precession of Mercury's orbit and the first observation of gravitational lensing in 1919 (See the Story of Eddington and the Eclipse, laid out in many places and quite humorously here. And that's just the simple ones. It's called General Relativity.
Now, let's look at some of your errors here:
1)"Two neutron stars or black holes in close proximity, could have way more influence on each other and the radiation emitted, by way of the electric interactions between them, than by gravity."
Ok, true, given certain things. Even true about the radiation. Except for we're not talking about EM radiation in this context, we're talking about gravitational radiation, which shows no response to EM forces.
2)"Newtonian mechanics mandate that gravity ITSELF not be in any way be impacted by time. Only the ACCELERATION produced by gravity has a time value. Since the planets and galaxies don't move relative to each other at anywhere close to the speed of light, relativity doesn't enter into the picture here."
I'm not even sure where to begin here. Newton is wrong. Sorry to say it. I teach his laws every day in class, and he's wrong. He got damn close but his basic assumptions about the nature of reality are off. Space and time are not static. The force of gravity is only varies with time as the location and the mass creating the space-time curving effect that we see as gravity varies. So, if the object moves (like, oh, I don't know, a binary black hole system) the force we notice will vary. It takes time for the information that the force has changed to reach us. We don't notice instantly. That would mean information has traveled faster than light. Which is not possible.
Oh, and by the way, relativity does enter into this as General Relativity is a description of gravity.
Seriously, go read the first couple of sections ofThe Elegant Universe. And then go read a text book.
Maybe I'm still stuck in picturing things in three dimensions but I can't see how you could possibly create a transverse gravitational wave. From what I understand a gravitational wave is a distortion in the warp in space time due to a massive object oscillating toward and away from you. This would result in a space-time that, as the wave hits, is alternating between flat/curved (or as LIGO would see it unstretched/stretched) (ok, curved and more curved for all you sticklers out there). This seems to me to be the definition of a longitudinal wave (ex definition). Whereas a transverse wave would require flexing perpendicular to the axis LIGO is looking at and therefore unmeasurable. I may be completely off my rocker, but I do know the definitions of transverse and longitudinal. (At least I hope I do. If not, I've been teaching my high school students incorrectly with the awesomely long slinky)
Looking forward to seeing where I'm wrong or right. Thanks.
Newtonian gravitational equations. In that you are correct. But reality is Non-Newtonian. All Jupiter knows is what the Sun was doing 43 minutes ago. All we know is what the Sun was like 8 minutes ago. Relativity puts a speed limit not just on light but on any type of information transfer. Unless you want to throw out causality. Go read your Einstein again. Or even any introductory physics text on relativity. They explain it quite well. Or here, for anyone who likes small words, try this.
The General Theory of Relativity says they should move at the speed of light. They are simply warps in space-time that are caused events involving really big masses (like black holes colliding). They are basically changes in gravitational forces as very massive object move. A classical example is two black holes rotate around each other and approach and collide. The gravitational forces vibrate up and down in magnitude as the objects move towards and away from us. That is the wave we're trying to detect.
You know, you've made a good point, and the way I put it makes me sound like an idiot. Serves me right for trying to slip a comment in while at work and not get caught.
"Beware of altruism. It is based on self-deception, the root of all evil." -- Lazarus Long
I guess he was right, just not in the way he intended. We're deceiving ourselves by imagining we're doing it out of the goodness of our hearts, when it's actually because we're forced to like it.
I'm sorry, but everyone who tries to make an absolute declaration of "taking notes helps more" versus "just listening and getting printouts of notes helps more" is missing the major point. This is something I encounter far too often as a high school teacher. There is no one perfect way to do it. There are different styles of learning depending on who you are. Some people are auditory learners and some are visual and some are kinesthetic (they learn by doing). Personally, I'm kinesthetic and visual, so when I was in high school, I learned best by taking notes. Some of my students are auditory, they listen, and then take the notes at a later date, when they can concentrate on what they're writing. Please don't try to set absolutes, as you're going against educational research (sorry, I don't have citations at my beck and call, I'm in the middle of a prep period during the teaching day, so I only have a few minutes to myself before kids come in for class)
I think I would want to know what those eight degrees are before signing up. I mean, if they're all the normal articulation points, plus rotations and open/closing the hand, cool. If maybe two are motion and the rest are crap like the freedom of speech, the freedom of the press and so on...well, I don't want to give an opening for these to go from Robot-arm servants to Robot-arm overlords. And letting our arms get their fair say in the media is only the first step...
These sound interesting, but I have to wonder, if if they're released, where in the world will they be viewable? I mean, it's great that these are getting made, but pretty useless IMHO if the only place to see them is at some film festival that is inaccessible to the everyday person.
I read TFA, maybe I missed it. The question I want answered is whether they can harvest these cells once and grow them to use them many times. You can do that with stem cells. Curious if it works that way here. It seems that way but I'm not sure.
You also have to wonder about type matches. Maybe it's an incorrect analogy, but blood and organ transfusions need to be matched by type. Is the same true here? I wouldn't be surprised if it was.
Just some food for thought in a more serious vein.
Personally, I would love to work in a relatively Faraday caged building. Heck, they could even just cage individual rooms. As a high school physics teacher it really gets annoying when the students are so addicted to their cell phones that they check for text messages every five minutes.
I may even think about doing it myself, how much would 1500 square feet of wire mech cost....The whole key is that the mesh around the building/room is continuous at the edges.
Slashdot Mirror
I want to scream at some points when the students are doing labs/I'm grading their labs.
"Data is king! It determines truth. If it doesn't match with what you expected, one of two things is going on. Either your expectations were wrong or you didn't do a good enough experiment."
You'd be surprised (or maybe not, this is Slashdot...) how many students think "I did the experiment once, my data is perfect, nothing could have possibly gone wrong." If they would shut up from talking about how their weekend went and actually think about what they're doing it would all be so much easier.
Ok, I've gone off topic. My apologies. But seriously, stop, examine data and where it came from. Don't go by who told it to you, go by what was told.
Stop. Please. Just stop. You're making real physicists cry.
It is NOT science when one makes up theories that have no basis in actual repeated observation or experiment. Einstein's theories have many aspects. Some of these aspects have been experimentally verified to many decimal places of accuracy. Others, such has some of his ideas about gravity have not, at least as far as I know. He did not like quantum science all that much, until experimental evidence piled up. Questioning Einstein is akin to heresy in religion, but I am under the impression that science is different, that it is based on observation and experiments. Maybe I am wrong about that.
You're allowed to question Einstein. But do it correctly. You can't say "Well, this observation confirms this part of his theory so I'll believe that, but you have no evidence I should believe a different part of the same theory." It doesn't work like that. If one part is shown to be consistent with data then that says that there may very well be something behind the other parts. They're all part and parcel. Science does not accept a line-item veto. If one properly constructed conclusion is disproven then the whole theory is called into question. And so, saying that several pieces of Einstein's theory have been shown accurate to umpteen decimal places lends a hell of a lot of credibility to the rest. They're all part of the same theory.
Consider 2 points that according to general relativity, have a variable distance between them, when it varies, doesn't the frequency of light between these vary as well ? doesn't the detector of light vary as well ? if all content varies uniformly, how could there be any "detection" at all unless something broke the rule of spacetime bending ? do the nuclear forces feel the need to have their own definition of length that doesn't change ?
I wrestled with this one too. After a little bit of research I think I have an answer for you. Yes, the distances would change and the frequency would change but the speed of light through the distance would not. Which would lead to it taking a shorter/longer amount of time for the light to travel the distance between the two masses. If I recall correctly that is the underlying basis for relativity. If you look at the LIGO fact sheet from the group doing this work they use this difference in time to look for phase changes in two originally in phase light rays.
Many are able to see the potential of interpreting gravity as the product of observing the universe changing shape. Time could very well be the product of a high degree of causality and stability in a changeable universe and not a dimension at all. Sounds intriguing. Please elaborate as I haven't heard of this one.
I'm confused by your point about the debate on the definition of force. I've never heard that one. Can you point me to some references? Everything I've seen shows it as just the negative derivative of potential energy.
Ok, now you've just plain confused me. Where did I ever suggest the relativity was wrong? When did I ever say math is bad? It seems to me that's what I've been advocating the entire discussion here. What I'm arguing with is your dismissal of the very definitions of force and energy.
Now, the quantifiable formulas for each of these forces and energies are up for grabs as new relationships and new laws are formulated. But the definition of a force and the definition of energy are not. I was taking offense to your dismissal of gravity as 'not really a force' (you said something to that effect) and gravitational waves as not being energy bearing (also said by you), and the fact that your dismissal of these ideas through the use of some metaphysical argument.
But, unless I'm misunderstanding what a gravity wave is there is no motion in the direction perpendicular to propagation. It's a stretch/squeeze (ok, stretch/more stretch) thing as space warps differently. If I'm looking at it right the wikipedia illustration is off as the circle warps not just in and out but up and down. I don't see why it should do that.
Of course I believe in causality. To an extent. You only have to look at simple beginner's quantum mechanics to know something ain't right. Oh, and please don't go to the hidden variable idea. It's been debunked rather well. You're straying from my argument. Again, you fall back on quotes and flowery prose.
The point of it all is that all of this falls back onto the mathematics used to describe reality. Abstract concepts like energy and force (especially field forces like gravity) can't be described properly using words. They need hard quantifiable numbers. Go take a couple of courses in Relativistic physics. And throw in a good Calculus course or four. Then maybe come back and try again. mumble mumble hippies mumble mumble
"So, I have a real problem with gravity waves imparting energy at all - these waves are an illusion of spacetime bending, not some force that is exerted. From a philosphical point of view, gravity is not a force, it is merely a product of observing a universe changing shape, from within the universe of course."
I'm sorry, you're not allowed to "have a problem" with it unless you can show the error in the math. Relativity is not Einstein just practicing an "application of philosophic principles to physics." There's a reason he took a long time to go from Special Relativity to General Relativity. He had to go learn the math from Minkowski (I'm simplifying their relationship a bit). You can't do it correctly without the math. You can talk about it but once you hit abstract concepts like "Energy" you need to go to the math. You're not allowed to "have a problem" with a moving object having kinetic energy. That math defines it as so. Same thing in the gravity case.
I've said it before in this thread and I'll say it again. Go read a text book, then come back and talk to me.
Seriously, what history books have you been reading? You've got parts right. Gravity is indistinguishable from acceleration if you attempt to treat an accelerating body as an inertial reference frame. Yes, an imaginary force does appear if you do the coordinate substitution in this case (see any number of textbook, or, if you enjoy comedy this).
But to assert that the gravitational portions of relativity have never been shown experimentally is ignoring history. I point you towards the precession of Mercury's orbit and the first observation of gravitational lensing in 1919 (See the Story of Eddington and the Eclipse, laid out in many places and quite humorously here. And that's just the simple ones. It's called General Relativity.
Now, let's look at some of your errors here:
1)"Two neutron stars or black holes in close proximity, could have way more influence on each other and the radiation emitted, by way of the electric interactions between them, than by gravity."
Ok, true, given certain things. Even true about the radiation. Except for we're not talking about EM radiation in this context, we're talking about gravitational radiation, which shows no response to EM forces.
2)"Newtonian mechanics mandate that gravity ITSELF not be in any way be impacted by time. Only the ACCELERATION produced by gravity has a time value. Since the planets and galaxies don't move relative to each other at anywhere close to the speed of light, relativity doesn't enter into the picture here."
I'm not even sure where to begin here. Newton is wrong. Sorry to say it. I teach his laws every day in class, and he's wrong. He got damn close but his basic assumptions about the nature of reality are off. Space and time are not static. The force of gravity is only varies with time as the location and the mass creating the space-time curving effect that we see as gravity varies. So, if the object moves (like, oh, I don't know, a binary black hole system) the force we notice will vary. It takes time for the information that the force has changed to reach us. We don't notice instantly. That would mean information has traveled faster than light. Which is not possible.
Oh, and by the way, relativity does enter into this as General Relativity is a description of gravity.
Seriously, go read the first couple of sections ofThe Elegant Universe. And then go read a text book.
Maybe I'm still stuck in picturing things in three dimensions but I can't see how you could possibly create a transverse gravitational wave. From what I understand a gravitational wave is a distortion in the warp in space time due to a massive object oscillating toward and away from you. This would result in a space-time that, as the wave hits, is alternating between flat/curved (or as LIGO would see it unstretched/stretched) (ok, curved and more curved for all you sticklers out there). This seems to me to be the definition of a longitudinal wave (ex definition). Whereas a transverse wave would require flexing perpendicular to the axis LIGO is looking at and therefore unmeasurable. I may be completely off my rocker, but I do know the definitions of transverse and longitudinal. (At least I hope I do. If not, I've been teaching my high school students incorrectly with the awesomely long slinky)
Looking forward to seeing where I'm wrong or right. Thanks.
Newtonian gravitational equations. In that you are correct. But reality is Non-Newtonian. All Jupiter knows is what the Sun was doing 43 minutes ago. All we know is what the Sun was like 8 minutes ago. Relativity puts a speed limit not just on light but on any type of information transfer. Unless you want to throw out causality. Go read your Einstein again. Or even any introductory physics text on relativity. They explain it quite well. Or here, for anyone who likes small words, try this.
The General Theory of Relativity says they should move at the speed of light. They are simply warps in space-time that are caused events involving really big masses (like black holes colliding). They are basically changes in gravitational forces as very massive object move. A classical example is two black holes rotate around each other and approach and collide. The gravitational forces vibrate up and down in magnitude as the objects move towards and away from us. That is the wave we're trying to detect.
If I recall my Astronomy they have to know the trajectory of the orbit very precisely before naming the rock.
You know, you've made a good point, and the way I put it makes me sound like an idiot. Serves me right for trying to slip a comment in while at work and not get caught.
"Beware of altruism. It is based on self-deception, the root of all evil." -- Lazarus Long I guess he was right, just not in the way he intended. We're deceiving ourselves by imagining we're doing it out of the goodness of our hearts, when it's actually because we're forced to like it.
I'm sorry, but everyone who tries to make an absolute declaration of "taking notes helps more" versus "just listening and getting printouts of notes helps more" is missing the major point. This is something I encounter far too often as a high school teacher. There is no one perfect way to do it. There are different styles of learning depending on who you are. Some people are auditory learners and some are visual and some are kinesthetic (they learn by doing). Personally, I'm kinesthetic and visual, so when I was in high school, I learned best by taking notes. Some of my students are auditory, they listen, and then take the notes at a later date, when they can concentrate on what they're writing. Please don't try to set absolutes, as you're going against educational research (sorry, I don't have citations at my beck and call, I'm in the middle of a prep period during the teaching day, so I only have a few minutes to myself before kids come in for class)
I think I would want to know what those eight degrees are before signing up. I mean, if they're all the normal articulation points, plus rotations and open/closing the hand, cool. If maybe two are motion and the rest are crap like the freedom of speech, the freedom of the press and so on...well, I don't want to give an opening for these to go from Robot-arm servants to Robot-arm overlords. And letting our arms get their fair say in the media is only the first step...
These sound interesting, but I have to wonder, if if they're released, where in the world will they be viewable? I mean, it's great that these are getting made, but pretty useless IMHO if the only place to see them is at some film festival that is inaccessible to the everyday person.
I read TFA, maybe I missed it. The question I want answered is whether they can harvest these cells once and grow them to use them many times. You can do that with stem cells. Curious if it works that way here. It seems that way but I'm not sure.
You also have to wonder about type matches. Maybe it's an incorrect analogy, but blood and organ transfusions need to be matched by type. Is the same true here? I wouldn't be surprised if it was.
Just some food for thought in a more serious vein.
I may even think about doing it myself, how much would 1500 square feet of wire mech cost....The whole key is that the mesh around the building/room is continuous at the edges.