Perhaps because 1080p can have varying horizontal resolution (1920, 1440, possibly others), whereas now 4K has a fixed horizontal resolution, it's better marketing to use the bigger number.
but they never seem to get to the next stage of the paradox, which is, from the "travelling" twin's point of view, he is the one that is stationary and the other twin is the one that is moving.
In the "classic" twin paradox only one twin undergoes acceleration (at at least three points his journey - launch, turn-around and return), which is what breaks the symmetry between them.
Ah , but absorbtion and re-emission isn't an instantanious process
There may be a finite time between the two but why can't the individual events themselves be instantaneous?
Photons don't go slower in a medium because they're being continuously absorbed and emitted - or so I heard. It's something like: in a medium the wavefunctions of travelling light wind up interfering with each other in such a way as to produce the overall effect of a slower speed through the medium. I got a bit lost during that particular YouTube video, I'll admit.
So, Larry says Ralph aged less, and Ralph says Larry aged less. Both are right. This is the paradox.
But it is just an apparent paradox, isn't it? If Larry and Ralph then turn around and both head back to the station for a space beer, they'll find their clocks are in agreement. If on the other hand only Ralph turns around and catches up with Larry, their differing frames will account for any differences in their clocks once they meet up.
While they're spatially separated simultaneity goes out of the window a bit, doesn't it?
Ah, well, now, there you've got me. Mind you, what interactions does a photon undergo? They get emitted and they get absorbed, but what else can they do?
---
I'm quite pleased to say that after dribbling out the above I did some speculative topic-directed pseudo-random research (Googling) and came across some more ideas in the same vein. Apparently photons really don't do anything except get emitted and get absorbed, and (so I read) between those two events they don't exist.
To the photon, its emission and absorption are the same event (travelling at c, they don't even have a "concept" of spacetime for events to occur in). Mapped into our frame of reference they become different events, but since the only way to detect a photon is to adsorb it (it says here) they are indistinguishable from non-existent while "in flight."
I've already posted, but I would have given you my last mod point. If nothing else, perhaps this reply will bring your post to the attention to someone who can mod it up (and mod me out of sight).
My first thought was "Why not use better quality lenses?" Sure, they'd be more expensive, but there is an expense involved in the software having to correct Every Single Frame. Why not fix it once, at the source, and obviate the need for continuous real-time updates?
Because the corrections are needed no matter how good your lenses are - it's a remapping of pixels so those pixels appear in the correct place in your plane of vision, and doesn't have anything to do with compensating for low quality lenses.
I'd imagine a learning session where certain scenes (e.g. grids) are displayed and the system would apply software corrections under my control until it looked good to me.
Not possible, I'm afraid. Whatever the screen puts out is going to get blurred by your astigmatism and short-sightedness, and only a physical lens can pre-correct it for your eyes.
(the following has turned into far more of a ramble than I first expected. I hope at least some of it makes sense)
But, if you must, it helps me to remember that the only absolute is spacetime. How you divide that up into space and time is dependent on your path through it.
If you were asked to divide a field into a coordinate grid, you might choose an arbitrary direction and then divide it up left-right and forward-backward from there. Someone else might face a different a direction and do the same thing - a different grid, but also a perfectly valid way to divide up the field.
So it is, sort of, with spacetime. But we don't choose our direction - instead it depends on our motion. If you're moving relative to another person, a bit of what they'd call space overlaps with a bit of what you'd call time, just as in the field where a bit of what they might call left-right overlaps with what you call forward-backward. There's a negative sign in the equations somewhere that puts the brakes on things though, and means you can't accelerate to the speed of light relative to anyone else without expending an infinite amount of energy. In Greg Egan's Clockwork Rocket series, the negative sign acts is switched with a positive one, so it's more like the easy-to-imagine field, and by accelerating one can completely swap what your home-bound friend would call time for a spatial dimension. Once they have accelerated enough, the travelling explorers can continue to experience time while none at all passes on their home planet. I think the implication is that by accelerating yet further, one could easily travel back in time. In fact, the danger in the story is from objects - quite possibly another otherwise perfectly ordinary solar system - travelling at right angles to the protagonist's home system - effectively at infinite speed.
The next brain-melting thing to consider is that, perhaps, everything moves at the speed of light - not through space, but through spacetime. But because most of the stuff we're familiar with - the Earth, the stars, etc - shares roughly the same path through spacetime, we don't experience it like that. All of our speed is taken up with travel into the future. We could swap a bit of it for travel through space if we accelerate. Without relativity, you could expect to travel for ten years there-and-back-again and find that ten years have passed at home. If you consider the simple field "swap" situation, you might conclude that by swapping some of your travel through time for travel through space, you'd find yourself less far into the future when you got back. But then that niggly negative sign comes into play - it makes me think of time as sort of 1/space - which means you actually find yourself more far into the future when you get back. Hence the twin paradox, where you find your Earth-bound friends have aged more than you have.
In the case of the photon, which uses up all of it's speed travelling through space, no time ever passes for it.
Any questions? No? Good. I'm off to catch up on the few hours of sleep I missed last night. Does it show?
Can we please get a reasonabley priced laptop with more than 1366x768 resolution.
If by "reasonably priced" you mean "for the same price as a 1366x768 laptop" then no, of course not. More pixels cost more. They are also not what your average user is bothered about, so manufacturers won't waste money by putting high-res screens on otherwise budget laptops.
To consider the efficiency of that system you must consider the efficiency of all stages combined, and the lower efficiencies (the weak links in the chain) of that system will be upsteam, at the power station and in the transmission of that electricity to the car batteries, including through the "manhole covers".
And exactly the same goes for the transport of fossil fuels, doesn't it? It doesn't get from under the ground to the gas station for free.
if the power station burns fossil fuels the efficiency of the whole system will be lower than that of an internal combustion engine car.
Emphasis mine, in order to ask: why must this be true?
In fact, I'm not exactly sure what you're comparing here. Are you saying the efficiency of the whole (power station-electricity grid-electric car) system will be lower than that of just the ICE car? Or lower than that of the whole (oil platform-transport system-gas station-ICE car) system?
I am shocked at how low this 60% is. An electric motor should be around 90% efficient,and the gear train (if needed) better than 95%, so total ~85%. What are they doing with the rest - are the batteries that lousy?
But it's still far more efficient than petrol, isn't it? I assume that what they're doing with at least some of the rest is powering all the other things a modern car needs to do - just as you would have to burn petrol for in a regular car (minus having to keep the engine ticking over in idle).
But as I said, even if it were 100% the total system efficiency remains low.
Lower than the current system? Or not?
Ditto for heavier industrial stuff (I'm a power station engineer remember)
I trust myself to plug in and use household appliances. I wouldn't trust a succession of random members of the public to use my charging installation without expecting them to break it in several unexpected and expensive ways.
"From the grid" is the key flaw in your argument. In the electricity production line there are similar losses upstream before it even gets to the power outlet.
It's not really my argument, but doesn't the same go for fuel? You need to burn it to transport it, after all.
In fact, if only 60% of the electricity taken by the car reaches the wheel, that is disgracefully inefficient
But still far better than petrol.
no doubt much of it due to the poor air connection between "manhole cover" and car.
The quote I took is only about electric cars in general, so I suspect the losses it's talking about are nothing to do with induction, and presumably more to do with powering the lights, the AC, the power steering, the DVD player, and the dashboard waffle iron.
Personally, I don't get this obsession with avoiding the need to plug in a charging lead. People have managed for years with fuel pumps.
If there was any way to do away with the physical connection, it would be done, but that's always been impossible when your fuel only came in material form. Now, for a 10% increase in efficiency I'd happily plug in, but then the installers of these systems will also have to deal with the extra maintenance (and possibilities for quick and easy abuse) that's always inherent in anything with moving/connecting parts.
Slashdot Mirror
Eh? Whut?
I remember when this was aaallllll orange groves.
While offering some advantages over 3D (no need for specs
My car offers some advantages over my wristwatch. I don't have to lug it around strapped to my arm all day.
Perhaps because 1080p can have varying horizontal resolution (1920, 1440, possibly others), whereas now 4K has a fixed horizontal resolution, it's better marketing to use the bigger number.
Because SEC has the political mission to portray the stock market as a rational
Bzzt.
but they never seem to get to the next stage of the paradox, which is, from the "travelling" twin's point of view, he is the one that is stationary and the other twin is the one that is moving.
In the "classic" twin paradox only one twin undergoes acceleration (at at least three points his journey - launch, turn-around and return), which is what breaks the symmetry between them.
...and Slashdot can't show them to us.
Ah , but absorbtion and re-emission isn't an instantanious process
There may be a finite time between the two but why can't the individual events themselves be instantaneous?
Photons don't go slower in a medium because they're being continuously absorbed and emitted - or so I heard. It's something like: in a medium the wavefunctions of travelling light wind up interfering with each other in such a way as to produce the overall effect of a slower speed through the medium. I got a bit lost during that particular YouTube video, I'll admit.
Apparentle the muni broadband providers don't subscribe to this
Yeah, but they can't guarantee your bits will get through accurately.
Eh... it seems to fall a little flat. Isn't it usually "talk dirty"?
Oh, lighten up. If anything, being only almost correct makes it funnier.
Posting the same story twice in quick succession helps to minimise interference.
So, Larry says Ralph aged less, and Ralph says Larry aged less. Both are right. This is the paradox.
But it is just an apparent paradox, isn't it? If Larry and Ralph then turn around and both head back to the station for a space beer, they'll find their clocks are in agreement. If on the other hand only Ralph turns around and catches up with Larry, their differing frames will account for any differences in their clocks once they meet up.
While they're spatially separated simultaneity goes out of the window a bit, doesn't it?
Nobody wants a Minority Report-style interface.
Ah, well, now, there you've got me. Mind you, what interactions does a photon undergo? They get emitted and they get absorbed, but what else can they do?
---
I'm quite pleased to say that after dribbling out the above I did some speculative topic-directed pseudo-random research (Googling) and came across some more ideas in the same vein. Apparently photons really don't do anything except get emitted and get absorbed, and (so I read) between those two events they don't exist.
To the photon, its emission and absorption are the same event (travelling at c, they don't even have a "concept" of spacetime for events to occur in). Mapped into our frame of reference they become different events, but since the only way to detect a photon is to adsorb it (it says here) they are indistinguishable from non-existent while "in flight."
My melon is now well and truly twisted.
I've already posted, but I would have given you my last mod point. If nothing else, perhaps this reply will bring your post to the attention to someone who can mod it up (and mod me out of sight).
My first thought was "Why not use better quality lenses?" Sure, they'd be more expensive, but there is an expense involved in the software having to correct Every Single Frame. Why not fix it once, at the source, and obviate the need for continuous real-time updates?
Because the corrections are needed no matter how good your lenses are - it's a remapping of pixels so those pixels appear in the correct place in your plane of vision, and doesn't have anything to do with compensating for low quality lenses.
I'd imagine a learning session where certain scenes (e.g. grids) are displayed and the system would apply software corrections under my control until it looked good to me.
Not possible, I'm afraid. Whatever the screen puts out is going to get blurred by your astigmatism and short-sightedness, and only a physical lens can pre-correct it for your eyes.
how can this be, slashdotters?
It just is. Best not to think about it.
(the following has turned into far more of a ramble than I first expected. I hope at least some of it makes sense)
But, if you must, it helps me to remember that the only absolute is spacetime. How you divide that up into space and time is dependent on your path through it.
If you were asked to divide a field into a coordinate grid, you might choose an arbitrary direction and then divide it up left-right and forward-backward from there. Someone else might face a different a direction and do the same thing - a different grid, but also a perfectly valid way to divide up the field.
So it is, sort of, with spacetime. But we don't choose our direction - instead it depends on our motion. If you're moving relative to another person, a bit of what they'd call space overlaps with a bit of what you'd call time, just as in the field where a bit of what they might call left-right overlaps with what you call forward-backward. There's a negative sign in the equations somewhere that puts the brakes on things though, and means you can't accelerate to the speed of light relative to anyone else without expending an infinite amount of energy. In Greg Egan's Clockwork Rocket series, the negative sign acts is switched with a positive one, so it's more like the easy-to-imagine field, and by accelerating one can completely swap what your home-bound friend would call time for a spatial dimension. Once they have accelerated enough, the travelling explorers can continue to experience time while none at all passes on their home planet. I think the implication is that by accelerating yet further, one could easily travel back in time. In fact, the danger in the story is from objects - quite possibly another otherwise perfectly ordinary solar system - travelling at right angles to the protagonist's home system - effectively at infinite speed.
The next brain-melting thing to consider is that, perhaps, everything moves at the speed of light - not through space, but through spacetime. But because most of the stuff we're familiar with - the Earth, the stars, etc - shares roughly the same path through spacetime, we don't experience it like that. All of our speed is taken up with travel into the future. We could swap a bit of it for travel through space if we accelerate. Without relativity, you could expect to travel for ten years there-and-back-again and find that ten years have passed at home. If you consider the simple field "swap" situation, you might conclude that by swapping some of your travel through time for travel through space, you'd find yourself less far into the future when you got back. But then that niggly negative sign comes into play - it makes me think of time as sort of 1/space - which means you actually find yourself more far into the future when you get back. Hence the twin paradox, where you find your Earth-bound friends have aged more than you have.
In the case of the photon, which uses up all of it's speed travelling through space, no time ever passes for it.
Any questions? No? Good. I'm off to catch up on the few hours of sleep I missed last night. Does it show?
Just imagine a banana. Right, now forget that, because it's nothing like a banana.
Can we please get a reasonabley priced laptop with more than 1366x768 resolution.
If by "reasonably priced" you mean "for the same price as a 1366x768 laptop" then no, of course not. More pixels cost more. They are also not what your average user is bothered about, so manufacturers won't waste money by putting high-res screens on otherwise budget laptops.
Life's not fair. Get over it.
which has a 9.7" Retina display
Let me just pass that through my "marketing bullshit" remover:
which has a 9.7" display
To consider the efficiency of that system you must consider the efficiency of all stages combined, and the lower efficiencies (the weak links in the chain) of that system will be upsteam, at the power station and in the transmission of that electricity to the car batteries, including through the "manhole covers".
And exactly the same goes for the transport of fossil fuels, doesn't it? It doesn't get from under the ground to the gas station for free.
if the power station burns fossil fuels the efficiency of the whole system will be lower than that of an internal combustion engine car.
Emphasis mine, in order to ask: why must this be true?
In fact, I'm not exactly sure what you're comparing here. Are you saying the efficiency of the whole (power station-electricity grid-electric car) system will be lower than that of just the ICE car? Or lower than that of the whole (oil platform-transport system-gas station-ICE car) system?
I am shocked at how low this 60% is. An electric motor should be around 90% efficient,and the gear train (if needed) better than 95%, so total ~85%. What are they doing with the rest - are the batteries that lousy?
But it's still far more efficient than petrol, isn't it? I assume that what they're doing with at least some of the rest is powering all the other things a modern car needs to do - just as you would have to burn petrol for in a regular car (minus having to keep the engine ticking over in idle).
But as I said, even if it were 100% the total system efficiency remains low.
Lower than the current system? Or not?
Ditto for heavier industrial stuff (I'm a power station engineer remember)
I trust myself to plug in and use household appliances. I wouldn't trust a succession of random members of the public to use my charging installation without expecting them to break it in several unexpected and expensive ways.
"From the grid" is the key flaw in your argument. In the electricity production line there are similar losses upstream before it even gets to the power outlet.
It's not really my argument, but doesn't the same go for fuel? You need to burn it to transport it, after all.
In fact, if only 60% of the electricity taken by the car reaches the wheel, that is disgracefully inefficient
But still far better than petrol.
no doubt much of it due to the poor air connection between "manhole cover" and car.
The quote I took is only about electric cars in general, so I suspect the losses it's talking about are nothing to do with induction, and presumably more to do with powering the lights, the AC, the power steering, the DVD player, and the dashboard waffle iron.
Personally, I don't get this obsession with avoiding the need to plug in a charging lead. People have managed for years with fuel pumps.
If there was any way to do away with the physical connection, it would be done, but that's always been impossible when your fuel only came in material form. Now, for a 10% increase in efficiency I'd happily plug in, but then the installers of these systems will also have to deal with the extra maintenance (and possibilities for quick and easy abuse) that's always inherent in anything with moving/connecting parts.
Also wireless is always cooler.
No, Kirk would have used it. Picard knows he can pull off the dome.
but I choose to behave as if I have it.
Or so you believe.
Seems to me a room full of philosophers could spend a century mulling over the first question alone.