5 ms·

Discovered in 1998, and explained in 2008 using generally accepted equations, at http://finbot.wordpress.com/2008/03/05/dark-energy-obviated/ http://finbot.word

Discovered in 1998, and explained in 2008 using generally accepted equations, at http://finbot.wordpress.com/2008/03/05/dark-energy-obviated/ http://finbot.wordpress.com/2008/03/05/dark-energy-obviated/ In short, if you launch a unpowered projectile upward at close to the speed of light, Einstein's prediction of gravitational time dilation (experimentally confirmed) in turn predicts that the projectile accelerates away from you, for as long as its velocity relative to you is close to the speed of light. (The ivory tower no longer considers ideas that source outside the tower, which explains why this idea is in a blog.)

dTal 13y ago
I can't pretend to understand relativity well enough to verify that blog post's maths, but one of the notes caught my eye: <quote> 2. Herein, as in most relativity texts, we ignore the travel time of light that prevents a remote event from being seen until after it has occurred. In principle a network of observers can be set up in locally inertial frames that momentarily co-move with the rocket, so that events can be detected by equipment right next to them, and the records subsequently compiled and analyzed. </quote> I could be reading that wrong, but the author seems to be suggesting that time's inherent inconsistency at relativistic speeds and distances can be mitigated with a "network of observers". I don't know if that's true, but "momentarily co-move with the rocket" sounds like it's ignoring an awful lot of relativistic acceleration of the measuring devices.
- fargolime 13y ago
  The network of observers are moving inertially (i.e. unpowered, freely falling), moving with the rocket for only a moment, so they're not accelerating like the rocket is. That's how those observers can make good measurements, in that moment. For more info search for "momentarily comoving inertial frame" at http://math.ucr.edu/home/baez/physics/Relativity/SR/clock.html http://math.ucr.edu/home/baez/physics/Relativity/SR/clock.ht.... Each inertial clock can measure the passage of time accurately.
pdonis 13y ago
The math in this post is fine (since, as you note, it's just plugging in numbers to "generally accepted equations"), but it is "solving" the wrong problem: if you launch a unpowered projectile upward at close to the speed of light, Einstein's prediction of gravitational time dilation (experimentally confirmed) in turn predicts that the projectile accelerates away from you In other words, the "acceleration profile" produced by this model is: acceleration, then deceleration. But the "acceleration profile" that needs to be explained for our actual universe is deceleration, then acceleration: an apparent slowing down of the universe's expansion, followed by an apparent speeding up. There's no way to get that out of the blog post's model.
- fargolime 13y ago
  To be novel the blog need only show one thing that isn't currently known. Generally accepted physics doesn't recognize that an unpowered projectile launched upward can accelerate away, let alone shown with generally accepted equations. The blog is novel for that alone. The blog explains the acceleration away of supernovae that is currently a mystery, so the blog is novel again for that reason. If we don't accept an advance of physics until it explains a complete set of mysteries (an acceleration profile over the universe's history, in your case), we could be waiting a long time. The "deceleration, then acceleration" is an implication based on assumptions, not something observed. We haven't actually witnessed any deceleration or acceleration when looking through a telescope. Instead, when we look at various distances from the Earth we see various redshifts (not changes in redshifts), and then, because looking further away is looking back further in the history of the universe (a safe assumption), and based on the assumption that space itself is expanding to cause those redshifts and any changes in those redshifts, we conclude that space itself expanded in a decelerating manner and then, later in the universe's history, in an accelerating manner. The blog implies that we should rethink those assumptions. It shows that the expanding space paradigm is superfluous. When that paradigm is removed, generally accepted equations can be applied to show that objects sufficiently far away from us (which we can now assume are receding at close to the speed of light, given their high redshifts) accelerate away from us. So when we look close to us we'll see evidence of deceleration, and when we look further from us we'll see evidence of acceleration, but that has nothing to do per se with the history of the universe. Thus the blog does explain the observations that form the acceleration profile you note.

dTal 13y ago

I can't pretend to understand relativity well enough to verify that blog post's maths, but one of the notes caught my eye: <quote> 2. Herein, as in most relativity texts, we ignore the travel time of light that prevents a remote event from being seen until after it has occurred. In principle a network of observers can be set up in locally inertial frames that momentarily co-move with the rocket, so that events can be detected by equipment right next to them, and the records subsequently compiled and analyzed. </quote> I could be reading that wrong, but the author seems to be suggesting that time's inherent inconsistency at relativistic speeds and distances can be mitigated with a "network of observers". I don't know if that's true, but "momentarily co-move with the rocket" sounds like it's ignoring an awful lot of relativistic acceleration of the measuring devices.

fargolime 13y ago
The network of observers are moving inertially (i.e. unpowered, freely falling), moving with the rocket for only a moment, so they're not accelerating like the rocket is. That's how those observers can make good measurements, in that moment. For more info search for "momentarily comoving inertial frame" at http://math.ucr.edu/home/baez/physics/Relativity/SR/clock.html http://math.ucr.edu/home/baez/physics/Relativity/SR/clock.ht.... Each inertial clock can measure the passage of time accurately.

pdonis 13y ago

The math in this post is fine (since, as you note, it's just plugging in numbers to "generally accepted equations"), but it is "solving" the wrong problem: if you launch a unpowered projectile upward at close to the speed of light, Einstein's prediction of gravitational time dilation (experimentally confirmed) in turn predicts that the projectile accelerates away from you In other words, the "acceleration profile" produced by this model is: acceleration, then deceleration. But the "acceleration profile" that needs to be explained for our actual universe is deceleration, then acceleration: an apparent slowing down of the universe's expansion, followed by an apparent speeding up. There's no way to get that out of the blog post's model.

fargolime 13y ago
To be novel the blog need only show one thing that isn't currently known. Generally accepted physics doesn't recognize that an unpowered projectile launched upward can accelerate away, let alone shown with generally accepted equations. The blog is novel for that alone. The blog explains the acceleration away of supernovae that is currently a mystery, so the blog is novel again for that reason. If we don't accept an advance of physics until it explains a complete set of mysteries (an acceleration profile over the universe's history, in your case), we could be waiting a long time. The "deceleration, then acceleration" is an implication based on assumptions, not something observed. We haven't actually witnessed any deceleration or acceleration when looking through a telescope. Instead, when we look at various distances from the Earth we see various redshifts (not changes in redshifts), and then, because looking further away is looking back further in the history of the universe (a safe assumption), and based on the assumption that space itself is expanding to cause those redshifts and any changes in those redshifts, we conclude that space itself expanded in a decelerating manner and then, later in the universe's history, in an accelerating manner. The blog implies that we should rethink those assumptions. It shows that the expanding space paradigm is superfluous. When that paradigm is removed, generally accepted equations can be applied to show that objects sufficiently far away from us (which we can now assume are receding at close to the speed of light, given their high redshifts) accelerate away from us. So when we look close to us we'll see evidence of deceleration, and when we look further from us we'll see evidence of acceleration, but that has nothing to do per se with the history of the universe. Thus the blog does explain the observations that form the acceleration profile you note.