Yes. Trying to constrain spacetime foam with these photons (see my post way above) is harder than trying to learn something about atoms using your hands (only 10 orders of magnitude or so), and yet over 3 billion years of travel, even little things add up.
So basically, the spacetime foam theory is not playing out?
It's too soon to be sure, but, as the paper says,
Such limits constrain dispersive effects created, for example, by the spacetime foam of quantum gravity. In the context of quantum gravity, our bounds set M1c2 greater than 525 times the Planck mass, suggesting that spacetime is smooth at energies near and slightly above the Planck mass.
That sure isn't what I would expect. Now, maybe the current thinking (really, just dimensional analysis) is missing something important, but if we can push that "slightly above" to "slightly below," then I think it is would be good to consider other alternatives.
Go on the Cosmology Calculator, put in the red shift (z = 0.34) and (for the default cosmological model, which is pretty good now-a-days) you get
The light travel time was 3.751 Gyr.
The comoving radial distance, which goes into Hubble's law, is 1330.7 Mpc or 4.340 Gly.
The angular size distance DA is 993.0 Mpc or 3.2389 Gly.
One big question is, how far back can we see. We cannot see back to the big bang, so there is a limit, if we confine the question to seeing events within the mass that emerged from the big bang. And how far away is that?
If by "seeing" you mean "with photons" I do not believe that you can see before the Cosmic Microwave Background (CMB). With the standard model, the universe is 13.666 billion years since inflation, and the CMB was ~ 300,000 years since inflation, so we can see back (13.666 billion - 300,000) years.
Note that inflation may not be quick (search on "eternal inflation"), and happened very early, so I think it is better to say that "X happened N years after inflation" instead of "X happened N years after the Big Bang." If inflation was quick, then we are talking about a difference of much less than one second, out of all of those billions of years,
No, although that was entertained (by some) in the fairly long history of these bursts.
In the early days (after GRB were detected by US satellites sent up to look for nuclear explosions) there were lots of theories, as we knew basically nothing about them. The consensus was that GRB were probably fairly close to us, in the galaxy (which kept the burst energy reasonable). The early satellites could only see the brightest bursts, so there weren't many bursts observed, and statistics were very poor, so you couldn't say much more. (At this time I remember some people proposing primordial black hole explanations.) One of the major goals of the Compton Space Telescope BATSE experiment was to be sensitive enough to GRB to be able to observe hundreds to thousands of them, with decent positions, enough data so that you should be able to see the Milky Way (the galactic disk) in the burst locations (i.e., that you would see more bursts along the Milky Way in the sky than in other directions). At the time, the consensus opinion was very strongly that BATSE would see the plane of the Milky Way in the aggregate burst positions, as they accumulated.
The experiment was flown and worked well and recorded an isotropic (random) distribution of bursts. (So much for conventional wisdom.) This meant that the bursts were either very far away (and thus very powerful) or very close (and thus relatively weak, weak enough that you could only see them up to a few light years, where everything is in the galactic disk, and thus can look random in direction, the way the brightest stars in the night sky appear more-or-less random in direction). I actually toyed around with an extraterrestrial intelligence explanation for close bursts at that time (the bursts would be some side effect of power generation or space travel, which would have implied that the ETIs were close and ubiquitous), but most people started thinking about extremely distant (to be random), and thus very powerful events. (IIRC, this was bad but not quite fatal for the primordial black hole explanation, as those bursts are strong enough that you would expect to see the galactic disk in the accumulated BATSE data, but maybe you could adjust things enough to get around that.)
This conundrum was resolved by the orbiting Swift telescope, which could not only see GRB, but could report a position back to Earth quickly enough to train an optical telescope on the spot within a few seconds. This was flown, and some GRBs were observed in the optical. (This also required some serious work on rapid response optical telescopes.) Swift + optical meant that we knew their positions very accurately, so the biggest telescopes could be used to see where, exactly, they were coming from (which turned out to be distant galaxies) and thus get a red shift, and thus a distance (the GRB of the OP is apparently at a red shift of 0.34). That, among other things, showed very clearly that these bursts could not be primordial black holes (or local ETI!), as those are much too weak to see bursting across cosmological distances.
This Gamma Ray Burst (GRB) was stronger than a typical GRB, and a typical GRB is much stronger than a typical supernova, at least in the beam. This paper considers the effects of a GRB at 2 kpc, or 6000 light years, or over 100 times further away than the 50 ly supernova limit. I don't know any details of the new GRB, but if it was as bright as they are implying, it could have been dangerous from the galactic center or beyond.
There is one asterisk here - a supernova will be dangerous for some time (possibly months), while a GRB lasts seconds. A GRB, even if it totally roasts one hemisphere of a planet, would miss the other side, while a SN could get both sides. There might be second order effects from the GRB (such as some sort of nuclear winter) that could cause havoc, but a single GRB just might not be able to totally sterilize a planet from 20,000 light years away. (The 50 ly supernova limit is not that firm, either). We don't know for sure in either case, and I for one would not like to find out.
On a (very slightly) more serious note, Kardashev type III civilizations might be able to weaponize Gamma Ray Bursts, and take out an entire Galaxy the way the Death Star took out Alderaan. I suspect that even Darth Vader would find that impressive.
No. They may have detected something, and it's not gone through the pipeline yet, but Bert and Ernie were much before this event.
They were August 8, 2011 (Bert) and January 3, 2012 (Ernie).
Even if they didn't see a thing, I am sure there will be an IceCube press release about this in a few months, as they will be able to improve the GRB neutrino limit.
The brightest Gamma ray bursts (GRB) are important for quantum gravity, as the photons have a short enough wavelength and go over long enough distances that spacetime foam should give them dispersion. The best test so far is based mostly on GRB 080916C, and from what I hear this new burst may be able to do better.
A little background.
The Heisenberg uncertainty principle predicts "virtual" particles. The time part of the uncertainty principle is delta T delta E > h, where E is energy, T is time and h is Planck's constant (I am ignoring factors of 2 pi). As the time of an event (say, the time for a photon to travel one wavelength) gets shorter, the energy of the virtual particles allowed (delta E) gets bigger. For short enough time periods (i.e., near the Planck time), the energy is enough that the virtual particles are black holes, popping in and out of existence, and severely mangling the spacetime on that time / distance scale. This mangling is called "spacetime foam". The wavelength of the GRB photons is much larger than the Planck distance (roughly, the virtual black holes should live for a Planck time and have an event horizon the size of the Planck distance), but the GRBs are very far away, and the GRB photons pass over many, many, Planck distances along the way, and each adds a little nudge. This effect depends on the photon energy (it is larger for higher energies, as these are smaller photons), thus the "dispersion" mentioned in these papers.
The really cool thing is that the existing dispersion limits seem to be less than many people's expectations. If this is confirmed (and pushed down to a little smaller distance scale), then the conventional spacetime foam ideas I outlined above here may not be correct. This, in fact, may be the first evidence for the "holographic principle," which implies a smoother spacetime than the above ideas. In any case, this is the only way we have at present to say anything experimental about quantum gravity, so the more data the better.
Even though I would love to see every racketeer prosecuted to the full extent of the law, a more useful approach would be to end the war on sharing. Only legalizing non-commercial file-sharing will protect the public from these sharks.
That is something that a local prosecutor cannot do. They can, however, prosecute malfeasance in their trials, and so should be encouraged to do so.
Here in Northern Virginia, the police will rarely stop you (for speeding) if you are not going over the limit; the problem is the limits, which can vary rapidly and arbitrarily. The worst example around here is Dulles Airport, where the access road speed limit goes from 55 to 30 in a very short distance just before a bend, perfect for disguising a radar trap.
Also, coming from the South, I have to wonder if the strictness of your Sheriff varies by the way you look...
Note : DRM is targeted against the physical possessor of materials, and is thus quite different from encryption, although they are commonly confused, and of course there are technological similarities.
As the laws are currently set up, and as structures have grown up around those laws (and influencing those laws), no.
Change the ground rules (for example, abolish all copyright), and the answer becomes a solid maybe, depending on the details of what has replaced what we currently have.
Say WHAT? There isn't even consensus that these cosmic neutrinos are either neutrinos or cosmic, much less where they come from. Extra-galactic is reasonable, but I would put it more in the 20-30% range, not 99%.
Though the two events could be a first indication of an astrophysical neutrino flux, the moderate significance and the uncertainties on the expected atmospheric background from neutrinos produced in the decay of charmed mesons do not allow for a firm conclusion at this point.
The sequester is not bunk - any time you mess with an agency's funding, it will cause issues. (Plans get made in advance, hiring and other spending gets committed to, etc.) However, there seems to be an aspect of a "statue of liberty" play here. In this context, this does not refer to a football play, but to a (possibly hypothetical) Park Service tendency to respond to budget cuts by closing the Statue of Liberty, instead of some remote park entrances in the back-of-beyond.
Statue of Liberty plays are used because they get people's attention, which the FAA has certainly done.
There are a lot of noodle restaurants in China. Based on my extremely limited sampling, for most of them $1000 USD would be a hefty expense.
There are also a lot of cheap (but not quite as cheap) noodle restaurants in Japan (and Taiwan) as well - I wonder if this invention might find more of a market there.
Of course, this is a way of concentrating people's minds, and getting attention to the subject. He is a theoritician, not an experimentalist, so he gives in fairly easily.
Hawking lost a famous wager to Preskill in 2004 in a debate over whether or not black holes destroy information (theory suggests they do not, opposing Hawking's argument).
The theory that made him give in is "M-theory," which has absolutely no experimental evidence in favor of it. He decided he lost the wager; the debate itself is very much still open, and was even in the news lately (search on "black hole firewall").
This guys world view is obviously based on what he learned in kindergarten.
I would agree. What he learned in Kindergarten was that his father was quite wealthy, and he would inherit someday. I don't think he needed to know more.
Slashdot Mirror
I have seen it for years, and I am not a Star Wars fan (not since Episode 1).
Yes. Trying to constrain spacetime foam with these photons (see my post way above) is harder than trying to learn something about atoms using your hands (only 10 orders of magnitude or so), and yet over 3 billion years of travel, even little things add up.
:)
So basically, the spacetime foam theory is not playing out?
It's too soon to be sure, but, as the paper says,
That sure isn't what I would expect. Now, maybe the current thinking (really, just dimensional analysis) is missing something important, but if we can push that "slightly above" to "slightly below," then I think it is would be good to consider other alternatives.
Go on the Cosmology Calculator, put in the red shift (z = 0.34) and (for the default cosmological model, which is pretty good now-a-days) you get
The light travel time was 3.751 Gyr.
The comoving radial distance, which goes into Hubble's law, is 1330.7 Mpc or 4.340 Gly.
The angular size distance DA is 993.0 Mpc or 3.2389 Gly.
If by "seeing" you mean "with photons" I do not believe that you can see before the Cosmic Microwave Background (CMB). With the standard model, the universe is 13.666 billion years since inflation, and the CMB was ~ 300,000 years since inflation, so we can see back (13.666 billion - 300,000) years.
Note that inflation may not be quick (search on "eternal inflation"), and happened very early, so I think it is better to say that "X happened N years after inflation" instead of "X happened N years after the Big Bang." If inflation was quick, then we are talking about a difference of much less than one second, out of all of those billions of years,
If you are not suspicious about Google you are not paying attention.
If the policy is evil, this would become the Do-No-Discoverable-Good patent, and we have enough of that already.
Very nice write-up.
No, although that was entertained (by some) in the fairly long history of these bursts.
In the early days (after GRB were detected by US satellites sent up to look for nuclear explosions) there were lots of theories, as we knew basically nothing about them. The consensus was that GRB were probably fairly close to us, in the galaxy (which kept the burst energy reasonable). The early satellites could only see the brightest bursts, so there weren't many bursts observed, and statistics were very poor, so you couldn't say much more. (At this time I remember some people proposing primordial black hole explanations.) One of the major goals of the Compton Space Telescope BATSE experiment was to be sensitive enough to GRB to be able to observe hundreds to thousands of them, with decent positions, enough data so that you should be able to see the Milky Way (the galactic disk) in the burst locations (i.e., that you would see more bursts along the Milky Way in the sky than in other directions). At the time, the consensus opinion was very strongly that BATSE would see the plane of the Milky Way in the aggregate burst positions, as they accumulated.
The experiment was flown and worked well and recorded an isotropic (random) distribution of bursts. (So much for conventional wisdom.) This meant that the bursts were either very far away (and thus very powerful) or very close (and thus relatively weak, weak enough that you could only see them up to a few light years, where everything is in the galactic disk, and thus can look random in direction, the way the brightest stars in the night sky appear more-or-less random in direction). I actually toyed around with an extraterrestrial intelligence explanation for close bursts at that time (the bursts would be some side effect of power generation or space travel, which would have implied that the ETIs were close and ubiquitous), but most people started thinking about extremely distant (to be random), and thus very powerful events. (IIRC, this was bad but not quite fatal for the primordial black hole explanation, as those bursts are strong enough that you would expect to see the galactic disk in the accumulated BATSE data, but maybe you could adjust things enough to get around that.)
This conundrum was resolved by the orbiting Swift telescope, which could not only see GRB, but could report a position back to Earth quickly enough to train an optical telescope on the spot within a few seconds. This was flown, and some GRBs were observed in the optical. (This also required some serious work on rapid response optical telescopes.) Swift + optical meant that we knew their positions very accurately, so the biggest telescopes could be used to see where, exactly, they were coming from (which turned out to be distant galaxies) and thus get a red shift, and thus a distance (the GRB of the OP is apparently at a red shift of 0.34). That, among other things, showed very clearly that these bursts could not be primordial black holes (or local ETI!), as those are much too weak to see bursting across cosmological distances.
This Gamma Ray Burst (GRB) was stronger than a typical GRB, and a typical GRB is much stronger than a typical supernova, at least in the beam. This paper considers the effects of a GRB at 2 kpc, or 6000 light years, or over 100 times further away than the 50 ly supernova limit. I don't know any details of the new GRB, but if it was as bright as they are implying, it could have been dangerous from the galactic center or beyond.
There is one asterisk here - a supernova will be dangerous for some time (possibly months), while a GRB lasts seconds. A GRB, even if it totally roasts one hemisphere of a planet, would miss the other side, while a SN could get both sides. There might be second order effects from the GRB (such as some sort of nuclear winter) that could cause havoc, but a single GRB just might not be able to totally sterilize a planet from 20,000 light years away. (The 50 ly supernova limit is not that firm, either). We don't know for sure in either case, and I for one would not like to find out.
Very appropriate for Star Wars Day!
On a (very slightly) more serious note, Kardashev type III civilizations might be able to weaponize Gamma Ray Bursts, and take out an entire Galaxy the way the Death Star took out Alderaan. I suspect that even Darth Vader would find that impressive.
No. They may have detected something, and it's not gone through the pipeline yet, but Bert and Ernie were much before this event.
They were August 8, 2011 (Bert) and January 3, 2012 (Ernie).
Even if they didn't see a thing, I am sure there will be an IceCube press release about this in a few months, as they will be able to improve the GRB neutrino limit.
The brightest Gamma ray bursts (GRB) are important for quantum gravity, as the photons have a short enough wavelength and go over long enough distances that spacetime foam should give them dispersion. The best test so far is based mostly on GRB 080916C, and from what I hear this new burst may be able to do better.
A little background.
The Heisenberg uncertainty principle predicts "virtual" particles. The time part of the uncertainty principle is delta T delta E > h, where E is energy, T is time and h is Planck's constant (I am ignoring factors of 2 pi). As the time of an event (say, the time for a photon to travel one wavelength) gets shorter, the energy of the virtual particles allowed (delta E) gets bigger. For short enough time periods (i.e., near the Planck time), the energy is enough that the virtual particles are black holes, popping in and out of existence, and severely mangling the spacetime on that time / distance scale. This mangling is called "spacetime foam". The wavelength of the GRB photons is much larger than the Planck distance (roughly, the virtual black holes should live for a Planck time and have an event horizon the size of the Planck distance), but the GRBs are very far away, and the GRB photons pass over many, many, Planck distances along the way, and each adds a little nudge. This effect depends on the photon energy (it is larger for higher energies, as these are smaller photons), thus the "dispersion" mentioned in these papers.
The really cool thing is that the existing dispersion limits seem to be less than many people's expectations. If this is confirmed (and pushed down to a little smaller distance scale), then the conventional spacetime foam ideas I outlined above here may not be correct. This, in fact, may be the first evidence for the "holographic principle," which implies a smoother spacetime than the above ideas. In any case, this is the only way we have at present to say anything experimental about quantum gravity, so the more data the better.
Anywhere in the Galaxy, if it were pointed in our direction. Maybe anywhere in the Local Group, if it were pointed right at us.
Even though I would love to see every racketeer prosecuted to the full extent of the law, a more useful approach would be to end the war on sharing. Only legalizing non-commercial file-sharing will protect the public from these sharks.
That is something that a local prosecutor cannot do. They can, however, prosecute malfeasance in their trials, and so should be encouraged to do so.
30 miles East of where I live right now would put me in salt water. Yes, salt water is tough on cameras, but...
Here in Northern Virginia, the police will rarely stop you (for speeding) if you are not going over the limit; the problem is the limits, which can vary rapidly and arbitrarily. The worst example around here is Dulles Airport, where the access road speed limit goes from 55 to 30 in a very short distance just before a bend, perfect for disguising a radar trap.
Also, coming from the South, I have to wonder if the strictness of your Sheriff varies by the way you look...
Note : DRM is targeted against the physical possessor of materials, and is thus quite different from encryption, although they are commonly confused, and of course there are technological similarities.
As the laws are currently set up, and as structures have grown up around those laws (and influencing those laws), no.
Change the ground rules (for example, abolish all copyright), and the answer becomes a solid maybe, depending on the details of what has replaced what we currently have.
MKS units are always appropriate, especially for something aimed at the popular level.
Say WHAT? There isn't even consensus that these cosmic neutrinos are either neutrinos or cosmic, much less where they come from. Extra-galactic is reasonable, but I would put it more in the 20-30% range, not 99%.
From the ABSTRACT of the actual paper:
The sequester is not bunk - any time you mess with an agency's funding, it will cause issues. (Plans get made in advance, hiring and other spending gets committed to, etc.) However, there seems to be an aspect of a "statue of liberty" play here. In this context, this does not refer to a football play, but to a (possibly hypothetical) Park Service tendency to respond to budget cuts by closing the Statue of Liberty, instead of some remote park entrances in the back-of-beyond.
Statue of Liberty plays are used because they get people's attention, which the FAA has certainly done.
There are a lot of noodle restaurants in China. Based on my extremely limited sampling, for most of them $1000 USD would be a hefty expense.
There are also a lot of cheap (but not quite as cheap) noodle restaurants in Japan (and Taiwan) as well - I wonder if this invention might find more of a market there.
He is wrong, on pretty much every level, even the visual.
Of course, this is a way of concentrating people's minds, and getting attention to the subject. He is a theoritician, not an experimentalist, so he gives in fairly easily.
The theory that made him give in is "M-theory," which has absolutely no experimental evidence in favor of it. He decided he lost the wager; the debate itself is very much still open, and was even in the news lately (search on "black hole firewall").
This guys world view is obviously based on what he learned in kindergarten.
I would agree. What he learned in Kindergarten was that his father was quite wealthy, and he would inherit someday. I don't think he needed to know more.