But the rooftop systems are "essentially invisible to us," says Ching, "because they sit behind a customer's meter and we don't have a means to directly measure them."
Yes, you do.
Here is a business model for you: pay a low rate for electricity from sources you can't monitor, pay full* rate for electricity where you put a little Internet of Things gizomo on the line to measure (or even control) output from the source. You could even get the homeowners to pay for the gizmo out of future revenue.
* Yes, I know "full rate" also has its problems, but it'll get set somehow and the point is only IoT installed houses will get that rate.
"Dark matter" as an effect is very well established. It is a sign of a failure in our models of physics. That failure could be in the microphysics (thus, various particle models, such as WIMPs), or in the macrophysics (i.e., in general relativity, the model for gravity, which is modified by theories such as MOND).
Now, as it happens, these sorts of galaxy cluster collision observations are probably the strongest test of MOND type theories - it is hard to see how a failure of gravity would get separated from the matter causing the gravity. MOND is not yet firmly ruled out, but it does look a lot less plausible.
WIMPs are actually an old explanation of dark matter, probably on the way out unless LHC can pull out a supersymmetric particle in their new run.
In any case, WIMPs only interact through the weak interaction, so it is generally assumed that these "self-interacting" particles are not WIMPs, but some new form of SIDM.
I am currently a sophomore in high school, and have recently gotten very interested in Physics, Programming, and the study of space. Is there any advice for an aspiring astronomer that you feel would be particularly helpful?
So they could be out by 1,300 light years on a distance of 'only' 10,200? That doesn't sound very accurate to me. Does this have implications for calculations of the size, and therefore the age, of the visible universe?
I broke the rules and RTFA, this is the first time that they have managed to combine an Earth-based observation and a space-based one separated by far enough from each other to give a reasonably accurate baseline for an accurate measurement of both distance and mass. From the article:
Calculations estimated it to be 10,200 (+/- 1,300) light-years away. . . These observations also allowed the mass of the object to be measured — around 0.23 solar masses
Not quite. If you read further, you see that the key word is that it is first for a "isolated" (i.e., single) star. Dong et al. did this in 2007, but for a binary star.
I must sat that I dislike "firstitis," both in science and on Slashdot. However, these are not easy measurements and this is still quite an accomplishment.
This is known as microlensing parallax, and was first done 1995. Parallax breaks lensing degeneracies, enabling the determination of distance,
Now, you may quibble about this particular distance measurement, but it's been done for 20 years now. Routinely. And, yes, its been done from space before too.
My guess is that some needed qualifiers were lost between the astronomer's mouth and the headline writers keyboard, but it ain't first.
Well, sure. I have tested General Relativity, and would love to have found a case where it was not "good enough." But, that is different from an internal contradiction, which as far as we know GR doesn't have.
There have been several theories built on that assumption, most prominently one called MOND (MOdified Newtonian Dynamics), but more recently one that builds on relativity rather than Newtonian gravity/dynamics.
But none of these theories (hypotheses?) have gained much acceptance from the physics community, as far as I know.
Yes, and one reason is that they find it hard to model these kinds of galaxy cluster observations in MOND / TeVeS without assuming there is also some dark matter or some other non-MOND effect involved. Now, that could be (and MOND proponents will point out that standard CMD also has its problems, e.g., with the core/cusp problem, and we don't throw out CDM every time such a problem is encountered), but it certainly takes some of the shine off of the theory.
From my perspective, it hardly changes a thing (it lowers the cross section / mass constraint a little, but not even an order of magnitude). But, then, I'm not a WIMP guy.
Math proofs are meaningless without physical observations to back them up.
Fully agree. And, as it happens, General Relativity has a massive amount of physical observation backing it up, and no physical observations contradicting* it.
* If you believe in MOND / TeVeS, then the dark matter observations contradict GR. Let's just say that there is not yet consensus around that view.
That the thing about dark matter... it has a perfectly reasonable explanation (WIMPs). It's not that weird of a "thing".
I dunno. Usually when a theory requires more and more unseen entities over time it's a sign that it's time to replace the theory. We know General Relativity is incomplete, both because it doesn't take into account quantum effects and because it has internal contradictions - specifically, it assumes a continuous spacetime geometry but predicts non-continuous points (black hole singularities).
That is not thought to be an internal contradiction of General Relativity, as, even though GR does have singularities, thanks to event horizons and cosmological censorship, there are no known cases where you can use these singularities to derive multiple different estimates of the same observational quantity (which is what having an inconsistent physical model means). I don't believe that there are any mathematical proofs of this, but I suspect you would have to come up with a counter-example if you wanted to convince people GR was self-contradictary.
Dark energy is just the latest name for the Cosmological Constant
You know, I'm as happy as anyone else that physicists have been able to do so much with their models, but what kind of navel-gazing mathurbation is this?
Dark energy is an observed physical phenomenon.
The cosmological constant is a term in an equation. It's a very good equation, mind you, but a lot of very good equations have later turned out to be wrong or good for only a special class of phenomena. Equations can predict, but they don't prove anything. It's also worth noting that the cosmological constant was supposed to predict a force that would hold the universe together. Dark energy is a force that is tearing the universe apart. Someone clever pointed out that hey, that works if you just flip the sign of the cosmological constant but I'm not sure I'd call that a win.
This is physics. Everything is a term in an equation.
The cosmological constant is the only free parameter in Einstein's equations. The. Only. One. And, it fits exactly all of the available data. Unless and until that changes, there is no good reason to believe to believe that we do not live in a de Sitter space.
The WIMP miracle is over; unless the LHC finds success with its Hail Mary pass, interest in WMPs will inevitably decline, and people will look (are looking) at other explanations for Dark Matter.
Dark Energy, on the other hand, is just a cosmological constant. Nothing mysterious (from a General Relativistic standpoint) about it at all.
Not how business is done. Nor do you give ultimatums to governments. You let your intentions be known but do not threaten (businesses should not threaten government passing laws.)
You obviously don't have much experience in this area.
Most hotel and convention contracts (and, I have dealt with such) have enough wiggle room in the "Force Majeure" clauses that they will be able to void them. (IANAL, and TINLA.) However, it is the deposits that would be at risk; they could be soaked up in fees, etc., as could things like hotel commission payments for the last meeting. For a sufficiently large meeting on an annual cycle, there is generally no or almost no time where there is not money either deposited or owed; those payments would be at risk.
To say more, you would need to know just what the contracts said, and those are generally not made public.
Slashdot Mirror
America, a nation of Stakhanovites.
My point is - would anyone have cared if he didn't trigger a 1000 pt market slide?
There are lots of things you can get away with, as long as you don't cause a panic and make the evening news.
Many people with rooftop solar are not grid neutral, so the batteries would beed external charging.
Yes, you do.
Here is a business model for you: pay a low rate for electricity from sources you can't monitor, pay full* rate for electricity where you put a little Internet of Things gizomo on the line to measure (or even control) output from the source. You could even get the homeowners to pay for the gizmo out of future revenue.
* Yes, I know "full rate" also has its problems, but it'll get set somehow and the point is only IoT installed houses will get that rate.
You should look into MOND.
"Dark matter" as an effect is very well established. It is a sign of a failure in our models of physics. That failure could be in the microphysics (thus, various particle models, such as WIMPs), or in the macrophysics (i.e., in general relativity, the model for gravity, which is modified by theories such as MOND).
Now, as it happens, these sorts of galaxy cluster collision observations are probably the strongest test of MOND type theories - it is hard to see how a failure of gravity would get separated from the matter causing the gravity. MOND is not yet firmly ruled out, but it does look a lot less plausible.
WIMPs are actually an old explanation of dark matter, probably on the way out unless LHC can pull out a supersymmetric particle in their new run.
In any case, WIMPs only interact through the weak interaction, so it is generally assumed that these "self-interacting" particles are not WIMPs, but some new form of SIDM.
It's probably not wise to put a lot of weight on a discovery that is only 2.5 sigma.
I am currently a sophomore in high school, and have recently gotten very interested in Physics, Programming, and the study of space. Is there any advice for an aspiring astronomer that you feel would be particularly helpful?
Take as much math as you possibly can.
So they could be out by 1,300 light years on a distance of 'only' 10,200? That doesn't sound very accurate to me. Does this have implications for calculations of the size, and therefore the age, of the visible universe?
No.
I broke the rules and RTFA, this is the first time that they have managed to combine an Earth-based observation and a space-based one separated by far enough from each other to give a reasonably accurate baseline for an accurate measurement of both distance and mass. From the article:
Calculations estimated it to be 10,200 (+/- 1,300) light-years away. . . These observations also allowed the mass of the object to be measured — around 0.23 solar masses
Not quite. If you read further, you see that the key word is that it is first for a "isolated" (i.e., single) star. Dong et al. did this in 2007, but for a binary star.
I must sat that I dislike "firstitis," both in science and on Slashdot. However, these are not easy measurements and this is still quite an accomplishment.
This is known as microlensing parallax, and was first done 1995. Parallax breaks lensing degeneracies, enabling the determination of distance,
Now, you may quibble about this particular distance measurement, but it's been done for 20 years now. Routinely. And, yes, its been done from space before too.
My guess is that some needed qualifiers were lost between the astronomer's mouth and the headline writers keyboard, but it ain't first.
Well, sure. I have tested General Relativity, and would love to have found a case where it was not "good enough." But, that is different from an internal contradiction, which as far as we know GR doesn't have.
There have been several theories built on that assumption, most prominently one called MOND (MOdified Newtonian Dynamics), but more recently one that builds on relativity rather than Newtonian gravity/dynamics.
But none of these theories (hypotheses?) have gained much acceptance from the physics community, as far as I know.
Yes, and one reason is that they find it hard to model these kinds of galaxy cluster observations in MOND / TeVeS without assuming there is also some dark matter or some other non-MOND effect involved. Now, that could be (and MOND proponents will point out that standard CMD also has its problems, e.g., with the core/cusp problem, and we don't throw out CDM every time such a problem is encountered), but it certainly takes some of the shine off of the theory.
What objects are moving away from us faster than light and how was this determined?
None. That poster was overly enthusiastic.
I don't have the article in the mail yet, but I'm guessing that's new. At the very least, Weakly Interacting is now Really Weakly Interacting.
Here you go.
From my perspective, it hardly changes a thing (it lowers the cross section / mass constraint a little, but not even an order of magnitude). But, then, I'm not a WIMP guy.
Math proofs are meaningless without physical observations to back them up.
Fully agree. And, as it happens, General Relativity has a massive amount of physical observation backing it up, and no physical observations contradicting* it.
* If you believe in MOND / TeVeS, then the dark matter observations contradict GR. Let's just say that there is not yet consensus around that view.
I dunno. Usually when a theory requires more and more unseen entities over time it's a sign that it's time to replace the theory. We know General Relativity is incomplete, both because it doesn't take into account quantum effects and because it has internal contradictions - specifically, it assumes a continuous spacetime geometry but predicts non-continuous points (black hole singularities).
That is not thought to be an internal contradiction of General Relativity, as, even though GR does have singularities, thanks to event horizons and cosmological censorship, there are no known cases where you can use these singularities to derive multiple different estimates of the same observational quantity (which is what having an inconsistent physical model means). I don't believe that there are any mathematical proofs of this, but I suspect you would have to come up with a counter-example if you wanted to convince people GR was self-contradictary.
Yeah, but that is widely considered not to be good enough.
Dark energy is just the latest name for the Cosmological Constant
You know, I'm as happy as anyone else that physicists have been able to do so much with their models, but what kind of navel-gazing mathurbation is this?
Dark energy is an observed physical phenomenon.
The cosmological constant is a term in an equation. It's a very good equation, mind you, but a lot of very good equations have later turned out to be wrong or good for only a special class of phenomena. Equations can predict, but they don't prove anything. It's also worth noting that the cosmological constant was supposed to predict a force that would hold the universe together. Dark energy is a force that is tearing the universe apart. Someone clever pointed out that hey, that works if you just flip the sign of the cosmological constant but I'm not sure I'd call that a win.
This is physics. Everything is a term in an equation.
The cosmological constant is the only free parameter in Einstein's equations. The. Only. One. And, it fits exactly all of the available data. Unless and until that changes, there is no good reason to believe to believe that we do not live in a de Sitter space.
That's exactly backwards.
The WIMP miracle is over; unless the LHC finds success with its Hail Mary pass, interest in WMPs will inevitably decline, and people will look (are looking) at other explanations for Dark Matter.
Dark Energy, on the other hand, is just a cosmological constant. Nothing mysterious (from a General Relativistic standpoint) about it at all.
No. This really applies _to_ WIMPs. It doesn't apply to condensed dark matter, or to axions.
Not how business is done. Nor do you give ultimatums to governments. You let your intentions be known but do not threaten (businesses should not threaten government passing laws.)
You obviously don't have much experience in this area.
You can put money on two things
- this will be used to deny service to blacks (safe bet, as it already has been).
- that will not go over well, in a burn the place down sort of way.
And, at that point, it will probably be thrown out in court or amended out of existence by the legislature.
Most hotel and convention contracts (and, I have dealt with such) have enough wiggle room in the "Force Majeure" clauses that they will be able to void them. (IANAL, and TINLA.) However, it is the deposits that would be at risk; they could be soaked up in fees, etc., as could things like hotel commission payments for the last meeting. For a sufficiently large meeting on an annual cycle, there is generally no or almost no time where there is not money either deposited or owed; those payments would be at risk.
To say more, you would need to know just what the contracts said, and those are generally not made public.
All I can say is, I hope his checks cashed.