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Comment: Re:what if... (Score 1) 227

by mbone (#49362193) Attached to: Dark Matter Is Even More of a Mystery Than Expected

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.

Comment: Re:WIMPs (Score 1) 227

by mbone (#49362155) Attached to: Dark Matter Is Even More of a Mystery Than Expected

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.

Comment: Re:WIMPs (Score 1) 227

by mbone (#49362143) Attached to: Dark Matter Is Even More of a Mystery Than Expected

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.

Comment: Re:WIMPs (Score 1) 227

by mbone (#49361765) Attached to: Dark Matter Is Even More of a Mystery Than Expected

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.

Comment: Re:WIMPs (Score 1) 227

by mbone (#49361719) Attached to: Dark Matter Is Even More of a Mystery Than Expected

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.

Comment: Re:WIMPs (Score 1) 227

by mbone (#49361693) Attached to: Dark Matter Is Even More of a Mystery Than Expected

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.

Comment: This will be used against blacks (Score 1) 877

by mbone (#49338675) Attached to: Gen Con Threatens To Leave Indianapolis Over Religious Freedom Bill

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.

Comment: Re:Idle threats? (Score 1) 877

by mbone (#49338427) Attached to: Gen Con Threatens To Leave Indianapolis Over Religious Freedom Bill

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.

Comment: Re:Go nuclear (Score 1) 91

by mbone (#49232361) Attached to: Dry-Ice Heat Engines For Martian Colonists

Could not compact nuclear engines (eg. similar to those on submarines or on earlier probes like Voyager) not solve the energy problem for Mars? Are we so superstitious of nuclear power that we'd give up a perfectly good, long-term, powerful source without even considering it as an option? Nuclear power can and has been launched into space before, and as long as the risks of launch failure are mitigated (eg. launch over open ocean) then dry ice sublimation engines are not needed.

The SNAP 10A reactor weighed 300 kg, was flown in 1965, and produced 30 kW of heat power. In the Apollo days, there were serious plans to power lunar bases through the long lunar night with CANDLE type reactors, also known as traveling wave reactors, which have no moving parts and could be just stuck in a hole in the ground to provide 10's or 100's of kW for decades. These reactors are not particularly "hot" before they are turned on, and shouldn't produce an unusual launch risk (as they would not be launched hot).

Money will say more in one moment than the most eloquent lover can in years.

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