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Comment: Nonlinear Gravity [Re:Altering General Relativity] (Score 1) 356

by Geoffrey.landis (#48005643) Attached to: Physicist Claims Black Holes Mathematically Don't Exist

As I understand it GR does *not* factor in the energy within the gravitational field as creating it's own "secondary" field

It is built into the theory. This is why GR is a nonlinear theory-- which is precisely what makes it so difficult to solve.

- if it did gravity would no longer follow the inverse-square law near singularities,

Correct. Gravity only follows inverse square law in the weak-field limit. Orbits in 1/r2 potentials are ellipses. Orbits in Schwartzschild geometry are not ellipses. Right there you know that Einsteinian gravity differs from Newtonian 1/r2 gravity.

I actually would like to spend some time to elucidate how it is that nonlinearity in GR means that it incorporates the effect of gravity on gravity-- but I'm afraid I just don't have the time to spare at the moment.

... Bottom line, we have Einstein himself on record saying he chose to ignore the energy in a gravitational field as "double counting", are you really going to argue the point with his ghost?

Not only would I not argue, I would agree with him. Since the gravitational effect of gravity is already accounted for in general relativity, it would be double counting to count it again.

Comment: Feedback loop [Re:LEDs] (Score 1) 595

by Geoffrey.landis (#48004649) Attached to: The Great Lightbulb Conspiracy

But, of course, everybody wants to buy the cheapest ones, not ones tested to long lifetime.

People buy the cheapest because they don't trust the 'rating' on the package. They know it will die 'early' anyway so they might as well be cheated out of $5 rather than $10.

Yep. That's a vicious circle, of course, a feedback look that results in a "race to the bottom."

As I said, what is needed is a good (and trustworthy) rating agency to test and qualify the bulbs.

Comment: Altering General Relativity [Re:Density] (Score 1) 356

by Geoffrey.landis (#48004621) Attached to: Physicist Claims Black Holes Mathematically Don't Exist

...

As for the stability of a dust cloud - if it's "stationary", certainly. But how about if it were orbitting an ancient neutron star or other massive non-luminous object in an organized manner? A "lynch pin" as it were to impose order on what would otherwise devolve into a chaotic system and collapse.

I don't know what you mean by "in an organized manner." You mean, what if a superior civilization put each grain of dust on exactly such a trajectory that dust/dust interactions don't destabilize the cloud? OK.

As for ordinary, non-"organized" dust clouds, if there is any interaction between dust grains, and no internal source of energy to keep it from collapsing, a dust cloud large enough to be self-gravitating is unstable.

As for new physics for a "solid" object of that mass - we wouldn't even have to go very far. All we have to do is [proposes altered version of General Relativity] ....

That would be new physics. General Relativity does, of course, account for the gravitational energy of gravitational fields; that's why it's nonlinear. On the face of it, your proposed revision to general relativity's equations violates conservation of energy. There may be some way to avoid that-- but if you do, this is new physics.

Comment: Directionality [Re:LEDs] (Score 1) 595

by Geoffrey.landis (#48002979) Attached to: The Great Lightbulb Conspiracy

I got a 3 pack of LED lights to play with about a year ago from Feit. No problems with those, although it's still too early to tell how I'll fare. The light is a little more directional than the CFLs but I like the color temp better.

You can get directional or non-directional LED bulbs. I like the fact that you can get directional LEDs: for applications like overhead can lights, this nearly doubles the effective brightness. But most of the LED lamps you buy take deliberate measures to be non-directional, to make them screw-in replacements for incandescents

Color temperature is something you can pick. I like the "daylight" color personally--5000K-- but my wife prefers the warmer color temperatures, down in the 2700K range.

Comment: LEDs (Score 5, Informative) 595

by Geoffrey.landis (#48002025) Attached to: The Great Lightbulb Conspiracy

The Department of Energy had a pretty rigorous test regimen set up for testing LED bulbs.
http://www.lightingprize.org/6...
What is needed is a good (and trustworthy) rating agency to test and qualify the bulbs.

But, of course, everybody wants to buy the cheapest ones, not ones tested to long lifetime.

For what it's worth, I have about 60 LED bulbs in my house, from about fifteen maufacturers. So far, four have failed.

Further - no viable light bulb replacements will work with dimmer switches (Which my house has many).

That was true five years ago-- these days it seems all of then are rated to work with dimmers . I have some Philips LED bulbs on a dimmer in the dining room-- they work fine.

Comment: Density [Re:But do we see them?] (Score 1) 356

by Geoffrey.landis (#48001837) Attached to: Physicist Claims Black Holes Mathematically Don't Exist

Density is not the determinant a black hole. Large black holes have very low densities.

From the size and mass, we can rule out pretty much all the other possibilities. (Small but massive dust clouds are gravitationally unstable.) So if it's not a black hole, it must be something else, and that something else is either new physics, or a manifestation of old physics that we've been insufficiently clever to figure out yet.

Comment: Re:About Time (Score 1) 173

by Geoffrey.landis (#47996877) Attached to: Solar System's Water Is Older Than the Sun

Please describe what an earth without form and void is supposed to mean. He created a void?????

Well, of course, that's not actually what Genesis said. What Genesis said was that the earth was tohu v' bohu. ( -- let's see how /. does with Hebrew). So, what you're really asking is, what does it mean for the Earth to be bohu? He created a bohu? (Or maybe bohu was already there?)

My personal explanation, the author went with bohu simply because it was a good rhyme with tohu. When you're a poet, sometimes you just have to go with the easy rhyme.

Comment: But do we see them? (Score 2) 356

by Geoffrey.landis (#47986103) Attached to: Physicist Claims Black Holes Mathematically Don't Exist

How is it at odds with observations? We've (indirectly) observed some of objects consistent with our theories of how black holes would behave, but to the best of my knowledge we've never observed the *formation* of such an object.

The headline-- Black holes don't exist-- is at odds with our observations: we see things that appear to be black holes.

The actual summary is not at odds with our observations: the summary says that stellar collapse doesn't form black holes, and we don't have observations to say know how the black holes we seem to be observing were formed.

Now, you could go on and ask whether the things that we see which we are interpreting as black holes might be something else. But that would require a new theory that could explain how the massive, compact objects we see could exist, and not be a black hole. I don't believe that, at the moment, we have any other candidates.

With that said, of course we can't see a black hole itself. But we can see the stuff orbiting it, and that can tell us its mass and size, which is enough to tell what it is.

Comment: Headline slightly inaccurate (Score 5, Informative) 356

by Geoffrey.landis (#47984957) Attached to: Physicist Claims Black Holes Mathematically Don't Exist

The headline-- black holes don't exist-- is at odds with the actual article.

The article doesn't say the mathematicians said that black holes don't exist: it says they showed black holes aren't formed by the collapse of massive stars. Black holes such as the ones at the nuclei of galaxies may very well be formed by other processes.

--even if it were true that black holes don't exist, by the way, it doesn't solve the problem of the incompatibility of general relativity with quantum mechanics. At best it would solve the black hole information paradox; but since it still incorporates Hawking radiation in the solution, it doesn't even solve that.

Comment: Re:Illegal to use proxy services [Re: So-to-speak (Score 1) 418

by Geoffrey.landis (#47914717) Attached to: Comcast Allegedly Asking Customers to Stop Using Tor

The straightforward reading, however, is that it is forbidden to use proxy services. You're also not allowed to run them, but that's specified separately.

No that's not a straightforward reading at all.

Lets drop the 'or run' to simplify it slightly and read that:

You're right: if you change what it says by deleting some of the words, then it says something different.

In the next sentence, it says in particular what you're not allowed to use or run, including proxy services.

Use or run: It's not merely that you're not allowed to run proxy services: you're not allowed to use them, either.

If that's stupid-- well, how about that.

As I said: the interpretation of this text could be ambiguous. You could do the lawyer thing and claim to interpret it the way you say. But the clear straightforward text is: proxies are listed on the list of things you are specifically not allowed to use or run.

If you think the system is working, ask someone who's waiting for a prompt.

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