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Comment Re:Science grows more powerful? (Score 1) 223

So far as I can tell, science grows more powerful in each of two different but interrelated ways.

1. As the experimental data come in, the theories must change so that they accurately predict the results from an ever wider set of experimental circumstances.

2. Occasionally, there is a theoretical improvement that both increases the range of predicted circumstances and simplifies at some level the overall conceptual framework.

So long as civilization does not altogether collapse, and the various scientific communities along with it, neither of these two senses of scientific accomplishment depends on funding, but the rate at which science becomes more powerful does depend on funding.

Comment Re:Latency? (Score 1) 228

That's a really good question.

Although I've never played with VOIP, I have been watching from the sidelines.

I have noticed that a typical cell-phone conversation has noticeable latency. It's bad enough so that, when I'm calling from my cell phone, I try to call a land-line if possible. I don't want to incur the full latency of a cell-to-cell call.

I have often wondered what the source of the latency is. Does one handset have worse latency than another because of variable processing power? Or is the latency dominated by delays in processing at the tower? Or somewhere else? Is the latency asymmetric? For example, is it mostly on the encoding side in the handset and not so much on the decoding side? It would be cool if an expert would drop by this thread to enlighten me. :^)

Anyway, if latency were a real issue for VOIP (and I have no experience to say one way or the other), then, even if the audio fidelity of what comes through were substantially greater than that of a land line, I'd still prefer a land line for a real-time conversation.

Comment Re:Gravity model (Score 1) 221

We cannot ever rightly say that general relativity is true, for it is a
scientific theory. A scientific theory is not something that can be
proved true, though it can be proved false.

In the hundred years or so since Einstein's introduction of general
relativity, no observation has produced data that would rule out general
relativity from its status as a candidate for the true description of
gravity. So in a loose sense, it still "holds true". But such wording
can be subtly confusing and, in my opinion, should be discouraged.

No experiment---not even any experiment related to quantum
mechanics---no experiment has exposed flaws in general relativity. It
is well known that general relativity and quantum mechanics are
incompatible. They cannot both be true. Still, no experiment yet
devised has been able to rule out either of those great theoretical
foundations of modern physics.

A theory of everything would need to be inconsistent, in some sense,
with either GR or with QM or with both.

Comment Re:Gravity model (Score 3, Informative) 221

It's only a very crude analogy.

That's a good point, and it should be elaborated as the proper response
to cyberchondriac.

cyberchondriac identifies the grid-bent-by-balls as "the current popular
gravity model". It is in fact a popular model, which I remember from
watching PBS even as far back as the 1970s. The good thing about this
model is that it allows one to visualize how a mass both distorts space
and moves in response to the distortion caused by another object. But
its goodness as a model of gravity ends there, in part due to
cyberchondriac's astute observation that it makes use of gravity to
explain gravity. Still, the model is not bad because it uses one aspect
of gravity (that it is nearly uniform near the surface of the Earth) to
explain a *different* aspect of gravity (that distortions caused by
multiple objects can interfere with each other and lead to motion).

In reality, it's both space *and* time that are being
distorted.

Not quite. In reality, the best model that we have is general
relativity, according to which both space and time are being distorted.
But this is not to say that space and time are being distorted in
reality, because we will never know for sure what's going on in reality.
That is, a scientific theory (like general relativity) can never be
proved true, though it can be proved false. Who knows? General
relativity might be ruled out by some future experiments and replaced
with a fundamentally different view of gravity.

Comment Re:135 GeV seems very high... (Score 4, Informative) 197

Having a degree in physics means nothing if you didn't do
anything in this branch of physics.

That seems a bit strong. A physics degree does mean that you can
reasonably expect an explanation to be understood without too much
effort on your part.

First off, the electron is not the lightest particle. Strictly
speaking, the electron neutrino weighs in at less than 2.2 eV, where the
electron weighs in at 0.511 MeV. Then you have the tau neutrino, which
weighs in at 15.5 MeV. Then you have the proton, which weighs 938 MeV.
After that we have the tauon, which has a mass of 1.7 GeV. All of which,
so far, are leptons.

I can see where you're going, but you made a careless error. The proton
is not a lepton.

In the standard model, leptons and quarks are fundamental particles.
Leptons and quarks are reflections of each other through a certain
symmetry. But a quark never appears by itself. A quark-antiquark pair
is called a meson (which is a boson because it has whole-integer quantum
spin), and a triplet of quarks, like a proton or neutron, is called a
baryon (which is a fermion because it has half-integer quantum spin). A
hadron is any particle that interacts through the strong force; this
includes mesons and baryons but not leptons.

User Journal

Journal Journal: Karma

Recently my karma changed from negative to neutral, and then to positive.

A long time ago, someone had caused my karma to go negative. Since then, my comments have probably been largely invisible. But a kind soul gave me a boost recently. And then I managed to post something interesting enough to move into positive territory.

It's been a long time, but I'm grateful.

Not that I post very much, but it's been a bit depressing at some low level for a couple of years.

Space

Journal Journal: The Solar Sail Debate

I was too slow to get my two cents together on the great solar sail debate earlier this month. The discussion has been archived, and so I can't post a comment there. I did, however, write up an analysis (HTML) that cleanly shows what's wrong with Gold's basic model. I even treat the relativistic case, all with just a simple collision model stole

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