Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?

Slashdot videos: Now with more Slashdot!

  • View

  • Discuss

  • Share

We've improved Slashdot's video section; now you can view our video interviews, product close-ups and site visits with all the usual Slashdot options to comment, share, etc. No more walled garden! It's a work in progress -- we hope you'll check it out (Learn more about the recent updates).


Comment: You miss the center by how much? [Re:Kinda notnews (Score 2) 121

by Geoffrey.landis (#49094271) Attached to: The Science of a Bottomless Pit

OK I created the following Matlab code:


The plot isn't very impressive. It looks like a line straight through the center. The min radius is 114m so basically over 6500m drop the center moves about 114 m.

That doesn't seem right. You are doing the calculation in the rotating coordinate system of the Earth?

Equatorial rotational velocity of the Earth is 465 m/s. The center of the Earth is stationary in the rotating coordinate system, so over a 22 minute drop, the lateral displacement should be 614 kilometers. That's not the distance by which you miss the center, since as you deviate from the initial radial line the gravity vector changes direction, but the effect of that will be small until you get to distances that start to be comparable to 10% of the Earth's radius, so it should be close to the miss distance.

It's a non-Keplerian orbit (even in the non-rotating frame), so you don't come back to the same place you started.

Comment: Non Keplerian [Re:Kinda notnews] (Score 4, Informative) 121

by Geoffrey.landis (#49094197) Attached to: The Science of a Bottomless Pit

Mathematically it's an example of a degenerate orbit with one zero semi-axis, and the orbital period can be simply calculated from Kepler's laws.

No, it can't; it's not a Keplerian problem. You could calculate the period using Kepler's laws if the Earth were a point mass. But it's not. You could calculate the period using the Brachistochrone calculation if the Earth were a uniform sphere. But it's not. The Earth is layered, with the density changing as you go closer to the center. Only way to solve the problem correctly is numerical integration.

(I'd actually be interested in seeing the calculation done in the article.)

Comment: Revised- headlne and the text say different things (Score 1) 114

Actually, I should modify my comment. The headline does say a different thing from the summary, but the actual article does in fact go on to give some reasonable evidence that connecting the group to the NSA. So, "tied to NSA" is an accurate summary, although with the caveat "tied to" is words that "stop short" of saying that it actually is the NSA.

Comment: The headlne and the text say different things (Score 2) 114

The headlne says different things than the text and the original article.

The headline says that they "were found"... but they weren't.

The headline that they are "tied to NSA"... but TFA says that "researchers stopped short of saying Equation Group was the handiwork of the NSA."

Comment: Where, when, what-- (Score 2) 397

by Geoffrey.landis (#48918121) Attached to: "Mammoth Snow Storm" Underwhelms

In central mass north of Worcester I have gotten 3 feet and it is continuing to fall. There is so much snow I have no where to put it.

The inaccuracy in the prediction seems to be not about the magnitude of the storm, but about how far south it would hit (and, in particular, whether it would hit New York City).

Nice discussion of the various models' predictions here: http://fivethirtyeight.com/dat...

Comment: Re: Maybe Einstein gets the last laugh afterall? (Score 1) 81

by Geoffrey.landis (#48884697) Attached to: Quantum Computing Without Qubits

Einstein made essential contributions to quantum mechanics, and yet he objected to many of its implications. His objections have been shown to be wrong.

To the contrary, his "objections" consisted of pointed out consequences of quantum mechanics that seemed paradoxical, but, as experiment showed much later, were completely real. Einstein is the "E" in "EPR", and the implications of the EPR paper pretty much is the foundation of quantum computing.

Comment: Impossible to change (Score 3, Insightful) 360

by Geoffrey.landis (#48836561) Attached to: NASA, NOAA: 2014 Was the Warmest Year In the Modern Record

I'd say that instead of falsifying data NASA and NOAA need to start being honest.

The difficulty is that once you decide that you can selectively ignore facts because of a huge conspiracy to falsify data, it becomes impossible for any amount of information to ever change your mind. So, the NASA data is falsified? And, the NOAA data, that's falsified too. And the University of East Anglia, of course. And the Berkeley data-- that was done specifically to address the problems people had with the NASA and NOAA data-- http://berkeleyearth.org/ That's faked too.? How about the Japanese data? http://ds.data.jma.go.jp/tcc/t... Also faked? The Australians-- fake too?

Once you conclude everything that disagrees with you is fake, your opinion is incontrovertible-- since nobody can confront it.

Comment: Re:call me skeptical (Score 1) 360

by Geoffrey.landis (#48836445) Attached to: NASA, NOAA: 2014 Was the Warmest Year In the Modern Record

Right; there are both positive and negative feedbacks.

If you really want to know about the various climate feedbacks, try the summary in section 8.6 ("Climate sensitivity and feedbacks") of the the IPCC Fourth Assessment Report: https://www.ipcc-wg1.unibe.ch/... (the section starts on page 629)

Comment: Re:call me skeptical (Score 1) 360

by Geoffrey.landis (#48834827) Attached to: NASA, NOAA: 2014 Was the Warmest Year In the Modern Record

Im saying that 20 of those 30 years didnt see any warming.

If you want to claim this (nonsense), you should at least back it up with some links, so we can add the involved web sites to our kill files.

you would ignore data that contradicts your beliefs???

It would be helpful here if everybody pointed to a common data set, so we all knew that we were talking about the same thing.

Here's the NASA-NOAA, showing NOAA (in blue) and NASA (in red) 's values for average temperature since 1880: http://www.wired.com/wp-conten...

You can see the "hiatus" in the far right of the graph: the curve to right of about 2000. If you blow up just this portion of the graph, and leave out everything to the right of 1998, you can make a graph which makes it appear that global warming has stopped.

So: the deniers look at this graph and say "warming stopped in 2002". People skeptical of the deniers say "There's a clear upward trend with random fluctuations; there's nothing statistically significant in the data after 2002; it's well within the range of variation in the record."

Or, you can say "There's a clear long-term rise. However, superimposed on that long-term trend are shorter term variations; these shorter term variations are also data, and the study of the causes of these variations may be a valuable subject for research."

A man is not complete until he is married -- then he is finished.