Please create an account to participate in the Slashdot moderation system


Forgot your password?
Trust the World's Fastest VPN with Your Internet Security & Freedom - A Lifetime Subscription of PureVPN at 88% off. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. ×

Comment Tidal locking question (Score 1) 212

Low mass stars (and this one is very low mass) are dim, so the habitable zone is very close, so tidal effects of the star on the planet are large*, so under normal circumstances the planet will tidally lock to the star, which is not friendly to life. (Although I wouldn't go so far as to say life is impossible on a tidally locked world.)

If the planet has a large enough moon, it will lock to the moon instead, and avoid the star tidal lock (at least for a while.) So I imagine a planet and moon locked to each other and in close orbit around the star. In this case, what will happen to the planet/moon orbit as it gets perturbed by the stellar tides? Will it remain stable, or has the moon only bought me temporary reprieve from stellar tidal lock?

* Back of envelope tidal calculation:
Luminosity of star L proportional to mass of star M to 4th power (roughly)
Goldilocks orbital radius R proportional to sqrt(L), i.e. R propto M^2
Tidal strength T propto M/R^3 (it is derivative of M/R^2), so T propto M/M^6 = 1/M^5. (It is the 1/R^3 which allows a moon to out-tide the star, despite being very much less massive.)
News says this star is 2000 times fainter than the sun, so about 0.15 solar masses
So tidal effects of star on habitable planets is about 13,000 times greater than tidal effect of sun on earth.
The tidal effect of the sun on the earth are small but noticeable - it causes the difference between spring and neap tides.

Comment This would make it the 5th continent (Score 1) 141

If you are claiming that it isn't coastlines and land areas which make continents, but rather regions of continental rock (whether above sea level or not). If this is so, you can no longer justify counting Africa as separate from Eurasia, or North and South America being separate from each other. So you can pick between the traditional 6 continents by land area, or four or five by crustal rock (Eurasia+Africa, Americas, Antarctica, Australia, and Zealandia if you think it is big enough.)

Incidentally, New Zealand may have been almost entirely submerged 24 to 21 million years ago.
I don't know if there were any other major Zealandia land masses at the time.

Comment Coal to gas conversions? (Score 1) 415

"Many older coal plants have been closing in recent years, thanks to stricter air-pollution rules and cheap natural gas."

How often is it economic to do power station coal to gas conversions? Clearly you need to be near a gas pipeline. Can you just replace coal fired boilers with gas fired boilers, or is it more complicated? If instead you're using gas turbines, there is much less commonality between the old and converted power station, and less reason to convert rather than start with a green field.

Comment Re:No (Score 4, Informative) 328

I think everyone (or nearly everyone) should be taught a minimal amount of coding, not so that they can code, but so that they can appreciate what coding can do (and so they can decide whether they are interested in learning more.)

Here is a parable.
Lecturer was approached by Researcher. Researcher was working with DNA sequences and had received a large computer file with many thousands of DNA sequences. These sequences all had a few characters at the beginning and end which were artefacts of the amplification and sequencing process, and needed to be removed before the sequences could be used by the next stage in the process. This was the second such file Researcher had worked with - the previous time, Researcher had spent about a month editing the file in a text editor to remove the surplus characters. Now they dreaded having to do it again, and hoped Lecturer could provide a better way. Lecturer promptly solved the problem in under a minute with a one line Unix command.

Had Researcher had an idea of what programming can do, they'd have sought this help when they received the first file, and saved a month of extreme drudgery. (Incidentally, this really happened, my current boss was Lecturer.)

I present here (not for the first time) the Woodhams Hierarchy of Epistemological Categories:
1) Stuff that you know
2) Stuff that you know where to find out
3) Stuff that you know that somebody knows
3a) Stuff that you know that nobody knows (a category irrelevant to this discussion but important to scientists.)
4) Stuff you know nothing about
(Compare to the Rumsfeld Epistemological Categories.)

In the parable, 'how to best modify these DNA sequences' was initially in category 4 for Researcher, but would have been category 3 if they'd ever done some simple programming. The difference between category 4 and category 3 cost them a month. The difference between category 3 and category 1 cost them perhaps 20 minutes - instead of writing the one-liner themselves, they had to find somebody who could write it for them. This pattern is typical - when considering shifts in categories (from 4 to 3, from 3 to 2, and from 2 to 1) the benefit of shift 4 to 3 is greatest, and the cost (i.e. acquiring the knowledge) is lowest.

To be a functioning person, you need stuff in category 1, but people usually undervalue categories 2 and 3, which can cover very much more knowledge than you can fit in category 1.

Comment What about nausea? (Score 4, Informative) 115

Many people get motion sickness when in a VR with a moving viewpoint. Having your patient suddenly sit up and vomit would probably not be a good idea during surgery. The simplest solution would probably be to test them on the VR first to see if they are nausea-prone, and choose the surgery VR experience based on that.

Comment Missing hypothesis (Score 3, Interesting) 176

Maybe the noble savage really is "serene, peaceful, in tune with nature, never takes more than he gives", precisely because their ancestors learned such a hard lesson and taught their descendants "don't mess up like we did". (I'm not saying it is so, just that it is consistent with the observation of prehistorical extinctions.)

Comment Re:Con? (Score 2) 406

They cheated if they broke the rules. Without knowing in details what the rules were, we can't say whether they cheated.

However we do know that a judge who knew in detail what the rules were required them to return the money. This being a civil case, we don't know if what they did was criminally illegal.

Comment Con? (Score 1) 406

Persuade (someone) to do or believe something by lying to them.
A confidence trick ... is an attempt to defraud a person or group after first gaining their confidence, used in the classical sense of trust.

I don't see where he lied, so I think the word is misapplied. The second definition comes a little bit closer, but casinos are very much aware that gamblers are adversaries, not allies.

Comment Making America great again (Score 4, Insightful) 129

What do people mean when they say "make America great again"? My understanding is that they want a USA which is making new innovative industries, employing lots of people in the USA with high paying jobs, and making profit in the process (the more the better.) Elon Musk is the poster child for doing all of those things - yet many people crying "Make America great again" are trying to tear him down. The kindest explanation is that they are so blinded by ideology that they can't think straight.

Slashdot Top Deals

"Today's robots are very primitive, capable of understanding only a few simple instructions such as 'go left', 'go right', and 'build car'." --John Sladek