Carrock

Enthalpy, you seem to be refuting things I didn't write, partly by agreeing with things I did...

2 hours ago, Enthalpy said:

With metal beams, there would have been even less fire damage.

I ignore why the spires were not built. The towers are obviously meant to carry much more weight - just observe the sections up to the present top. The spires were in the plans in 1160 but abandoned in 1240, I haven't read a reason. With present materials, they would weigh a fraction of what was possible then.

As spires are a relatively low part of the total cost, it's a reasonable speculation that the materials, build quality or foundations were considered inadequate for the extra weight.

5 hours ago, Carrock said:

Very old buildings still in use often are and sometimes have to be somewhat modified over the years, but the default assumption should be that as they still exist the builders were competent.

Thanks for the expansion...

2 hours ago, Enthalpy said:

The very Notre-Dame shows that builders do how they are used to within their time. The construction spanned two centuries (if you allege it's finished without the missing spires) and the style is hybrid, the techniques too. Most other constructions had their plans heavily modified over time, before or after "completion". Check for instance the Stephansdom in Vienna, St Vitus in Prague... about every cathedral

Construction of Notre-Dame (English)
Construction of Notre-Dame (French, other details)
Stephansdom
Saint Vitus in Prague
In Notre-Dame, the transept was added later and their front increased even later, and so on and so forth.

2 hours ago, Enthalpy said:

Don't overestimate neither the knowledge of middle-age architects. Many of their buildings collapsed, others (cathedral in Strasbourg and more) could not be finished because their design was flawed. That some buildings still stand is an achievement, but don't presume present architects would do it worse. Many Parisian buildings date back to 1850-1870

You seem to be suggesting nothing was learned from those failures and the builders of Notre Dame etc were just lucky. Really?

When I referred to builders' competence I was referring to collective competence. This would include judgment of whether many nonstandard constructions were adequate. I still believe modern architects would not do as well as the builders unless you allowed them to use some modern technology e.g. pencil and paper.

I didn't mention architects as they were as rare as hens' teeth...

From https://en.wikipedia.org/wiki/Architect

Quote

Throughout ancient and medieval history, most of the architectural design and construction was carried out by artisans—such as stone masons and carpenters, rising to the role of master builder. Until modern times, there was no clear distinction between architect and engineer.

...

Paper was not used in Europe for drawing until the 15th century but became increasingly available after 1500.

13 hours ago, Enthalpy said:

My proposal for a new roof: aluminium tiles.

Gotta wonder if the next fire will be hot enough to ignite aluminium...

2 hours ago, John Cuthber said:

There is no need for everything to be "modern".

There would have been less damage if the modern (19^th century) tower hadn't collapsed into the building. Often 'obvious' improvements like extra towers etc weren't included because the builders knew that such constructions could overload the building or cause serious damage in a fire etc.

Very old buildings still in use often are and sometimes have to be somewhat modified over the years, but the default assumption should be that as they still exist the builders were competent.

1 hour ago, DrP said:

On 4/18/2019 at 8:51 PM, Airbrush said:

Yes, but old buildings can always be retro-fitted with safety devices.  Why don't they build an ornate tower that is actually a swiveling HOSE, controllable by joystick and camera monitors, that can reach the entire structure?  Any ancient structure can have such a firefighting structure retro-fit, that is hardly noticeable, but blends into the exterior design.   

Do old buildings in the US all have these fitted then or something? 

All the old US buildings have these fitted.

They're not considered cost effective for modern buildings i.e. less than 500 years old.

Also, are you aware of the relationship between the amplitude and the intensity of a sound wave? Hint: they are not directly proportional.

Complementary to studiot's post:

Most metals have a thin layer of oxide which usually prevents any direct metal to metal contact.

If there is any metal to metal contact it's usually a very small area (due to uneven/contaminated surfaces) and any bonds can easily be broken.

I have read that in space, where the above is less significant, accidental welding of two metal surfaces is a significant safety issue.

5 hours ago, John Cuthber said:

Unless they carefully say otherwise, you can assume they are working with aqueous solutions.

23 hours ago, Aidan Bradley said:

"A 1.0 g mixture of magnesium chloride and sodium nitrate is dissolved in water......

An additional hint in the OP.

On 3/28/2019 at 2:59 PM, tjackson2112 said:

And the melt begin, I should have added.  How else could you dump billions of gallons of water in a controlled way onto a dry world like Mars where moisture is needed in any process of terraforming?

If it's possible to get a loosely aggregated large icy body into low orbit, it might be possible to separate it with explosives into sufficiently small fragments to melt during entry. Any larger fragments could similarly be reduced in size.

Very speculative idea, and even if it becomes possible, any miscalculation could be disastrous.

2 hours ago, MigL said:

Sorry Carrock, although your posts 'inspired' my response, it was actually meant for Q-reeus, who is no longer with us.
I apologize for the confusion my lack of specifics caused.

Yours was a good response to my rubbish post.

I misinterpreted the paper, the red mist descended and I pressed 'Submit Reply' without engaging brain...

Old mains clocks, such as mathematic may have, had a synchronous motor and were dependent on mains frequency for accuracy. IIRC they had a tendency not to start, or to run backwards, so they were likely designed to work at lower than normal voltage, so that they'd be reliable at normal voltage.

So the dimmed bulb may be normal, while the clock continued to run on a very low voltage.

21 hours ago, Carrock said:

I suppose on second thoughts that paper is a pretty normal Copenhagen interpretation; it's just the scale of the superposition that's unusual.

I realised I'd got it wrong, too late to edit my OP; I didn't make that clear enough.

Or that I had realised

Quote

Decoherence is caused by the information flowing from the system into its environment and the resulting formation of records of its selected observables in that environment

is consistent with any valid QM interpretation. (The referenced book is behind a paywall; how 'environment' is defined is of course crucial.)

Clarification:

7 hours ago, MigL said:

You fail to realize that these are interpretations.
In that particular paragraph .....

You appear to be referencing an unspecified paragraph from "Hawking, S. W. Particle creation by black holes. Commun. Math. Phys. 43, 199–220 (1975)."

As I didn't quote from it, I don't think a cited reference has much relevance to the quality of the citing article.

8 hours ago, MigL said:

The theory/model is mathematical ( which you seem to abhor );

Don't know where you got that from...

7 hours ago, beecee said:

Eloquently put!

Congratulations on the cheerleading. +1

In summary: nothing in the paper appears to depend on a particular interpretation. I originally thought it did.

I suppose on second thoughts that paper is a pretty normal Copenhagen interpretation; it's just the scale of the superposition that's unusual.

From https://www.nature.com/articles/s41467-019-08426-4

30 minutes ago, beecee said:

Here we consider the decoherence of a “black hole Schrödinger cat”—a non-local superposition of a Schwarzschild black hole in two distinct locations—due to its Hawking radiation. The resulting decoherence rate turns out to be given by a surprisingly simple equation. Moreover, and in contrast to known cases of decoherence, this rate does not involve Planck’s constant ħ.

Another quote from that paper:

Quote

They also present the decoherence by Hawking radiation as something fundamental and unavoidable, just as we do.

Ouch. From a reference from that paper:

Joos, E. et al. Decoherence and the Appearance of a Classical World in Quantum Theory. (Springer, Berlin Heidelberg, 2003).

Quote

Decoherence is caused by the information flowing from the system into its environment and the resulting formation of records of its selected observables in that environment

So a whole paper with quantified maths about an arbitrary split between quantum superposition and a purely classical environment i.e. no superposition of different 'records.'

This would only be valid if the Copenhagen interpretation was a distinct theory rather than an interpretation.

Dubious theory isn't confined to SF speculation section...

The disinformation and ad hominem attacks go on....

5 hours ago, rangerx said:

I'm inclined to think that commissioning a hack for unauthorized access, downloading classified documents and redistributing personal information would disqualify whistle blowing.

More of a criminal matter than a civilly disobedient one. The public interest wasn't served.

Manning initially approached Assange. Whether Assange did anything more with Manning than most investigative journalists (not whistleblowers) would do is very questionable at present. The difficulty for the U.S. was/is finding a charge which would not also apply to a few million other journalists.

The relatives of victims of the war crimes in Iraq and elsewhere who would otherwise never have known what happened likely have a different view on what is in the public interest than you do. Perhaps, like Hillary Clinton, you think the harm he did to the democrats outweighs this?

5 hours ago, rangerx said:

Most whistle blowers aren't disappeared or convicted. They're usually end up losing their job/career or otherwise blackballed in some way.

Chelsea Manning was convicted and had her sentence commuted by Obama.

She's now 'enjoying' her freedom during an indefinite prison sentence, much of her time in solitary confinement.

A somewhat disproportionate sentence for an unnecessary witness?

Quote

While everything she did with WikiLeaks in 2010 came out in her trial, in March she was nevertheless ordered to testify again in front of a grand jury, now known to have been investigating Assange.

Manning, a strong critic of the secret panels often used by prosecutors in high-profile cases, said she objected "strenuously" to the subpoena.

"We've seen this power abused countless times to target political speech," she said, making clear that she would be willing to testify in public.

On March 8, the judge ordered her locked up in an Alexandria, Virginia detention center until she testifies or the grand jury is wound up.

The indictment of Assange -- issued secretly in March 2008 -- would appear to negate the need for her testimony.

Secret justice is often more expedient than disappearing people.

1 hour ago, Sensei said:

If you shoot x-ray photon at oil drop to ionize it, oil drop will be positively charged afterward, and free electron will be ejected.

ps. Sorry for nitpicking..

 

Guess I'll denitpick by appealing to authority...

51 minutes ago, MigL said:

"Never having investigated the experiment", Carrock ?

I assumed your background was Physics.
Millikan oil drop is standard 1st year experiment for Physics.
( at least it used to be 4 decades ago )

I was told about the experiment; I don't recall doing it. And I didn't do the calculations so it still seems improbable.

Sometimes ignorance is worth preserving. I'll keep my vestigial sense of awe unless (improbably) I have to learn the details.

One of my favourites is what used to be called the Millikan oil drop experiment. (It seems Fletcher's contribution was not acknowledged.)

Measure the mass of a negatively charged oil drop by letting it fall at terminal velocity.

Then calculate the charge from the electric field required to provide exactly the upward force required to balance the gravitational force.

The calculated charge is always an integer multiple of the (now known) electron charge.

Never having investigated the experiment, I still have some of my original awe that such a conceptually simple (in hindsight) experiment could measure something as tiny as the electron charge.

10 hours ago, beecee said:

OK, after absorbing the original article, A question has arisen in my mind....If  these events had not have happened, and someone were to ask me what happens when two neutron stars merge/collide, I would have unhesitatingly said that a BH would be formed. So why a Magnetar in the original article? Did they just graze each other, with one spinning faster as a result of meeting? It seems that if two neutron stars were to smash into each other, that any joining of the two would then probably exceed the NDP? Is the answer [as appears likely] dependent on the combined trajectories of their meet up? Probably I would think. Any other thoughts?

Interesting questions.

Before reading the abstracts, I'd have assumed that e.g. two coalescing neutron stars each of 1.1 solar masses (apparently the minimum neutron star mass) would produce a neutron star of at most 2.2 solar masses and definitely not a BH.

However, your first source

Quote

If the neutron-star equation of state is sufficiently stiff (that is, the pressure increases sharply as the density increases), at least some such mergers will leave behind a supramassive or even a stable neutron star that spins rapidly with a strong magnetic field^5,6,7,8 (that is, a magnetar).

hints that if the neutron-star equation of state is not sufficiently stiff transient high pressure may produce a region sufficiently large and dense in the coalescing neutron stars to form a black hole smaller than the usual minimum.

AFAIK all the collisions observed so far have been binaries coalescing where much of the angular momentum ends up in the final neutron star/black hole e.g. one high spin magnetar.

It's possible that collisions between non binary neutron stars etc are common enough for some to be observed eventually. Those seem to me, especially if the collision is nearly head on, to be the best option for producing unusually small black holes.

Any other thoughts?

A few other points worth mentioning.

51 minutes ago, swansont said:

The charges predate his request for asylum. They did not "appear from nowhere"

https://www.telegraph.co.uk/news/worldnews/wikileaks/11681502/Why-is-Julian-Assange-still-inside-the-embassy-of-Ecuador.html

From that reference

Quote

There are no charges against him in the US, although he fears he could be put on trial for espionage.

Yet The Washington Post reported in 2013 that the Justice Department had concluded there was no way it could prosecute him.

.........

WikiLeaks spokesman Kristinn Hrafnsson said that they would not believe any assurances "short of an open, official, formal confirmation that the US government is not going to prosecute WikiLeaks".

The U.K. government is now considering a U.S. extradition request re computer hacking or similar. Maximum jail time would be five years, unless U.K. agrees to other charges after extradition, which is not unlikely.

Chelsea Manning, having had her sentence commuted by Obama, is now back in jail for an indefinite time.

It seems to have been almost forgotten that many instances of torture, murder of civilians and various other war crimes would likely have remained hidden without Manning and Assange. Possibly such crimes are now rarer because of Wikileaks. OTOH the U.S. has stated some people were put in danger by the leaks.

There's a lot I don't like about Assange, but there is so much disinformation around that much of what I believe about him is likely wrong.

(Even the BBC got the reason for extradition wrong.)

6 minutes ago, Strange said:

If the aliens decide to explain the technology, I can imagine several possible results:

1. The scientists / technologists who hear the explanation slap themselves on the forehead, say "of course" and rush out to build their own.
2. The humans would spend months or years trying to understand the advances in science required - mathematicians would struggle to convert the alien notation to something they were familiar with - but after a few years or decades, they would put together their first prototypes.
3. The aliens spend decades providing lectures, explanations, seminars, diagrams, working models, etc. And the human audience just sit there looking blank and going, "Nope. Still not getting it. Can you explain it again from the beginning? Are you sure it isn't magic?" 

3 is definitely the most interesting, especially if they have the same problem when we try to explain e.g. how a bicycle works.

BTW, I couldn't select the numbers in your post. Was that magic, or could I work how you did that if I really tried?

Even earlier computers...

Quote

The period 2700–2300 BC saw the first appearance of the Sumerian abacus.

15 hours ago, wtf said:

16 hours ago, Carrock said:

Can you [beecee] tell me which part of "infinity for five year olds," showing that there's twice as many integers as there are integers, or as many even numbers as integers or whatever, is beyond your comprehension?

Or, as you likely meant, beyond the comprehension of a five year old?

As Wittgenstein might have said: Whereof one cannot speak without snark; one must thereof put a sock in it. I shall heed his advice.

Uh ... which is it? Are there twice as many or the same as? Perhaps it's beyond YOUR comprehension. Damn, the snark leaked out anyway. Only happened because I read your post a second time and realized you yourself are fuzzy on the example.

 

Did you read this earlier post, referenced in the post you quoted?[pedantic snark] Nothing in the rules against using onsite references.[/pedantic snark]

On 3/21/2019 at 8:57 AM, Carrock said:

I'll bite... assuming she's learned her two times tables and how to divide/multiply by two..

Ask her what is the 2^nd even number.

Then 4^th, 5^th etc and ask her if she sees a pattern....

If she does, ask what is the 43^rd even number, reassuring her that doing it the easy way without counting each number isn't cheating, but higher maths. Do a few more calculations until she's comfortable with the idea.

Then ask her for the biggest 'real' whole number she can think of. And of course the [biggest 'real' whole number she can think of]^th even number.

Shouldn't take her very long to realise* that the set of positive integers can be placed in one to one correspondence with the set of positive even integers.

And so on....

 

*informally

Anything fuzzy here?

The later post was inspired by a third party story of [appeal to authority] R. Feynman [/appeal to authority] showing a child 'there are more numbers than there are numbers.'

I think children are as good as adults at learning something new, especially when, as I was careful to exemplify, they already have all the basic maths they need to understand a new concept. It takes a certain perverse sort of ignorance/laziness to teach children infinity is 'difficult,' compared to e.g. division.

18 minutes ago, beecee said:

The application of infinity is difficult to comprehend.

Can you tell me which part of "infinity for five year olds," showing that there's twice as many integers as there are integers, or as many even numbers as integers or whatever, is beyond your comprehension?

Or, as you likely meant, beyond the comprehension of a five year old?

14 hours ago, wtf said:

...how to explain philosophical mathematical infinity to a five year old....

I'll bite... assuming she's learned her two times tables and how to divide/multiply by two..

Ask her what is the 2^nd even number.

Then 4^th, 5^th etc and ask her if she sees a pattern....

If she does, ask what is the 43^rd even number, reassuring her that doing it the easy way without counting each number isn't cheating, but higher maths. Do a few more calculations until she's comfortable with the idea.

Then ask her for the biggest 'real' whole number she can think of. And of course the [biggest 'real' whole number she can think of]^th even number.

Shouldn't take her very long to realise* that the set of positive integers can be placed in one to one correspondence with the set of positive even integers.

And so on....

*informally

53 minutes ago, Vexen said:

What makes Scientology teachings false?

L. Ron Hubbard's science fiction wasn't worth reading.

From what little I know of them, the secrets of the religion he created aren't worth paying for either.

I suppose his religion is as true as any, but sillier than most.

21 minutes ago, Strange said:

Famously (and tangentially again) Lemaitre and Hoyle were very close friends. I'm sure they had some "interesting" conversations about their different views of cosmology. (Of course, for a long time there was not overwhelming evidence on either side.)

Tangentially again, Einstein came up with his own Steady State cosmology, probably just before he abandoned the idea of a cosmological constant. He didn't think the concept worthy of publication.

From A new perspective on steady-state cosmology: from Einstein to Hoyle

Quote

Indeed, an expanding cosmos in which the density of matter remains unchanged seems a natural successor to Einstein’s static model of 1917, at least from a philosophical point of view.
However, such a steady-state universe demands a continuous creation of matter and, as Einstein discovered in this manuscript, a successful model of the latter process was not possible without some amendment to the field equations.

This is consistent with Einstein's 1952 statement

Quote

The cosmological speculations of Mr Hoyle, which presume the creation of atoms from empty space, are in my view much too poorly grounded to be taken seriously.

29 minutes ago, Phi for All said:

The problem here is that it snaps if stretched too quickly, such as in the case of a seat belt in a collision. It would make a great bumper though, wouldn't it? Or boxing gloves?

I was rather intending a fun/annoying quick answer.

I wouldn't be very keen on any seat belt that went rigid just when I wanted it to spread out stresses...

It does have lots of potential uses such as you've suggested. It's 'only' a matter of engineering.

My favourite (Daedalus in New Scientist) was as the paving for (very) short stay parking.