Carrock
-
Posts
601 -
Joined
-
Last visited
-
Days Won
2
Content Type
Profiles
Forums
Events
Posts posted by Carrock
-
-
A quote from 3 years ago after the first fatal crash.. https://www.bbc.co.uk/news/technology-36680043
QuoteThe Autopilot function was introduced by Tesla in October last year. In a conference call, the firm's enigmatic chief executive Elon Musk urged caution in using the technology.
"The driver cannot abdicate responsibility," he said.
A 2018 crash https://www.bbc.co.uk/news/technology-49594260
QuoteThe design of Tesla's Autopilot system and "driver inattention" led to a crash in 2018, according to a US National Transportation Safety Board report.
It said Tesla's semi-autonomous driving system "permitted driver disengagement from the driving task", resulting in the crash, on a California motorway.
Tesla says Autopilot "requires active driver supervision" and drivers should keep their hands on the steering wheel.
On 10/4/2019 at 11:47 PM, Endy0816 said:Obtain human input on how to handle an unusual situation, while otherwise remaining on autopilot.
QuoteIn a statement, Tesla said it appeared the Model S car was unable to recognise "the white side of the tractor trailer against a brightly lit sky" that had driven across the car's path.
When Elon Musk says "For maximum safety, the driver must abdicate responsibility," autopilot cars may be safer than human driven cars.
0 -
1
-
26 minutes ago, John Cuthber said:
I'm fifty-something man and , if I turn up in A&E with chest pains I expect to jump the queue in a way that my hypothetical twin sister wouldn't.
I'm not saying that's good or right; I'm saying it's what happens.Not in my one-off experience.
I took a neighbour in her 20s complaining of chest pains to A&E and she jumped the queue as soon as the triage nurse heard the magic words 'chest pain.' (It was 'just' asthma + panic attack.)
As unexplained chest pain is always(?) treated as time critical and I'd be surprised if any A&E would normally spend time triaging such patients.
0 -
5 hours ago, westom said:
All wire has impedance. So a voltage difference always exists with any current in a wire.
Where is the voltage difference in a transformer secondary which consists of one continuous loop i.e. short circuited output winding?
2 -
Even supposedly objective tests like DNA have problems with "But force women out of their jobs for stating that sex is real?"
or remove children if DNA 'proves' a woman is not the mother of her supposed children?
From https://en.wikipedia.org/wiki/Lydia_Fairchild
QuoteFairchild stood accused of fraud by either claiming benefits for other people's children, or taking part in a surrogacy scam, and records of her prior births were put similarly in doubt. Prosecutors called for her two children to be taken away from her, believing them not to be hers. As time came for her to give birth to her third child, the judge ordered that an observer be present at the birth, ensure that blood samples were immediately taken from both the child and Fairchild, and be available to testify. Two weeks later, DNA tests seemed to indicate that she was also not the mother of that child....
[eventually]
They also found that, although the DNA in Fairchild's skin and hair did not match her children's, the DNA from a cervical smear test did match. Fairchild was carrying two different sets of DNA, the defining characteristic of chimerism.
A very intrusive example of "guilty until proved innocent."
Fiascos like this suggest that human chimerism is much more common than used to be believed. No doubt some murderers have escaped justice because DNA proved them innocent.
I couldn't find any male/female chimera being banned from all bathrooms but give it time.....
2 -
https://study.com/academy/lesson/electroscope-experiment.html
19 hours ago, studiot said:The bits that move apart are metal foil, traditionally gold leaf, but they can be fashioned from kitchen foil.
The weight per unit area of foil is important as it has to be raised against gravity. Gold is the most malleable element and can be beaten into sheets less than 1000 atoms thick. Good luck trying that with kitchen foil.
You can buy about 1.8ft2 of 0.12 micron gold leaf for $8.12 but probably best to find someone who uses it and pay $0.20 for an offcut.
0 -
3 hours ago, D_A said:
the rules of the (rigid) set theory are no longer applicable (at least according to my logical thinking).
The librarian is free to include a reference in the catalogue (of catalogues which don't include themselves) to itself, for instance.
Well yes, but a librarian would want accurate descriptions.
The catalogue title "A catalogue of catalogues which don't include themselves (also including exactly one catalogue which does include itself)" is accurate(ish) but who would want to use it without an explanation of why that one catalogue is included since it obviously isn't quite kosher?
The librarian would soon become an expert on explaining Russell's paradox.
If there were many realistic real-life problems involving Russell's paradox the paradox would have been discovered long before Russell.
Finding a different solution here is simple but doesn't negate the inability to create that catalogue of catalogues which don't include themselves.
QuoteThe gist of my argument is that (I feel) your example example is not a fair real-life implementation of Russel's paradox.
OK.
QuoteP.S.
I didn't understand the last part of your post: "* and will learn from SF if my understanding is inadequate."
Simply that if I got it wrong a science forums member would likely correct it so that errors wouldn't be perpetuated and I'd learn.
0 -
A non mathematical example from memory (I remember better doing it this way than copy and paste*):
You have a very well organised library with catalogues which collectively reference all the books. Naturally(?) each catalogue is stored according to its own reference as listed in itself. If a catalogue has no reference to itself in its list it is stored in a random location as it can't be very important.
A new librarian is rather irritated to find that some catalogues don't reference themselves; he doesn't like having to search through the entire library for an obscure catalogue.
Solution: create a catalogue of catalogues which don't include themselves in their list. Keep those catalogues in the locations referenced in this catalogue.
Include a reference in this catalogue to itself so it can be stored in a definite location. Oops, you can't since you're creating a catalogue of catalogues which don't include themselves....
So don't include a reference in this catalogue to itself; then you have to include a reference in this catalogue to itself since it's a catalogue of catalogues which don't include themselves....
So this simple, practical solution to this cataloguing problem is impossible because of Russel's paradox.
A couple of things which occurred to me as I was writing:
Perhaps this is related to the problem of finding a catalogue of references to books if you (and the librarian) don't know such a catalogue exists.
Or a more practical problem which often irritates me: I find an interesting old article and it doesn't reference any later articles which include references to it.
* and will learn from SF if my understanding is inadequate.
0 -
Just a point that doesn't seem to be getting much attention.
Trump didn't 'just' delay payment to Ukraine, he ensured that he could never order some of the money paid because the delay had been too long.
If democrats had joined republicans in support of POTUS' actions and opposed a continuing resolution which allowed the payment of all the money, Trump would have succeeded in his 'no quid pro quo' punishment of Ukraine for not announcing new 2016/Biden investigations.
QuoteWASHINGTON―The U.S. House on Thursday passed legislation to make sure Ukraine can spend $250 million in military aid after White House delayed it this summer.
The language was among provisions tacked to a continuing resolution to avoid a government shutdown through Nov. 21 to buy more time for Congress’s spending negotiations.....
The CR passed the House with a bipartisan 301-123, though one notable “no” was House Armed Services Committee ranking member Mac Thornberry, R-Texas, who said it brakes the budget deal’s promise of “stable and predictable funding” for the military.
“We cannot ask the troops once again to pay for Congress’s inability to get our work done, or hold them hostage to either party’s partisan desires,” Thornberry said.
Is Mac Thornberry referring to Congress and the Senate's failure to remove Trump from office before he could block the Ukraine money?
0 -
On 12/7/2019 at 12:42 AM, John Cuthber said:
Currently "Boxing"- by the Queensbury rules" is lawful and knuckle fighting is not.
I didn't know knuckle fighting was actually illegal.
My limited understanding is that bare knuckle fighting usually causes bleeding and may break facial bones, while using (weighted?) gloves protects the hands and causes little visible injury but far more brain damage.
QuoteThe record for the longest bare-knuckle fight is listed as 6 hours and 15 minutes for a match between James Kelly and Jonathan Smith, fought near Fiery Creek, Victoria, Australia, on December 3, 1855, when Smith gave in after 17 rounds.
Presumably gloves facilitate knockouts...
I wouldn't necessarily ban boxing as it's no worse than some other sports, but if boxing gloves were banned, I suspect a lot of people would be upset at seeing the resulting less serious but more visible injuries.
0 -
2 hours ago, Elite Engineer said:
"With a five-year, $875,000 grant from the National Institutes of Health’s National Center for Complementary and Alternative Medicine."
Does that mean he may have done this study just to appease his funders? Is this a common occurence in academic research?
Your unattributed quote is from a blog written by a Psychiatric Nurse Practitioner and posted by Janet. Not necessarily a reliable source.
X-posted : Charony may have found a different reference.
Edit: many different possible sources, but not, it seems, your original references.
0 -
9 hours ago, Elite Engineer said:
Granted this study is from 2008, and there were no further investigations, I've received some flak from my pseudoscience friends for not giving credit to the findings.
The story explains how bioengineer, Tom Skalak at University of VA may have discovered how magnets may reduce swelling. At first I immediately assumed quackery,
but through reading the study I can't explain any mechanisms against the findings or find anything inherently wrong with the study.I can't see magnet therapy being a serious medical treatment. It's concerning, especially for pro-magnet therapy quacks using this to solidify their position.
Study: https://www.physiology.org/doi/full/10.1152/japplphysiol.01133.2006
Study summary: https://news.virginia.edu/content/biomedical-engineering-study-demonstrates-healing-value-magnets
~ee
From https://www.physiology.org/doi/full/10.1152/japplphysiol.01133.2006
QuoteThe costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
That's the only occurrence I could find of “advertisement” in the reference.
From https://news.virginia.edu/content/biomedical-engineering-study-demonstrates-healing-value-magnets
Quote“We now hope to implement a series of steps, including private investment partners and eventually a major corporate partner, to realize these very widespread applications that will make a positive difference for human health,” says Skalak.
If that doesn't convince your pseudoscience friends I doubt any actual science will either.
0 -
1 hour ago, Danijel Gorupec said:
Therefore, the thermal motion cannot excite an electron in a hydrogen atom from 1S to 2S, but it should be able to flip-flop its spin easily. Is this happening in a real gas? (I guess it might be happening in monatomic hydrogen, but not sure about H2 - probably spin cannot be flipped in H2?)
H spins can normally be easily flipped:
Isospin monatomic hydrogen is interesting and unique in that two atoms cannot combine into H2 since with isospin electrons that combination is energetically unfavourable due to Pauli exclusion.
Let it warm up a little and some spins will be thermally flipped; heterospin H atoms will combine into H2 with enormous energy release...
H2 atoms have no net spin so spin can't be flipped.
Offtopic, liquid isospin monatomic hydrogen is so chemically unreactive that it is supposed (unlike helium) to be impossible to freeze.
Multielectron atoms which would normally be diatomic can't be made stable in this way. e.g. isospin fluorine atoms would have plenty of opposite spin electrons for interatomic interactions.
I read (most of) that in Scientific American years ago and haven't been able to find a good reference since, but it all seems very plausible.....
An earlier Eagle comic had a more limited discussion, with Dan Dare accidentally blowing up a few spaceships, which inspired my interest.
1 -
As all I had to go on with Cuthber was 'you are wrong' I attempted to concentrate on the thing I felt sure was correct, the inability of a Faraday cage to prevent an applied D.C. voltage from appearing on its inner conductive surfaces. The voltage etc of any insulated object in the cage is irrelevant.
Against John Cuthber any hint I might have made a mistake elsewhere (as I realised I had after my first post or two - I should have only mentioned voltage, not fields) would be a rhetorical blunder. The Cuthber/Carrock/Swansont part of this thread is a rhetorical debate, not physics.
I'm not sure of the etiquette of quoting someone who changes the meaning when he quotes himself
19 hours ago, John Cuthber said:Still wrong.a Faraday cage only blocks changing fieldsso I'll leave this quote as John Cuthber wrote it save with the original struck out.
I was not surprised John Cuthber did not specifically say I was wrong on any of the issues you mentioned as I have learned his authority is such that his opinions are not open to challenge and I was not going to mention anything more about those issues.
1 hour ago, swansont said:A voltage is not a field, so there’s an issue with this, but saying that a faraday cage only blocks AC is wrong.
The field inside a conducting sphere depends only on the charge inside the sphere. Not the outside field. IOW, it blocks DC as well.
Googling on ‘field inside conductor’ should give you many options for confirmation and explanation.
'A voltage is not a field, so there’s an issue with this'
Not the outside field. IOW, it blocks DC as well.'
So the OP should have asked about fields and currents, not voltage as there’s an issue with this./s
I note you twice mention current being blocked but not voltage. The clear implication is that John Cuthber is right with his deniable claim that e.g. constant voltage is blocked from the (conductive) inside of a Faraday cage.
'The field inside a conducting sphere depends only on the charge inside the sphere. Not the outside field. IOW, it blocks DC as well.'
A bit ambiguous. Anything non conductive inside the sphere blocks D.C.. If there's a constant voltage across the sphere I'd expect some direct current on the inner conductive surface of the sphere, dependent on the magnitude of the internal field. I don't see how the internal field would prevent such current flow.
Your (correct) selective facts are much more effective than Cuthber's empty rhetoric....
You can ignore my report of Cuthber's last post as it was clearly pointless.
My rhetorical skills are clearly inadequate for this forum so I'm taking an indefinite sabbatical.
+1 to Cuthber and you for his win.
0 -
3 hours ago, John Cuthber said:
Still wrong.
OK. I looked at a few of your posts and I finally get it.
Anyone who begins a sentence with
QuoteAt the risk of seeming smug, have a look at my post-count and status as a resident expert...
is immune to criticism.
0 -
1 hour ago, John Cuthber said:
Does wiki say this
a Faraday cage only blocks changing fields, not constant voltage
?
No.
Does wiki say this
a Faraday cage blocks changing fields, and constant voltage
?
No.
I'm not familiar with the concept of blocking/not blocking constant voltage in a conductor. I can live without this knowledge.
Does wiki say this?
QuoteDue to [electrostatic] induction, the electrostatic potential (voltage) is constant at any point throughout a conductor.
Yes.
Fun/scary video. You can see the arcing at about 16s as the linesmen connect themselves and the helicopter to the live high voltage line.
As the linesmen are wearing Faraday cages and the frequency (60Hz) is too low for conditions inside the cages to differ much from D.C., I presume you claim the voltage inside their cages is pretty near zero.
Ask one of them to drop an insulated wire from inside her cage to you on the ground. Good luck persuading her.
Linesmen are so conservative and overcautious that not one living linesman has ever tried this experiment.
Three posts in this thread and you've provided no useful information. Why bother?
0 -
8 minutes ago, Carrock said:
No.
In the spirit of this site, do not provide the correct answer.
7 minutes ago, John Cuthber said:Is that why you made that incorrect assertion?
I should have known you'd take me literally.
Will you edit Wikipedia's incorrect assertions?
0 -
22 minutes ago, John Cuthber said:
Would you like another guess?
No.
In the spirit of this site, do not provide the correct answer.
0 -
2 hours ago, Bobabuilder said:
If you had a square faraday cage grounded at the bottom and wanted to "add 5000 volts" is only instruction I saw. How would you go about that?
I only heard that 5000 volts were added to the exterior of the faraday cage. What would be the simple and cheap ways to add 5000 volts to the exterior of a Faraday cage for fun or folly?As a Faraday cage only blocks changing fields, not constant voltage, what is the point?
Why not just apply the voltage to a wire or capacitor? That is, er, potentially just as lethal.
0 -
In the good old days, someone talking with an object as though it was a person would risk being tried as a witch.
Slightly more seriously, anyone who doesn't use Siri and completes the questionnaire is lying, which may devalue your results slightly......
0 -
7 hours ago, rutholearywalker said:
.... They credited to a documentary called "The Memory of Water" .....
Probably they were thinking of this:
https://en.wikipedia.org/wiki/Water_memory
IMO this is a classic example of research which cannot or should not be reproduced.
0 -
test
in The Sandbox
Test of Mathpix Snipping Tool...
Select a partial screenshot, paste from clipboard....
From my last post here
S=N k\left(\ln \left(\frac{V_{x}}{N}\left(\frac{4 \pi m U}{3 N h^{2}}\right)^{\frac{3}{2}}\right)+\frac{5}{2}\right) ie.
[math]S=N k\left(\ln \left(\frac{V_{x}}{N}\left(\frac{4 \pi m U}{3 N h^{2}}\right)^{\frac{3}{2}}\right)+\frac{5}{2}\right)[/math]
From this image at https://www.scienceforums.net/topic/117535-probability-interpretation/
[math]\begin{array}{l}{P_{1}\left(E_{1}\right)=\left|\left\langle\phi_{1} | \psi\right\rangle\right|^{2}=\frac{3}{5}} \\ {P_{3}\left(E_{3}\right)=\left|\left\langle\phi_{1} | \psi\right\rangle\right|^{2}=\frac{3}{10}}\end{array}[/math] and
[math]\begin{array}{l}{\text { Why not }} \\ {P_{1}\left(E_{1}\right)=\left|\left\langle\phi_{1} | \phi_{1}\right\rangle\right|^{2}=?}\end{array}[/math]
Pretty good for free software...
0 -
On 5/22/2019 at 1:01 PM, studiot said:
However this system is not in Thermodynamic equilibrium.
Classical neither a pressure (state variable) nor a temperature (state variable) can be defined for this system.
This is because pressure and temperature are intensive properties.If you think this can be done please indicate how since the values must include those of chamber B.
Yes a volume (state variable) can be defined since it is an extensive property.
I regard this as a definition issue. I had assumed that, as in many other fields, thermodynamics could have two or more subsystems comprising one system, but all I could find was systems.
From https://en.wikipedia.org/wiki/Thermodynamic_system
QuoteWhen the state of its content varies in space, the system can be considered as many systems located next to each other, each being a different thermodynamical system.
I'll refer to your diagram and labelling to avoid confusion.
The system A (i.e. the contents of chamber A) has a volume of x cubic units.
The system B (i.e. the contents of chamber B) has a volume of y-x cubic units.
The system C, which is the contents of chamber A plus the contents of chamber B, has a volume of y cubic units.
On 5/23/2019 at 2:03 PM, studiot said:You can also obtain your expression of entropy change using statistical mechanics.
System A contains ideal gas in equilibrium at a temperature [math]T= \frac {2U}{ 3Nk}[/math].
System B is a vacuum.
Just before the start of my scenario the barrier between system A and system B is almost instantaneously removed and taken outside both systems with no significant effect (at that instant) on any of the three systems. More plausible scenarios for this action can be devised. Classically, such things can be done with an arbitrarily small effect on the system.
Without the barrier, at the start of my scenario, system A, still instantaneously in equilibrium, has entropy [math]\displaystyle S = Nk \Bigg(\ln\bigg(\frac{V_x}{N}\Big(\frac{4 \pi mU}{3Nh^2}\Big)^\frac{3}{2}\bigg)+\frac{5}{2}\Bigg)[/math]
System B has entropy [math]0\frac{J}{K}[/math].
On 5/22/2019 at 1:01 PM, studiot said:Yes a volume (state variable) can be defined since it is an extensive property.
As entropy is an extensive property, the entropy of System C is the sum of the entropies of system A and system B. Do you agree?
Ignoring intermediate steps for now, system C eventually reaches thermal equilibrium.
Its entropy is [math]\displaystyle S = Nk \Bigg(\ln\bigg(\frac{V_y}{N}\Big(\frac{4 \pi mU}{3Nh^2}\Big)^\frac{3}{2}\bigg)+\frac{5}{2}\Bigg)[/math]
The change in entropy is [math]\Delta S = nK \ln\big(\frac {y}{x}\big) [/math]
Its temperature is the same as system A's original temperature i.e. [math]T= \frac {2U}{ 3Nk}[/math], since neither U nor N has changed. No net work has been done.
Intermediate steps:
On 5/19/2019 at 12:11 PM, studiot said:In order to calculate the entropy change for an irreversible path we must find an alternative reversible method of going from state A to state B and then use this to calculate the entropy change.
For any completely isolated system we are restricted to adiabatic processes since no heat can either enter or leave the sytem.For a reversible process in any such system dq=0, hence ΔS is also zero, which means that S is a constant.
Thus if one part of the system increases in entropy another part must decrease by the same amount.
dU = T dS - P dV from http://www.splung.com/content/sid/6/page/secondlaw
and
On 5/23/2019 at 2:37 PM, studiot said:There can be entropy changes, but not in an isolated [system].
You seem to be saying that if e.g. the left wall of the chamber was rigid, adiabatic and movable, entropy increase would happen since compressing the gas from volume y back down to volume x would be possible i.e. reversing the process; if the left wall is not movable the expansion process is IMO unchanged but entropy cannot increase since the process is irreversible....
From your source http://www.splung.com/content/sid/6/page/secondlaw
QuoteThis defines entropy as a mathematical construct which only remains constant in a perfectly efficient (but hypothetical) closed thermodynamic cycle.
i.e. since my example is neither perfectly efficient at producing work nor a closed thermodynamic cycle entropy increases.
IMO some of the above quotes are inconsistent with this:
On 5/20/2019 at 12:00 PM, studiot said:Entropy is a measure of an observational truth, not the other way round.
I'm not sure if all these are your views or partly representation of Timo's views.
I'm avoiding quoting Timo since we seem to agree with him but draw different conclusions.
On 5/21/2019 at 8:36 PM, studiot said:All states are "equilibrium states".
A condition of non equilibrium is not defined/definable.
This arises because the full description of a state comprises a list of the values of all state variables, each of which which must by definition represent the entire system.
The above quote is arguably inconsistent with
On 5/22/2019 at 1:01 PM, studiot said:In this case the evolved gas 'pushes back' some of the atmosphere and some volume is incorporated in the system.
Work is done and needs to be considered in the energy balance of the system.
I took that a bit casually; of course the gas cooling was not work. All work done ends up becoming heat as the system approaches equilibrium.
In short, the system evolution is not in practice describable with any accuracy but the entropy increases monotonically from the initial state to the final equilibrium state.
More I could say but not now...
0 -
test
in The Sandbox
inline [math]\mathrm{[math][/math]}[/math] test
newline
[math]\displaystyle S = Nk \Bigg(\ln\bigg(\frac{V_x}{N}\Big(\frac{4 \pi mU}{3Nh^2}\Big)^\frac{3}{2}\bigg)+\frac{5}{2}\Bigg)[/math]
newline
[math]\Delta S = Nk \ln (\frac{y}{x}) [/math]
[math]\displaystyle \Delta S = Nk \ln\big(\frac {y}{x}\big)[/math]
0
Remote car steering legalization
in Politics
Posted
Again from the Sept 2019 report https://www.bbc.co.uk/news/technology-49594260 ....
The AI detects the gap several hundred milliseconds to seconds faster than the human driver could have (maybe) and initiates acceleration faster than a human idiot could do. At such a time even a human idiot would likely be concentrating sufficiently to notice a fire engine in front of him, panic, and slam on the brakes or swerve without calmly and dispassionately analysing the situation first.
My experience with AI is decades out of date, but calmly and dispassionately processing the sudden detection of an object just where human experience would suggest it might be, deciding it's serious enough to require braking or swerving, detecting its size and (zero) speed etc and deciding what to do in 0.49 seconds is a big challenge.
AI is great for very rapid response to predictable problems but when it comes to intelligent response to the unexpected, I prefer human parallel processing with billions of years of hardware and firmware development.
It's clear that 30mph is far too fast for safe AI cars.
For now a partial restoration of the Locomotive Act 1861 might be adequate for P.R. and safety.