Charles 3781

58 minutes ago, zapatos said:

I'm voting for appallingly cynical. Just because you feel that way doesn't mean the rest of us do.

Everyone feels that way really.  It's just that most people don't like to display it.  That's understandable.  And not at all a bad thing.  What would happen to families, and society,  and civilisation, if we all displayed the truth to each other all the time.  We'd be mere inconsiderate animals.

The uniqueness of humans is precisely our capacity to lie about our true feelings, in order not to hurt others.

When you have a bath, you  just turn the taps on and the water comes out under mains-pressure to fill up the bath. Couldn't this same principle be applied to flushing a toilet?  

On 9/20/2020 at 9:46 PM, MigL said:

Maybe you should have treated your kids better, Charles.

Would it matter how well a father treated his kids?

Surely the kids' thoughts, on hearing of the paternal demise, will spring immediately to the question: "How much has he left us in his Will?" 

Of course, the kids will exhibit the expected, culturally appropriate  signals of grieving and mourning,  at the Funeral.  But once this ceremony has been accomplished to satisfaction, the  most important business will be attended to:  "The Reading of the Will".    Hasn't it always been that way,  it's just human nature.  Or am I being appallingly cynical?

1 hour ago, geordief said:

Are there other scenarios in Newtonian physics where a separation velocity  is calculated to be able to increase without a limit?

Newton didn't set a limit to velocity, as you know.   It was Einstein who claimed there is a  limit to velocity, which is  - the velocity of "light" in empty space.

Einstein's claim doesn't seem to have been verified by any practical experiments.  Such as firing a 10, 000 stage rocket into space, then seeing whether the final stage eventually goes faster than light. These experiments have not been attempted because the theory claims they can't work.

Doesn't it remind you of similar claims made in the past, about the impossibility of heavier-than-air flying machines?  Theory said they couldn't work.  But they do.

On 9/10/2020 at 4:37 AM, pzkpfw said:

Absolutely. When I croak, my kids will hopefully remember me a while. ... but they are unlikely to know if my last thoughts were of heaven, hell, or pizza. (And I won't behaving any more thoughts!)

Your kids won't give a stuff about your dying thoughts. They'll want to know:  "How much money do we get from his croaking".

I wouldn't get too excited about marginal instrument readings from a distant planet such as Venus.

This has happened before, in the case of the similarly distant planet Mars.  You know what I mean - the "canals".

 Can anyone come on here, a serious scientific forum, and ask:  "How can I translate this  - it's written in foreign".

I mean, seriously,  if this is the standard of modern contributors to the forum, what hope is there.

  It reminds me of the objection some History students made about an A-level exam paper. The paper included the word "despot".  The students complained that the paper was unfair, as they didn't know what "despot" meant. 

Hi nae, if you're interested in computers you should follow your instinct and go for it.

On 9/12/2020 at 3:34 AM, drumbo said:

No we cannot. As long as you are vulnerable to violence or ostracization you do not have freedom of speech, and you are always vulnerable. Apparently even the most powerful man in the world is vulnerable, hence why the Secret Service exists and believe it or not the POTUS can't say absolutely anything he wants without repercussion.

That's right.  In theory, you can express your opinion . But if your opinion is  "politically incorrect", you will be at the least, ignored, or at the worst, banned from this scientific forum.

On 9/12/2020 at 8:41 PM, Phi for All said:

 

14 hours ago, zapatos said:

That's going to be one big-ass lab.

Yes, it might seem so.  But has it got to be so big-ass - bearing in mind, that the lab only has to provide essential nutrients to sustain our human bodies.

This issue has been addressed in Science Fiction stories loads of times.  Among the most memorable stories are these two:

1. Mordecai Roshwald's sombre  "Level-7". Here the staff of an 4,000 ft- underground retaliatory nuclear bunker receive their first dinner.  It is, they're told -  "scientifically prepared to meet the needs of men and women in this new environment."  The dinner consists of " A small piece of reddish stuff and three pills washed down with half a pint of yellow liquid".  One of the staff, officer X-127, comments on the dinner: "Rather disappointing - it had hardly any taste, but somehow it managed to satisfy our hunger."

2. Harry Harrison's hilarious  "Bill The Galactic Hero". Here Bill, a new recruit in a future Galactic Army, queues up at the cook-house to receive his first army dinner.  He puts his cup under a metal slot, and a thin stream of yellow fluid gushes out, filling his cup half-way.  Bill peers into the cup, and asks the cook: "What is this?"

"What is this!"  the cook shouts at Bill,  "This is your dinner you stupid bowb!  This is absolutely chemically pure water in which are dissolved 18 amino acids, 16 vitamins, 11 mineral salts, a fatty acid ester and glucose. What else did you expect?"

 - "Could I have it without the fatty acid ester? " Bill asks hopefully -   before the enraged cook hits Bill with a soup-ladle.

These fictional tales are interesting and entertaining. But don't they raise a real question:  Do we really need to eat large amounts of animal and vegetative matter, to be digested by our stomachs and turned into nutrients. 

Why can't we ingest the nutrients directly, in the form of tablets and pills?

On 9/17/2020 at 1:14 PM, dimreepr said:

Indeed that's working with nature, but somewhat susceptible to a blight of some sort...

Couldn't we avoid such random blights, by growing our food scientifically,  in  labs. Thus producing safe, nutritious  and clean food, without all the muck.  What's wrong with that?

What is "sleep"? 

2 hours ago, dimreepr said:

Depends on the size of the buffer, we've got to eat.

Could you expand a little on that, please?  How do forest fires affect our ability to eat.   Our digestive systems are entirely unable to process wood, as a source of nutrition.  Therefore, even if forest-fires burned down all the wood, why would that stop us eating?

On 9/7/2020 at 3:30 PM, Area54 said:

Context.

You're correct that "context" can resolve ambiguity.  This is exhibited strikingly in modern English phrasal verbs  - such as "go off".

Suppose one asks the question - what does "go off" mean?  There are many possible answers:

1. "Leave", as in: "I'll go off on holiday";

2. "Explode",  as in: "The bomb will go off";

3. "Start working"; as in: "Your alarm-clock will go off in the morning";

4. "Stop working"; as in: "Your computer will go off if you unplug it";

5. "Become putrid"; as in: "Your milk will go off if you leave it for a month outside the refrigerator";

6. "Stop liking something"; as in: "People like this forum, but if they keep getting hostile responses, they might go off it."

Multiple meanings, distinguished only by context.  In everyday life, the contextual distinctions are obvious.  But is that necessarily so in Science? 

I mean, suppose an Ancient Greek scientist is trying to write a description of his newly-invented steam-turbine, in Greek. And that language doesn't distinguish between "pneuma = steam" and "pneuma = wind".  How will his readers comprehend the significance of the invention?  They might think he's only talking about a wind-mill. 

He could say something like:  "hot pneuma arising from boiling water".  But doesn't such a periphrase confuse thought.  Or,  is it actually more analytical? I dunno.

I think it's still safe to discuss Mathematics and Physics freely,  without worrying about ideological repercussions.

Chemistry is OK too, as long it's strictly the inorganic branch.  But if you venture into Organic Chemistry,  and from that to Biology, the ice begins to get thinner. And If you go further, into Human Biology,  and, even more dangerously, Anthropology, the ice starts audibly creaking.

At that point it's best to stop. For your own safety.  Particularly,  you should in no circumstances whatsoever express publicly any support for the "Multi-Regional"  theory of human evolution.

That theory is now definitely ideologically offensive.  Stick to the alternative  "Out of Africa" theory, which might or might not be scientifically correct, but is politically correct.  By fervently espousing it,  you will send out a strong virtue signal.   Which may protect you from getting arrested in a few years' time, after the Revolution.

8 hours ago, MigL said:

Light is affected by space-time curvature, and, as we use light to determine 'straightness', we can't tell that it bends.

This is an interesting point. Surely we can see that light is capable of bending,  by refracting a ray of light through a prism, or a lens. The same effect is visible when the Sun is setting. As the Sun gets close to the horizon,  it appears bent sideways into a squashed oval shape.  Also changing colour from white to orange or red.

These effects aren't due to any "spacetime" curvature.   Only to refraction of light through a denser medium than a vacuum. In the case of the prism/lens, the medium is glass. And In the case of the sunset, the medium is the Earth's atmosphere.

And isn't the entire Universe filled with a kind of "atmosphere"?  In the form of interplanetary, interstellar, and intergalactic gas.  Admittedly this gas may be very thin.  But it extends for billions of light-years across the Universe.  So it might produce refractive effects on light-beams travelling through it. Could that explain why the light from distant objects appears "red-shifted".  Not because of any accelerating  "expansion of space", or "space-time curvature".

But just an optical effect resulting from  the light's passage through gas?

On 9/3/2020 at 3:42 PM, Markus Hanke said:

Physics doesn’t seek to ‘understand the true nature’ of things (that would be more of a philosophical or at best metaphysical endeavour) - it only seeks to make descriptive models of natural phenomena, formulated in the language of mathematics. 

So -  it's back to "saving the phenomena" is it?   That was the notorious term used in Astronomy,  until the 16th and early 17th centuries.

Back then, astronomers were working on an entirely erroneous theory, descended from Aristotle.  It was that the Earth is the centre of the Universe.  With all other celestial objects, planets and stars, revolving round the Earth in perfect circles.   This is not true, physically.   But the astronomers argued this way:

Astronomy is not about physical reality.  It's only concerned with successfully predicting astronomical phenomena - such as eclipses and conjunctions.  And our geocentric theory can do this.  If we make enough tweaks to it  -  by adding imaginary devices such epicycles, deferents, and the punctum aequans.   These may not represent physical reality.  But they enable us to mathematically  "save the phenomena"!

It seems to me that modern Physics is retrogressing into a similar attitude.

2 minutes ago, Markus Hanke said:

There is nothing here that needs to be refuted - spacetime is a mathematical model, a description of certain aspects of reality, in the same way that a map is a description of some territory. Would you argue that maps don't mean anything, just because they are not identical to the territory? Of course not. Instead, you ask to what degree of accuracy they reflect the real territory, in the sense that whether or not the map can get you from A to B without you getting lost. If it can, then it is a good map, if not then it needs to be discarded or revised.

The concept of spacetime is no different - does it accurately model the dynamics of test particles under the influence of gravity (or in relative motion, or both)? Within its domain of applicability, it evidently does a pretty good job at that.

There are other examples of this in physics, like electromagnetism, or thermodynamics. 

This is not how it is understood at all. It's a mathematical model, not a 'real thing', whatever that even means.

Thanks Markus for your reply.  The thrust of your argument does however  disturb me a bit,  I take your point about maps, and their usefulness. But  maps are after all, small-scale representations of reality.  In the sense that everything on the maps, does represent something that physically exists.  For example, if the map shows a church at a particular location, that church really exists.  It may be drawn on the map in a symbolic form,  but if you go there, you can see the actual physical object, with its stonework, steeple and so on.  It's not a "mathematical model". It really exists. 

That's why I find it difficult to follow your argument about "spacetime".  You seem to be proposing  that "spacetime" doesn't necessarily exist - it's  only a convenient model for doing the calculations and arriving at the correct answer.

Much the same, I suppose, that when navigating a ship across the ocean, it's convenient to model that the ocean is divided into lines of Latitude and Longitude.  Even when those lines don't physically exist, stretching across the surface of the sea.

I get that.   But I still find it upsetting.  You seem, with respect, to be retreating from  the scientific quest  to discover the true nature of the Universe, to a utilitarian  approach:

In the infamous words of the physicists:

"SHUT UP AND CALCULATE". 

No offence meant, and thanks again for communicating with me - I appreciate it.

40 minutes ago, MigL said:

Your eye bends light by refraction, the 'slowing' of light, as it passes from a less dense material to a more dense material, due to increased absorption/emission events.

Planets, stars and galaxies bend light gravitationally, and the Sun will bend light passing tangentially ( close ) to its surface, by only about 1.75 arcseconds.
 

Thanks Mig for pointing out the distinction between refractive effects  and gravitational field effects - I'm very much obliged.to you!

On 6/24/2020 at 6:13 AM, Markus Hanke said:

You cannot separate time and space, they always exist together as spacetime, regardless of whether the region in question is a vacuum or not.

The word "spacetime" is interesting.  It contains two separate nouns: "space" and "time",  joined  together to create a  new noun:  "spacetime"

And as a noun generally corresponds  to a  real "thing",  we are  led to think that "spacetime" must also be a real "thing".

But ,you could take any two separate nouns, say "cheese" and "clock" . Then join them together to create a new word :"cheeseclock".

Then insist that  "cheeseclock" must  be a real thing because there's a word for it.  But no - It's just a made-up word.  It doesn't mean anything 

And I suggest that so-called "spacetime" is also a made-up word that doesn't mean anything.  

"Space" and "Time" are two different things.  Pushing them together into one word doesn't make them the same.   It's just a linguistic illusion.

Or am i wrong.?  I'd welcome a well-reasoned refutation!

1 hour ago, swansont said:

It’s a matter of how much curve, and the thing about physics is we quantify things. So the question becomes “how much curvature?” The amount of lensing from the sun was hard to measure. The lensing from the earth would not be visible to the naked eye.

When you mention the "naked eye",  doesn't it seem curious that the tiny drop of "protoplasm" (I use the deplorably unscientific term loosely) in the lens of your eye, or the even smaller glass lens in your smartphone, can bend light sufficiently to produce sharp, detailed, distinct images.  Whereas the gigantically, vastly greater mass of planets, stars, and galaxies, with a "focal length" extending across the Universe for millions of light-years, can't bend light-rays enough to provide anything but a vague blurry image.

It seems a poor show to me.  Can't the Universe do better?  Could we improve its performance by designing "corrective" lenses to increase resolution?

1 minute ago, Sensei said:

A single word can have multiple definitions.

What's wrong with the definitions on this page?

https://en.wiktionary.org/wiki/λόγος

The definitions are not fixed. They evolve over time.

Thanks Sensei.  But the definitions on your page are too many for precision?  How can a word how so many different meanings, and still be clear?

I've often thought that was why the Ancient Greeks never made much progress in Science.  

Science requires precision, and the ability to distinguish fine shades of meaning - such as between work, force, and. energy.  The Ancient Greek language  did not make these distinctions. It had no word for our modern concept of "energy".  Their Greek word "energia" meant literally "in work".  Which misses the point.. There was a similar lack of precision in most Greek abstract nouns.  

For example, they had no word for "science" - there was only the word ""techne" which connotes "making,  art, craft"  and so on.  This blurriness extends to words like "pneuma", which seems to connote mist, vapour, soul, spirit, wind and steam. So it's little wonder the Greeks experimented with a primitive steam-turbine, but never carried it much further,, when they didn't have a proper word for "steam".

May I add that this lack of precision in the Ancient Greek language is shown in fields other than purely scientific.  Many translators of Thucydides have complained about the difficulty of understanding what he was trying to say.  It all comes down to lack of enough words.  When I look at my "Oxford Classical Greek Dictionary", the lexical impoverishment is stark. Every Greek word has dozens of different meanings. Some completely contradictory.  All the nuances of meaning, such as we have in modern English, are lost.

And that, I think, explains why the Greeks got nowhere in Science.  Their language didn't permit it.

If I may,  I'd like to ask a question. 

In  the "Ancient" or " Classical"  Greek language,  there's a frequently used word:

"LOGOS"

My question is  -  what exactly does it  mean?

If anyone here can give a precise, unambiguous,  definition of this word,  I will personally post a nude photo of myself on the forums.

And to those who rightly shy away from such a hideous prospect,  may I offer this reassurance::

The word "LOGOS"  is so vague, indeterminate, and ambiguous, that it utterly fails the test of translation into precise, lucid English. 

Therefore I'm confident that no personal exposure will be required.

Can you prove me wrong?

Thanks Endy.  Do you think the photograph of the supposed "Black Hole" id very convincing.  It  looks like a blurred  image of a distant  planetary nebula.

As for "Dark Matter",  is there really such a thing.  There's no evidence for it.

Except  to account for apparent anomalies in galactic rotation.

But might these anomalies be explained, more normally, by  the presence of meteorites within, and outside the galaxies.