Charles 3781

1 hour ago, joigus said:

Magnets do have energy density proportional to the field squared. Maybe the bell that's ringing in your head is that a magnetic field doesn't do work on a moving charged particle.

If that's the case, it's true that a magnetic field doesn't do work on a charged particle with velocity v, because the force is perpendicular to the displacement.

Magnets acting on each other also have energy.

Thanks joigus,  I know magnets have energy, as you say, because if you take two magnets, and try to push them together against their opposite poles, they won't come together no matter how hard you try to force them.  The question is this:

How can two lumps of inert metal create such resistive force out of nothing?

2 minutes ago, zapatos said:

MigL also said "Once they 'eat' all close by mass via their accretion disc, they can't overcome farther out stable orbiting material, and stop growing."

His point being that anything close enough to be readily consumed by the BH has already been consumed. Nothing else is close enough to be impacted by  the extreme gravity found in the near vicinity of a BH.

Yeah, but surely "Gravity" doesn't depend on "Mass" but also "Distance" - Inversely Squared.  Therefore if a Black Hole  gets smaller in size as it contracts, its gravitational pull diminishes.

30 minutes ago, MigL said:

As Joigus says, the gravity produced by a BH is no different than from any other equivalent mass.
If expansion can overcome the gravity of galaxy clusters, it can similarly overcome the gravity of a BH composed of the masses of the equivalent number of stars in that galaxy cluster.

There is no upper limit on BH size.
There is only a limit to how much you can feed them.
Once they 'eat' all close by mass via their accretion disc, they can't overcome farther out stable orbiting material, and stop growing.
Direct collapse, however,without going through star lifetimes, is a totally different mechanism.

I'd like, if I may, to pick up on one issue..  MigL citing a previous post from Joigus,  makes this statement:

"The gravity produced by a BH is no different from any other equivalent mass". 

Now, I wonder whether this takes into account,  the Black Hole's extremely small  physical dimensions. 

 Wouldn't these small dimensions cause a drastic reduction in the BH's ability to exert gravity.  Following the diminishing inverse-square law from its outer surface?

Isn't the point of calculus this  -  only proper mathematicians can understand it.

29 minutes ago, iNow said:

Bullshit

So how do magnets retain their pulling force, without any input of kinetic energy?  I mean suppose you said: 

 "I've invented a new fuel-less car.  It's got magnets  which will pull it towards your destination.  Then when  you want to go home,  you turn the car round, and the reversed polarity of the magnets will repel it back to your starting point."

Without the car using any petrol during your travels.  Is that credible?

Just now, Kartazion said:

According to many people, the whole universe was born from nothing.

Don't you mean, "according to scientists", the whole Universe was born from nothing?    

Suppose you were asked, "Where did your  computer come from?"  And you said:  "That's a meaningless question - it came from nothing."   How would you respond?

12 minutes ago, Phi for All said:

The reputation system is a weird blend as a gauge of how much a poster contributes. Every member gets one vote on each post, even staff. You talk down about science quite a bit, so perhaps you've acquired some haters (or misread your audience?). You seem to enjoy an aspect of competition that embraces denigration of a perceived "opponent", which is very common in people who like to "debate" what they think they know. All of this tends to sit poorly with people who just want to discuss science and learn.

We have to hope you don't start really trying.

It's all about expanding my own ego. The more I know, the more everybody has to listen to me and do what I say and be just like me. Eventually, I'll just kick you all out and write all this stuff myself. My brain is all that's needed to explain everything to everybody. 

Or... or, discussion with peers is part of a successful methodology, and it needs a place where that's respected with as much rigor as we can apply with volunteers.

That is the most honest, insightful and truthful post that I 've seen on here.  Well done!

According to current theory, didn't the entire Universe spring from a minute "Black Hole" smaller than a proton. Then expanded outwards. To create trillions of stars, galaxies and so on.

Given the wide vista of prospects allowed by such a theory,  would you rule anything at all out,  as physically impossible?

11 minutes ago, Victheromanian said:

i put energy to get them far apart but the magnets pull them-self together by they own. i think it almost equals out. but that is what you think?  the pulling away of the magnets or them pulling each other together converts into electromagnetic energy ? 

Yes it might be.  To pull the magnets apart, you have to use physical force, and this force is equalised when the magnets come together again, so the overall expenditure of force is balanced.

7 minutes ago, zapatos said:

First, the mods did not create this site; they are volunteers.

Second, stop being so insulting to everyone.

Third, if you don't care to contribute to meaningful discussions you know where the door is.

I try to contribute, but every time  I do,  my posts  get red negative marks stuck on them, which is very hurtful

2 minutes ago, Phi for All said:

You spread ignorance with such conviction. That's a dangerous trait, and one that seems to be gaining strength in our society despite access to so much information. See Dunning & Krueger.

The original owner of the site (aka Administrator) was in med school when he asked me to moderate. He's a doctor now, expanding his own ego in the pursuit of medicine, saving lives, but he still checks in every now and then. The current Admins/owners are brilliant as well, expanding their egos in the fields of computers and chemistry. It's easy to see how big their egos are by all the advertising dollars they reap from this site, and the way they stop people like you from saying bad things about their science discussion forum. 

 

Thanks Phi, for the information.  I'm not really trying to say "bad things" about the forum.  I just wonder why you go to the trouble of keeping it going.

10 minutes ago, Victheromanian said:

i have a vise and i stick both of my big 2700 Gauss each on either side and then put a small 500 Gauss in the middle and close the vise . did this for 200 times and the magnetic reading didn't change. how can that be i asked k&j and they said that this is normal how can that not brake the 1 law?

Vic,  when you changed the spatial position between the magnets and your visa, you  had to expend kinetic energy -  by employing physical movement -  and this movement was converted into electromagnetic energy, which restored the steady state of the magnetism.

On 10/9/2020 at 1:16 AM, MSC said:

I disputed the truth/validity of a moderators pride? Uhm... Okay.

The mods here don't strike me as the sort to care if I disagree with them or not and I doubt they have plans for retribution. All I know is, I'm glad you're not a moderator. 

Look MSC, the Mods created this site.  Why do you think they did that?  Was it to further the progress of Science.  Or was it  or another reason.  Such as expanding their own ego's?

1 hour ago, swansont said:

How are you magnetizing the other magnets? Somewhere, work will be involved, or some other energy transfer.

The magnetic field does contain energy, and would diminish if no energy is added to the system.

When you  say  "How are you magnetising the other magnets",  I think you have in mind rubbing a magnet against a bit of non-magnetised iron..  Thereby turning the second bit of iron into a magnet.  This can be plausibly explained, by a transfer of kinetic energy from the "rubbing" between the two bits of iron.

On 10/9/2020 at 5:29 PM, swansont said:

We are almost certainly limited this way, but that’s why we build instruments. They can be sensitive to signals that humans aren’t 

That's a profound truth.  If we were dependent solely on our limited human senses,  we wouldn't know much about the Universe.

It's only by building instruments, such as telescopes, microscopes, and spectroscopes,  that we have increased our knowledge.

2 minutes ago, swansont said:

Yeah, that’s relevant...

Gas and snakes are hypothetical? WTAF are you talking about?

OK, Ok, I retract the gas bit.  Tear-gas has been fired at protesting crowds by your US enforcement agencies.  But  to my knowledge, the US has not yet made use of a snake, unless you count your President.

Just now, swansont said:

Fair enough, but that’s the context of the comments about shouting fire, gas or snakes.

 

You Americans are more used to firing guns and shooting each other, so I defer on that point,  As regards gas and snakes, neither of our two peoples has yet employed such methods, so it remains a hypothetical, and probably quite impracticable scenario for future civil unrest in our respective countries.

2 minutes ago, joigus said:

What if language/ideas is a self-organizing superstructure that's using us to build something we cannot intuit yet? I think that's very much what's happening, actually.

Your expression "a self-organising superstructure"  does have an appeal.  When we study languages, we notice that they always have a "structure".

The words contained in a language, are not mere random collections of syllables.  They're organised into patterns governed by "rules".  For example, in the Latin language,  all nouns fall into five different patterns, or "declensions".  And within each declension,  every noun has a terminal "inflection",  or "case ending", according to the grammatical function that the noun performs.

The functions, in Latin, are "Nominative", "Vocative" "Accusative", "Genitive", "Dative", and "Ablative".  There are similar complexities in the Latin verbs.  Four different patterns, or "Conjugations" of verbs.  Each with a terminal ending, according to whether the verb functions as Singular, Plural, Present Tense, Imperfect Tense, Perfective Tense, Pluperfect Tense, or Future Tense. Also whether the verb functions in "Indicative", "Subjunctive" or "Imperative" Mood.  Or as participle, gerund, or gerundive.

Such a maze of complexity!  Surely no human  brain would have thought it up!  It must come from some higher superstructure, or "organising principle", that's perhaps inherent in the Universe. 

36 minutes ago, swansont said:

Have you any better examples of speech not protected by the first amendment?

I'm not sure about the First Amendment, and what protection it confers under your written Constitution.  That's a matter for you Americans.

We British have been wise enough not to even attempt drawing up a written constitution. Such a thing can only create a field of mayhem for lawyers to dispute over.  As you keep finding out in the US.  With your lately occurring paralyses of Government and embarrassingly abortive impeachment trials of your President.

Here in the UK, we stick to an un-written constitution.  This is vastly preferable. Because when the constitution isn't written down, the lawyers can never find documentary evidence to impeach a Prime Minister for violating it.

Doesn't that make sense?

3 minutes ago, MigL said:

As an example of 'free' speech, you can use any of the above words, "Fire', "Shoot" and "Poison Gas" in a sentence, so as to express an idea.

"I should be able to kill SNAKES by SHOOTing, POISON GAS or FIRE"

See, no problem.

 

That's very pretty, Migl.  Completely irrelevant, and not even all that ingenious, but a worthy reply.

3 minutes ago, swansont said:

!

Moderator Note

You didn’t start this thread. I split it.

 

See MSC,  you impugned a moderator's pride.  Lord knows how he will exact retribution on you!

3 minutes ago, Phi for All said:

No, they're a reply to sophistry.

To show that some things can't be allowed, by constitutional right, to be spoken at any time a person feels like it.

No, it's to show that some things can't be allowed, by constitutional right, to be spoken at any time a person feels like it. What a bizarre strawman, btw. I'm sorry you feel so intellectually cornered that you resort to fallacy. Is it because you don't understand what free speech is in this context?

 

Phi, I'm not  "intellectually cornered" as you put it.  I just wonder why some intellectual persons such as yourself, can't seem to discuss political questions without resorting to terms like  "SHOOT" "FIRE" and  "POISON GAS" . 

The use of such terms conveys a very unfavourable impression.   Don't they make you, and others of your ilk, appear emotive, violent, and potentially extremely dangerous.

At least that's the way it seems to me.  You sound quite scary!

On 10/7/2020 at 2:59 PM, dimreepr said:

Indeed, how dare they tell me who I can shoot...

On 10/7/2020 at 2:30 PM, Phi for All said:

I get nervous when I ride in packed subway trains, and I find that yelling out my biggest fears helps me overcome them. I wish you were in charge, because I keep getting arrested whenever I scream "FIRE" or "POISON GAS" or "SNAKES". I'm only trying to show who I am by expressing myself this way. Why do they keep taking away my freedom of speech?

Aren't these replies just sophistry?  Why do they use emotionally-loaded negative words such as "SHOOT"  "FIRE"  "POISON GAS"  "SNAKES" .

Is it because they're trying to portray anyone who defends free speech as a  horrible person. 

5 minutes ago, joigus said:

In my case, it had nothing to do with god; it was that the process of believing itself ground to a halt.

I no longer believe anything.

I empathise with you.  I don't believe in Black Holes, Gravitational Waves, and especially the Higgs Boson.  These absurd figments of the imagination have undermined our belief in Science.

But they are only passing phenomena.  Comparable to "epicycles" and "phlogiston" in the history of Science.  They will soon be exploded and dismissed,  as Science progresses.

As regards God,  I think He's probably a manifestation of the future collective intelligence of the human species, when we have achieved, through Science, the ability to travel through time.

1 minute ago, iNow said:

This thread isn’t about buoyancy in the ocean. It’s about bone loss in space 

How is it different?  If you're buoyant in the ocean, aren't you, in effect, experiencing no gravitational force.  Just like in free-fall space orbit. Isn't that why astronauts practice space missions in big tanks of water.  Whales and dolphins spend their whole lives in the water without suffering bone-loss.

I know this another thread derailment.  Please delete it, if you think it advisable.

2 hours ago, CharonY said:

Why would you think that there is no gravity in oceans? 

Thanks  CharonY.  Well of course I know gravity permeates the whole Earth, including its oceans. But I thought that in the oceans, the downward pull of gravity gets nearly cancelled out by the upward push of water-pressure.  Thus allowing mammals like whales to thrive in a nearly zero-G environment.   Without ill-effects. That's all I was saying.  Is it wrong?