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Re: How does gravity work?

Posted: Fri Feb 24, 2017 9:24 pm
by uwot
wtf wrote:But "big bang stuff?" What is that?
Well, if the universe is made of anything, then it behaves exactly as physicists observe it doing. And if the Big Bang describes an actual event, then big bang stuff is the stuff it happened to. It's basically what you get if you mix Guth's eternal inflation and Higgs' field.

Re: How does gravity work?

Posted: Fri Feb 24, 2017 9:30 pm
by uwot
attofishpi wrote:Are you familiar with Sean Carrol? I've seen other docos where he's been involved and am impressed with his ability to explain these complexities at the sub-atomic world.
I am, and I agree, he is really worth watching.

Re: How does gravity work?

Posted: Fri Feb 24, 2017 9:31 pm
by uwot
Cerveny wrote:Well, boys, enjoy (and measure) your Emperor's New (even expanding) Clothes ("empty space")
Thanks Cerveny, as long as there's beer here, I will.

Re: How does gravity work?

Posted: Fri Feb 24, 2017 10:03 pm
by wtf
uwot wrote:
wtf wrote:But "big bang stuff?" What is that?
Well, if the universe is made of anything, then it behaves exactly as physicists observe it doing. And if the Big Bang describes an actual event, then big bang stuff is the stuff it happened to. It's basically what you get if you mix Guth's eternal inflation and Higgs' field.
But this is both incoherent and vacuous. Gravity is what the big bang did and that's why there's gravity. What you just wrote is very unsatisfactory.

Big bang stuff is the stuff it [the big bang] happened to? So first there was stuff, then the big bang happened to it? That's the story you're going with?

Re: How does gravity work?

Posted: Fri Feb 24, 2017 10:15 pm
by uwot
wtf wrote:
uwot wrote:
wtf wrote:But "big bang stuff?" What is that?
Well, if the universe is made of anything, then it behaves exactly as physicists observe it doing. And if the Big Bang describes an actual event, then big bang stuff is the stuff it happened to. It's basically what you get if you mix Guth's eternal inflation and Higgs' field.
But this is both incoherent and vacuous. Gravity is what the big bang did and that's why there's gravity. What you just wrote is very unsatisfactory.
Could you quote me? If that is what I said, you have done me a favour, because that bit would need changing.
wtf wrote:Big bang stuff is the stuff it [the big bang] happened to? So first there was stuff, then the big bang happened to it? That's the story you're going with?
Yup. I have no idea where big bang stuff came from, but all the evidence suggests that something went bang.

Re: How does gravity work?

Posted: Fri Feb 24, 2017 10:19 pm
by SpheresOfBalance
wtf wrote:
uwot wrote:In a word: refraction. Details in the usual place: http://willijbouwman.blogspot.co.uk
Is this a joke? Your explanation of airplane lift is wrong and ignores wing dynamics. Your explanation of gravity is laughable.
He wasn't talking about lift, he was talking about gravity. To me it just seems like a funny way to do so, even while understanding that he's trying to explain the concept in as basic a way as possible. It felt like it had the opposite effect of what he was trying to achieve. But then your mileage may vary.

For those interested: Lift is created because of the air foil design, which is used in both fixed and rotating wing aircraft. On top, the air foil is curved and on the bottom it's flat. Because the air flowing across the bottom of the airfoils surface has less distance to go, it causes a higher air pressure on the bottom. The air flowing across the top has a longer way to go, which creates a lower air pressure on top. The higher air pressure on the bottom causes the aircraft to rise. The elevator, which is attached to the trailing edge of the horizontal stabilizer, at the rear of a fixed wing aircraft, can be manipulated either up or down which either opposes or complements the natural tendency of the wing to rise, thus allowing the pilot to control whether the craft ascends or descends. On a rotating winged aircraft the wings are variable pitched so as to either ascend or descend. Of course as to uwot's explanation of gravity, all this says is that gravity can be successfully opposed with the manipulation of air pressure, because we have an atmosphere. In space, without an atmosphere, only thrust in the opposite direction of desired movement can be used as a means to control a space craft. Which is why I sometimes hate Hollywood! ;-)

But then surely I digress, so now back to your regularly scheduled program, which thankfully, has absolutely nothing to do with Hollywood...

Re: How does gravity work?

Posted: Fri Feb 24, 2017 10:37 pm
by wtf
uwot wrote: Could you quote me? If that is what I said, you have done me a favour, because that bit would need changing.
uwot wrote:big bang stuff is the stuff it happened to.
Someone using your handle wrote those words. You have a cat maybe? Walking on your keyboard?

Re: How does gravity work?

Posted: Fri Feb 24, 2017 10:52 pm
by uwot
wtf wrote:
uwot wrote: Could you quote me? If that is what I said, you have done me a favour, because that bit would need changing.
uwot wrote:big bang stuff is the stuff it happened to.
Someone using your handle wrote those words. You have a cat maybe? Walking on your keyboard?
Fair enough, that is clumsily put. Like I said, I have no idea where big bang stuff came from, but the point I am making is that if the universe originated in a single point, and if the universe is actually made of something, then it is made of the same stuff as the original single point.

Re: How does gravity work?

Posted: Fri Feb 24, 2017 10:56 pm
by uwot
SpheresOfBalance wrote:Lift is created because of the air foil design...
Absolutely true, but will an aeroplane take off if it doesn't divert a whole load of air downwards by lifting it's nose?

Re: How does gravity work?

Posted: Fri Feb 24, 2017 11:16 pm
by wtf
uwot wrote:
wtf wrote:
uwot wrote: Could you quote me? If that is what I said, you have done me a favour, because that bit would need changing.
uwot wrote:big bang stuff is the stuff it happened to.
Someone using your handle wrote those words. You have a cat maybe? Walking on your keyboard?
Fair enough, that is clumsily put. Like I said, I have no idea where big bang stuff came from, but the point I am making is that if the universe originated in a single point, and if the universe is actually made of something, then it is made of the same stuff as the original single point.
Wow. All the stuff was in the point, and now the stuff is all over the place and that's gravity? I'm trying to give you the benefit of the doubt but I'm not able to discern the slightest common sense or knowledge of physics in what you write. So ok, I'll take you at your word. The stuff of the big bang is now all over the universe. What does that have to do with gravity? You've explained nothing.

Re: How does gravity work?

Posted: Fri Feb 24, 2017 11:33 pm
by uwot
wtf wrote:Wow. All the stuff was in the point, and now the stuff is all over the place...
That's the basic Friedmann–Lemaître–Robertson–Walker model.
wtf wrote:...and that's gravity?
The idea that there is a mechanical field is yer basic Higgs.
wtf wrote:What does that have to do with gravity? You've explained nothing.
It's all in the blog.

Re: How does gravity work?

Posted: Sat Feb 25, 2017 12:05 am
by Cerveny
uwot wrote:
wtf wrote:But "big bang stuff?" What is that?
Well, if the universe is made of anything, then it behaves exactly as physicists observe it doing...
There would be found a few unimportant trinkets: "dark matter" (70% of the Universe) and seventy years of hopeless quantization of GTR...

Re: How does gravity work?

Posted: Sat Feb 25, 2017 12:32 am
by Cerveny
uwot wrote:
Cerveny wrote:Well, boys, enjoy (and measure) your Emperor's New (even expanding) Clothes ("empty space")
Thanks Cerveny, as long as there's beer here, I will.
Cheers!
https://1drv.ms/i/s!Av5Q8bX1QJm1jSb0lZrVXuiMQMHT

Re: How does gravity work?

Posted: Sat Feb 25, 2017 12:49 am
by uwot
Cerveny wrote:
uwot wrote:
wtf wrote:But "big bang stuff?" What is that?
Well, if the universe is made of anything, then it behaves exactly as physicists observe it doing...
There would be found a few unimportant trinkets: "dark matter" (70% of the Universe) and eighty years of hopeless quantization of GTR...
You are getting dark matter mixed up with dark energy. Dark matter is reckoned to be something shy of 30%, while it is dark energy that is almost 70%; it is the left overs from that which is the visible universe.
Both are posited to account for the observable behaviour of the visible universe. In the case of dark matter, the issue is that galaxies do not contain enough visible matter to generate the gravity that would prevent them flying apart at the rate they are spinning. Dark energy is the hypothetical explanation for the fact that the expansion of the universe appears to be accelerating. The clue is in the name, the cause of these phenomena is not clearly understood, hence 'dark'. As it happens, they are likely to be the subject of my next post.
That GR and QM aren't easily compatible has no bearing on the fact that both describe what they describe extremely accurately.
Anyway, do you have an explanation for the phenomena?

Re: How does gravity work?

Posted: Sat Feb 25, 2017 12:53 am
by uwot
Cerveny wrote:Cheers!
And to you, sir. Urquell is a very fine pint.