gravity 101

[Eratosthenes (Peter)]

Originally Posted by xelasnave

Peter could you expand upon and explain your last sentence.

http://www.sns.ias.edu/~malda/sciam-maldacena-3a.pdf

https://m.youtube.com/watch?v=NblR01hHK6U

There are some interesting articles on the illusion of gravity - in fact Einstein referred to the illusion of gravity many times

[xelasnave]

Thank you Peter.
Newton said gravity was the force of God or words implying similar.
GR needs no force.
Equivalences suggests fictitious force.
Is there a reason the concept of force seems to be avoided.

[sjastro]

Originally Posted by Eratosthenes

http://www.sns.ias.edu/~malda/sciam-maldacena-3a.pdf

https://m.youtube.com/watch?v=NblR01hHK6U

There are some interesting articles on the illusion of gravity - in fact Einstein referred to the illusion of gravity many times

Einstein referred to gravity as a fictitious force. Fictitious forces are not illusionary because they can be measured.
An accelerometer located inside a car will measure the backwards proper acceleration due to the fictitious force as the car is subjected to a forward coordinate acceleration.
When you stand on your bathroom scales the proper acceleration is directed upwards and opposite to the coordinate acceleration due to gravity.
Otherwise you would fall straight through the scales.

[Eratosthenes (Peter)]

Originally Posted by xelasnave

Thank you Peter.
Newton said gravity was the force of God or words implying similar.
GR needs no force.
Equivalences suggests fictitious force.
Is there a reason the concept of force seems to be avoided.

.... on that reasoning, all forces may well be fictitious in essence, or perhaps merely different manifestations of the same entity/phenomena??

sadly scientific disciplines such as physics have been corporatised on an almost global scale with only small pockets of cutting edge research. In the USA for example the elite Physics and mathematics PhDs end up being snapped up by the Pentagon (working on WMDs, defense systems etc) and the Stock market (working on market predictions and other complex systems). They sometimes receive an order of magnitude additional pay to carry out these ridiculous projects motivated by paranoia, fascist ideologies and material greed.

Mediocre physicists such as Lawrence Krause, Green and De Grasse are left to gallop around the planet promoting Atheism and pedaling trivial sensationalist Physics - the cartoon characters of Academic Hollywood.

Science has essentially become a corporate cult religion - and driving itself backwards in a real hurry - if it wasnt globally pathetic it would be a gut splitting stage comedy.

[xelasnave]

Steven I read the links you posted and I found them very helpful. Thank you.
Peter I am just a layman and so cannot comment on your view of the world of science other than to say it is an ill wind that does not blow some good.
I see it this way..it is good that there is paid work for folk who have taken time to gain respectable qualifications, even if it is the Pentagon.
The military gives us many inventions that finally benefit the public.
I think glad wrap was originally a worked up version of protective covering for jets on aircraft carriers.
As for preaching atheism I applaude such.
I believe religion has past it's use by date.
Any attempt to bring humans out of the dark ages must be good.

I still don't understand the choice of words "fictitious force.
In law there was a time where "fictions" were used...perhaps my response is due to having to study why their use was necessary.

[Eratosthenes (Peter)]

Originally Posted by xelasnave

Steven I read the links you posted and I found them very helpful. Thank you.
Peter I am just a layman and so cannot comment on your view of the world of science other than to say it is an ill wind that does not blow some good.
I see it this way..it is good that there is paid work for folk who have taken time to gain respectable qualifications, even if it is the Pentagon.
The military gives us many inventions that finally benefit the public.
I think glad wrap was originally a worked up version of protective covering for jets on aircraft carriers.
As for preaching atheism I applaude such.
I believe religion has past it's use by date.
Any attempt to bring humans out of the dark ages must be good.

I still don't understand the choice of words "fictitious force.
In law there was a time where "fictions" were used...perhaps my response is due to having to study why their use was necessary.

Atheism is just another fundamentalist religion sprinkled with its fair share of dogmatism and fanaticism.

A little bit like Science actually

[RB (Andrew)]

Topic is Gravity guys.

[xelasnave]

Side issues really and irrelevant to gravity.
I once believed there could be no force of attraction...how say you.

[xelasnave]

In reflection I withdraw my question.

[Eratosthenes (Peter)]

Originally Posted by xelasnave

Side issues really and irrelevant to gravity.
I once believed there could be no force of attraction...how say you.

....the force of attraction between two oppositely charged particles is only partially true and dependent on the separation distance. Opposite charges will attract one another, but when the distance becomes very small, there is a repulsive force.

It's often said that in personal relationships, opposites attract. Well it could mean that this is true only up to a point - close relationships between opposite characters are repelled - opposites keeping their distance. What is that repulsive force again?

http://www.antonine-education.co.uk/...orce_graph.JPG

[CarlJoseph (Carl)]

Originally Posted by Eratosthenes

What is that repulsive force again?

Forces at this scale are called van der Waal forces. The repulsive force is due to the Pauli exclusion principle and electron degeneracy pressure. Perhaps that's what you're thinking of?

[sjastro]

Originally Posted by Eratosthenes

....the force of attraction between two oppositely charged particles is only partially true and dependent on the separation distance. Opposite charges will attract one another, but when the distance becomes very small, there is a repulsive force.

It's often said that in personal relationships, opposites attract. Well it could mean that this is true only up to a point - close relationships between opposite characters are repelled - opposites keeping their distance. What is that repulsive force again?

http://www.antonine-education.co.uk/...orce_graph.JPG

What has this got to with gravity?

Your link refers refers to the electrostatic (Coulomb force) between a positively and negatively charged atom which form an ionic bond.
Bring the atoms in closer and the electrons from each atom repel each other. The zero point for force occurs when the repulsive force equals the attractive force. The magnitude of the attractive force is at a maximum when the repulsion force is at a minimum. Separate the atoms further and the Coulomb force decreases as the inverse square law for distance.

[Eratosthenes (Peter)]

Originally Posted by Afro Boy

Forces at this scale are called van der Waal forces. The repulsive force is due to the Pauli exclusion principle and electron degeneracy pressure. Perhaps that's what you're thinking of?

indeed Afro Boy.....

time for some Calypsonians from the Taj

https://www.youtube.com/watch?v=UFh46LvV1DQ

[sjastro]

Originally Posted by Eratosthenes

indeed Afro Boy.....

time for some Calypsonians from the Taj

https://www.youtube.com/watch?v=UFh46LvV1DQ

Yeah sure you were thinking of electron degeneracy pressure and van der Waal forces.
Strange how your link tells a totally different picture.
http://www.antonine-education.co.uk/...orce_graph.JPG

Since you find Physics relativity simple you should be able to answer the following questions.

(1) Why does the zero force point of the graph occur at an atomic radius scale and not at a molecular scale as one would expect for van der Vaal forces?
(2) Why does the force reach an asymptotic value as the distance approaches zero given that electron degeneracy pressure essentially makes an atom "incompressible" and therefore impossible to approach "small" distances?

[bojan]

Check this:
emergent gravity or superposition of states?
Looks like cat can't be dead AND alive after all

http://www.scientificamerican.com/ar...SA_WR_20150624

http://physicsworld.com/cws/article/...-superposition

[AlexN]

I know I've experienced superposition a few times in a very classical way.

I believe that a usb plugs initial state is a superposition. Every time I plug a usb lead into a computer (without looking first. Observation causes decoherance) it is upside down, so I flip it over, try again.. Still won't plug in. So I take a look, flip it back to the original orientation and wouldn't you know it, Goes in fine when earlier in the same orientation it wouldn't.

This tells me that prior to observation the usb plug is both right side up and upside down at the same time. Only after direct observation does the quantum superposition become decoherant and it falls back to a classical state.

That's quantum mechanics interacting with every day life on a large scale object despite the presence of gravity.

#nomathematicsrequired

[rustigsmed (Russell)]

Originally Posted by AlexN

I know I've experienced superposition a few times in a very classical way.

I believe that a usb plugs initial state is a superposition. Every time I plug a usb lead into a computer (without looking first. Observation causes decoherance) it is upside down, so I flip it over, try again.. Still won't plug in. So I take a look, flip it back to the original orientation and wouldn't you know it, Goes in fine when earlier in the same orientation it wouldn't.

This tells me that prior to observation the usb plug is both right side up and upside down at the same time. Only after direct observation does the quantum superposition become decoherant and it falls back to a classical state.

That's quantum mechanics interacting with every day life on a large scale object despite the presence of gravity.

#nomathematicsrequired