Are different physical fields located in the same space-time, or in different ones?

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A field assigns a value to every point in, this case, spacetime. If the value is scalar, it's called a scalar field, if it's vector valued it's a vector field, and so on. Newtonian gravity is modelled as a scalar field, EM is modelled as a vector field, Einstein gravity is modelled as a set of tensor fields. They all are found at every point spacetime.
 
QuarkHead said:
A field assigns a value to every point in, this case, spacetime. If the value is scalar, it's called a scalar field, if it's vector valued it's a vector field, and so on. Newtonian gravity is modelled as a scalar field, EM is modelled as a vector field, Einstein gravity is modelled as a set of tensor fields. They all are found at every point spacetime.
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Newtonian gravity is a vector field, surely? Or do you mean gravitational potential, which would be scalar?
 
QuarkHead said:
A field assigns a value to every point in, this case, spacetime. If the value is scalar, it's called a scalar field, if it's vector valued it's a vector field, and so on. Newtonian gravity is modelled as a scalar field, EM is modelled as a vector field, Einstein gravity is modelled as a set of tensor fields. They all are found at every point spacetime.
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Тогда зачем понадобились лишние сущности в виде различных полей, если это по сути своей одно и то же пространство-время?
 
ольга said:
Then why were extra entities in the form of various fields needed if this is essentially the same space-time?
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Look. Right now, at every place on Earth (in fact, every place in space as well) there are many, many properties.
No matter where you are, there is a value for
- the temperature
- the degree of brightness
- the magnetic field strength
- the gravitational potential
etc.

Are any of these "extra entities"?

These are not properties of space time; they are fields in space time.
 
DaveC426913 said:
Look. Right now, at every place on Earth (in fact, every place in space as well) there are many, many properties.
No matter where you are, there is a value for
- the temperature
- the degree of brightness
- the magnetic field strength
- the gravitational potential
etc.

Are any of these "extra entities"?

These are not properties of space time; they are fields in space time.
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Дэйв, но это же всё ваши параметры : температура, цвет, яркость, и пр. Точно так же и с пространством-временем - это всё его свойства.
 
DaveC426913 said:
They are not properties of spacetime. They are fields that describe phenomena that exist in space.
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Дэйв, если эти ваши поля занимают одно и то же место в пространстве, в одно и то же время - то это одна и та же сущность.
 
ольга said:
Dave, if these fields of yours occupy the same place in space, at the same time, then they are the same entity.
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No they aren't.

Do you think that
1. the amount of light shining on me right now, and
2. the strength of Earth's magnetic field where I am sitting
are somehow the same entity?

Hint: No. The answer is no.
 
ольга said:
Dave, if these fields occupy the same place in space, at the same time - it's the same entity.
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Gravity 'acts' on everything equally.
The other forces only act on certain things.
To show gravity equally doing this with a bowling ball and feather.
This Youtube should open at the right time tag. 2:40
NASA vacuum chamber.

 
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foghorn said:
Gravity acts on everything equally.
Not all forces act on the same things.
To show gravity equally doing this with a bowling ball and fearther.
This Youtube should open at the right time tag. 2:40
NASA vacuum chamber.

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Ютуб в России заблокирован. Я не могу посмотреть его с этого телефона.
 
DaveC426913 said:
No they aren't.

Do you think that
1. the amount of light shining on me right now, and
2. the strength of Earth's magnetic field where I am sitting
are somehow the same entity?

Hint: No. The answer is no.
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Это разные свойства одного и того же.
 
QuarkHead said:
A field assigns a value to every point in, this case, spacetime. If the value is scalar, it's called a scalar field, if it's vector valued it's a vector field, and so on. Newtonian gravity is modelled as a scalar field, EM is modelled as a vector field, Einstein gravity is modelled as a set of tensor fields. They all are found at every point spacetime.
Click to expand...
I could be wrong on this, but wasn't it Nordstrom who tried for a scalar model of gravity? Just a couple years before GR.
 
ольга said:
These are different properties of the same thing.
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There is nothing in science that supports this.

Space does not have a "brightness" property, not does it have a "magnetism" property.

You cannot go out into deep space and capture a cube of "space" in a box and bring it home and open it up and measure the magnetic property of the "space" that's in the box. Magnetism is not a property of the "space" in the box.



The amount of light shining on me is a function of the photons streaming from the sun. If no sun, the light would be near zero.

The strength of the magnetic field where I am sitting is due to the magnetic field of the Earth. If no Earth, the magnetic field would be near zero.

This is not a matter of opinion, this is established science versus you not knowing how to science. If you want to talk about how things work in the Olgaverse, let me know and we can have this moved to Pseudoscience, where you can make up whatever you want.
 
DaveC426913 said:
There is nothing in science that supports this.

Space does not have a "brightness" property, not does it have a "magnetism" property.

You cannot go out into deep space and capture a cube of "space" in a box and bring it home and open it up and measure the magnetic property of the "space" that's in the box. Magnetism is not a property of the "space" in the box.



The amount of light shining on me is a function of the photons streaming from the sun. If no sun, the light would be near zero.

The strength of the magnetic field where I am sitting is due to the magnetic field of the Earth. If no Earth, the magnetic field would be near zero.

This is not a matter of opinion, this is established science versus you not knowing how to science. If you want to talk about how things work in the Olgaverse, let me know and we can have this moved to Pseudoscience, where you can make up whatever you want.
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Так себе аргумент. Когда то наука считала, что Земля плоская, и стоит на трёх китах. Наука - это не истина в последней инстанции, она может ошибаться. Ответьте мне тогда ещё на один вопрос: что из себя представляет ваше пространство? Пустоту? Так пустоты в природе не бывает. Тогда что?
 
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