# Vacuum VS Black Hole

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Posted (edited)

A perfect vucuum is the absence of matter in an area of space. A black hole is a super dense mass. Would you say these are the opposite of each other and if so how would you properly define their relationship? Could they be used to explain gravitational effects on a system? Would they cancel Each other out? And so on.

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Edited by Frostedwinds

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11 hours ago, Frostedwinds said:

A perfect vucuum is the absence of matter in an area of space. A black hole is a super dense mass. Would you say these are the opposite of each other and if so how would you properly define their relationship?

I would say that the opposite of a vacuum is a volume of space full of matter. A black hole is (or can be) surrounded by vacuum.

11 hours ago, Frostedwinds said:

Could they be used to explain gravitational effects on a system?

Other way round really. GR explains gravity and also explains why empty space expands and why black holes exist.

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Posted (edited)
16 hours ago, Frostedwinds said:

A perfect vucuum is the absence of matter in an area of space. A black hole is a super dense mass. Would you say these are the opposite of each other and if so how would you properly define their relationship? Could they be used to explain gravitational effects on a system? Would they cancel Each other out? And so on.

Referenced to listed pages

A BH in actual fact is nothing but critically curved spacetime, with the mass squashed at the centre at or below the quantum/Planck level. To speak of BH density is not really a valid concept.

7 minutes ago, beecee said:

A BH in actual fact is nothing but critically curved spacetime, with the mass squashed at the centre at or below the quantum/Planck level. To speak of BH density is not really a valid concept.

Let me add to that, while certainly never ever being able to observe what is inside the EH of any BH, GR does tell us that once the Schwarzchild radius is reached [which is the EH] then further collapse is compulsory. We can logically then accept that due to GR's excellent track record, that the mass continues to collapse, at least up to the quantum/Planck level where our laws of physics and GR fail us.

Edited by beecee

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Posted (edited)
3 hours ago, beecee said:

A BH in actual fact is nothing but critically curved spacetime, with the mass squashed at the centre at or below the quantum/Planck level. To speak of BH density is not really a valid concept.

Let me add to that, while certainly never ever being able to observe what is inside the EH of any BH, GR does tell us that once the Schwarzchild radius is reached [which is the EH] then further collapse is compulsory. We can logically then accept that due to GR's excellent track record, that the mass continues to collapse, at least up to the quantum/Planck level where our laws of physics and GR fail us.

Explain BH, EH, and GR please. Also let me rephrase the question them. If a perfect vacuum is space without matter. Would 1 cubic foot of a perfect vacuum act in opposition to 1 cubic foot of pure mater? Assuming you could fill one cubic foot of space with mater until it is completely full. Would they create opposing gravitational fields? Such as one inward and one outward. Negative pressure is used to create a vacuum and positive pressure is used to create condensed matter. Condensed matter creates an outward force wanting to rebalance the pressure difference and a vacuum creates an inward force wanting to rebalance the pressure difference. Gravity on the other hand seems to move matter away from a vacuum such as outer-space and toward dense matter such as a planet or sun.

Edited by Frostedwinds

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It might seem like it, but a vacuum or any region of lower pressure, doesn't create any inward force. Rather air or water at some higher pressure is pushing its way into the region.

Outside of pressures due to gravity, like atmospheric or seawater, the two are not really related.

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3 hours ago, Frostedwinds said:

Explain BH, EH, and GR please. Also let me rephrase the question them. If a perfect vacuum is space without matter. Would 1 cubic foot of a perfect vacuum act in opposition to 1 cubic foot of pure mater? Assuming you could fill one cubic foot of space with mater until it is completely full. Would they create opposing gravitational fields? Such as one inward and one outward. Negative pressure is used to create a vacuum and positive pressure is used to create condensed matter. Condensed matter creates an outward force wanting to rebalance the pressure difference and a vacuum creates an inward force wanting to rebalance the pressure difference. Gravity on the other hand seems to move matter away from a vacuum such as outer-space and toward dense matter such as a planet or sun.

One cubic ft  of perfect  vacuum would just not produce any gravity field. The cubic ft of matter would produce a gravity field with a strength depending on just how much matter there was.

There is no negative pressure involved  in making a vacuum.

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Posted (edited)
51 minutes ago, Endy0816 said:

It might seem like it, but a vacuum or any region of lower pressure, doesn't create any inward force. Rather air or water at some higher pressure is pushing its way into the region.

Outside of pressures due to gravity, like atmospheric or seawater, the two are not really related.

Why is a vacuum measured in a negative pressure then? Doesn’t that mean there is an inward force being generated by the need to balance the pressure variance of the space around a vacuum and the space inside a vacuum?

49 minutes ago, Janus said:

One cubic ft  of perfect  vacuum would just not produce any gravity field. The cubic ft of matter would produce a gravity field with a strength depending on just how much matter there was.

There is no negative pressure involved  in making a vacuum.

A vacuum is measured in negative pressure. Wouldn’t that suggest it’s creating an opposing force to that of a gravitational field generated by solid matter?

Edited by Frostedwinds

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Posted (edited)
18 minutes ago, Frostedwinds said:

Why is a vacuum measured in a negative pressure then? Doesn’t that mean there is an inward force being generated by the need to balance the pressure variance of the space around a vacuum and the space inside a vacuum?

For a system like psig(pounds per square inch gauge), you are considering atmospheric pressure to be Zero. Any pressure below that would then take on a negative value.

Something like psia or pascals is easier to consider.

You can see that with: Pressure = Force/Area

Pressure can only be zero if the Force is zero.

Edited by Endy0816

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7 hours ago, Frostedwinds said:

Explain BH, EH, and GR please.

Black hole.

Event horizon

Gneeral relativity

7 hours ago, Frostedwinds said:

Also let me rephrase the question them. If a perfect vacuum is space without matter. Would 1 cubic foot of a perfect vacuum act in opposition to 1 cubic foot of pure mater? Assuming you could fill one cubic foot of space with mater until it is completely full. Would they create opposing gravitational fields?

The vacuum would create no gravitation (because it has no mass). The cubic foot of matter would create a gravitational field depending on its mass: 1 cubic foot of hydrogen has much less mass (2.5 grams) than 1 cubic foot of osmium (640 kg).

7 hours ago, Frostedwinds said:

Condensed matter creates an outward force

If it is a gas at higher pressure than its surroundings, Male. But not in general.

7 hours ago, Frostedwinds said:

Gravity on the other hand seems to move matter away from a vacuum such as outer-space and toward dense matter such as a planet or sun.

Massive objects attract one another.

Although it is not quite that simple. A completely even distribution of mass will either expand or contract.

3 hours ago, Frostedwinds said:

Why is a vacuum measured in a negative pressure then?

It depends on how it is measured. It is only negative if you use a relative pressure gauge. When I did a little bit of vacuum physics, a perfect vacuum was a pressure of zero. The pressure we actuallyachieved would be positive.

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10 hours ago, Frostedwinds said:

Why is a vacuum measured in a negative pressure then? Doesn’t that mean there is an inward force being generated by the need to balance the pressure variance of the space around a vacuum and the space inside a vacuum?

A vacuum is measured in negative pressure. Wouldn’t that suggest it’s creating an opposing force to that of a gravitational field generated by solid matter?

As already mentioned,  a "negative " pressure reading just means that you are reading the pressure relative to a chosen value,  like one standard atmosphere.  In absolute measurement,  1 atm is a out 14 psi.  It is like measuring altitude,  we measure it relative to mean sea level, and can get below sea-level values, but even sea level is thousands  of miles higher than the center of the Earth.  So no, vacuums do not create any information ward force.

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8 hours ago, Strange said:

Black hole.

Event horizon

Gneeral relativity

The vacuum would create no gravitation (because it has no mass). The cubic foot of matter would create a gravitational field depending on its mass: 1 cubic foot of hydrogen has much less mass (2.5 grams) than 1 cubic foot of osmium (640 kg).

If it is a gas at higher pressure than its surroundings, Male. But not in general.

Massive objects attract one another.

Although it is not quite that simple. A completely even distribution of mass will either expand or contract.

It depends on how it is measured. It is only negative if you use a relative pressure gauge. When I did a little bit of vacuum physics, a perfect vacuum was a pressure of zero. The pressure we actuallyachieved would be positive.

Thank you for the explanation of BH, EH and GR. So if a perfect vacuum is a completely neutral state with no gravity, then what kind of physics are still present in a perfect vacuum if any. I’ve seen people talk about what happens when you introduce matter to a vacuum but what about if you introduced an area of a perfect vacuum into a pre existing system like a tank of water. Also a perfect vacuum is a neutral state so then what is a negative state. Also is there any existing area where a vacuum wouldn’t have relative negative pressure in the universe. Even outer-space still has more matter in it then a perfect vacuum.

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1 hour ago, Frostedwinds said:

So if a perfect vacuum is a completely neutral state with no gravity,

I would change "no gravity" in this instance to "no gravitational influence of its own". If you had such a vacuum, and suddenly introduced matter into it, it would still be affected by spacetime curvature from any nearby massive objects. I'm being nit-picky, but "not generating any gravity in the area of a vacuum" is different from "gravity doesn't affect the area inside a vacuum", so I wanted to make sure of what you meant by "no gravity".

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2 hours ago, Frostedwinds said:

I’ve seen people talk about what happens when you introduce matter to a vacuum but what about if you introduced an area of a perfect vacuum into a pre existing system like a tank of water.

The water would rush to fill the empty space. This would be an extreme form of cavitation: https://en.wikipedia.org/wiki/Cavitation

2 hours ago, Frostedwinds said:

Also a perfect vacuum is a neutral state so then what is a negative state.

There is no negative state, in terms of mass or energy (or the presence of matter).

2 hours ago, Frostedwinds said:

A﻿lso is there any existing area where a vacuum wouldn’t have relative negative pressure in the universe. Even outer-space still has more matter in it then a perfect vacuum.

No. A (perfect) vacuum is zero mass (and energy). There is nothing less than that.

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21 hours ago, Frostedwinds said:

Explain BH, EH, and GR please. Also let me rephrase the question them. If a perfect vacuum is space without matter. Would 1 cubic foot of a perfect vacuum act in opposition to 1 cubic foot of pure mater? Assuming you could fill one cubic foot of space with mater until it is completely full. Would they create opposing gravitational fields? Such as one inward and one outward. Negative pressure is used to create a vacuum and positive pressure is used to create condensed matter. Condensed matter creates an outward force wanting to rebalance the pressure difference and a vacuum creates an inward force wanting to rebalance the pressure difference. Gravity on the other hand seems to move matter away from a vacuum such as outer-space and toward dense matter such as a planet or sun.

Sorry, I've been a rather busy little beaver. Others have explained the BH, EH and GR correctly. Secondly all matter/energy warps or affects the geometry of flat spacetime, [it curves, warps, twists spacetime] and we feel that geometry as gravity. So any perfect vacuum, that is space without any light or any form of energy would be perfectly flat.

The only possible perfect vacuum state I think [willing to be corrected on this] is inside the EH of a dormant BH, that has obtained perfect temperature equilibrium with the outside.

And while this is certainly curved by the collapsed mass at the core, it does not  "no gravitational influence of its own" to pinch the phrase from Phi for All.

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Pressure, as commonly understood, is not easily related to General Relativity.

However, if we think of space-time as a coiled spring, it is easy to understand that if you compress that spring, you increase its energy, and the curvature of space-time around it.
An easy to understand excerpt from
https://ned.ipac.caltech.edu/level5/Guth/Guth3.html
explains the relationship between pressure, energy density, space-time curvature ( gravity ) and expansion/inflation.

"THE PRESSURE OF THE FALSE VACUUM can be determined by a simple energy-conservation argument. Imagine a chamber filled with false vacuum, as shown in the diagram below.

The pressure is negative, and extremely large. General relativity predicts that the gravitational field which slows the expansion of the universe is proportional to uf + 3p, so the negative pressure of the false vacuum overcomes the positive energy density to produce a net repulsive gravitational field. "

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5 hours ago, Phi for All said:

I would change "no gravity" in this instance to "no gravitational influence of its own". If you had such a vacuum, and suddenly introduced matter into it, it would still be affected by spacetime curvature from any nearby massive objects. I'm being nit-picky, but "not generating any gravity in the area of a vacuum" is different from "gravity doesn't affect the area inside a vacuum", so I wanted to make sure of what you meant by "no gravity".

If a perfect vacuum is an isolated system the effects of its interaction with mater isn’t possible because it no longer would stay a perfect vacuum. So a perfect vacuum, being unable to interact with matter without undergoing a state change to an imperfect vacuum, would by its self have no gravity inside of its system. It would be neutral space without any gravitational field or any ability to interact with gravity.

4 hours ago, Strange said:

The water would rush to fill the empty space. This would be an extreme form of cavitation: https://en.wikipedia.org/wiki/Cavitation

There is no negative state, in terms of mass or energy (or the presence of matter).

No. A (perfect) vacuum is zero mass (and energy). There is nothing less than that.

If there is no negative state of mass and energy than a balanced system would display an area of absolute mass and energy to be the contrast to a perfect vacuum. What effects on a system would result from combining these two.

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Posted (edited)

Mass and energy are two properties that are in essence the same thing. Consider  that mass is resistance to inertia change. Energy is the ability to perform work. Then further consider $e=mc^2$. One can readily see the two are readily interchangeable.

If you combine an over dense region into an underdense region then the two regions will reach an equilibrium state  the sum of the two parts.

However blackholes also has extremely strong gravity so this process could take longer than the age of our universe. See black hole evaporation via Hawking radiation. In this scenario the universe Blackbox temperature of a near perfect vacuum will be less than the black body temperature of the BH. This is the only time Hawking radiation can occur. If opposite the BH will gain mass instead of losing it.

Edited by Mordred

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2 hours ago, beecee said:

Sorry, I've been a rather busy little beaver. Others have explained the BH, EH and GR correctly. Secondly all matter/energy warps or affects the geometry of flat spacetime, [it curves, warps, twists spacetime] and we feel that geometry as gravity. So any perfect vacuum, that is space without any light or any form of energy would be perfectly flat.

The only possible perfect vacuum state I think [willing to be corrected on this] is inside the EH of a dormant BH, that has obtained perfect temperature equilibrium with the outside.

And while this is certainly curved by the collapsed mass at the core, it does not  "no gravitational influence of its own" to pinch the phrase from Phi for All.

If an area of perfect vacuum has no mass or energy, how does that affect the relativity of how many dimensions it posses. Also if it did change the amount of dimensions the area of perfect vacuum would have, wouldn’t it be more likely that it would lose all dimensions and become a singular point instead of infinitely flat. That would also be closer to the effects of EH displays no gravitational influence of its own. Considering a perfect vacuum an area of space without matter would suggest that while in practice it may be closer to and EH with less dimensional properties, but in an isolated system it would be able to be any space within the three dimension of space that matter and energy doesn’t exist.

4 minutes ago, Mordred said:

Mass and energy are two properties that are in essence the same thing. Consider  that mass is resistance to inertia change. Energy is the ability to perform work. Then further consider $e=mc^2$. One can readily see the two are readily interchangeable.

If you combine an over dense region into an underdense region then the two regions will reach an equilibrium state  the sum of the two parts.

However blackholes also has extremely strong gravity so this process could take longer than the age of our universe. See black hole evaporation via Hawking radiation.

That’s what I was first assuming. That an area without matter being a density of 0 and an area with absolute matter being a density of ♾ then the interaction would be a state of equilibrium. Just like mass and energy in a system together such as e=mc^2 are in opposition but essential the same. They create a balanced system.

2 hours ago, MigL said:

Pressure, as commonly understood, is not easily related to General Relativity.

However, if we think of space-time as a coiled spring, it is easy to understand that if you compress that spring, you increase its energy, and the curvature of space-time around it.
An easy to understand excerpt from
https://ned.ipac.caltech.edu/level5/Guth/Guth3.html
explains the relationship between pressure, energy density, space-time curvature ( gravity ) and expansion/inflation.

"THE PRESSURE OF THE FALSE VACUUM can be determined by a simple energy-conservation argument. Imagine a chamber filled with false vacuum, as shown in the diagram below.

The pressure is negative, and extremely large. General relativity predicts that the gravitational field which slows the expansion of the universe is proportional to uf + 3p, so the negative pressure of the false vacuum overcomes the positive energy density to produce a net repulsive gravitational field. "

So a perfect vacuum would be a state of negative pressure inside a system. Still considering it to be neutral while isolated outside of a system. Inside a system it would create a negative gravitational field. Absolute mass would then generate a state of positive pressure inside a system. Which brings to question if it also is neutral while isolated outside of a system. Inside of a system it creates a positive gravity field. So a perfect vacuum and absolute mass are resting in perfect opposition to each other.

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Posted (edited)

Ok let's do a quick terminology change. The reason being in QM perfect vacuums are hypothetically impossible. A type of vacuum devoid of all mass/energy including virtual particles is an Einstein vacuum. Once again it's a hypothetical vacuum state but it's a GR class of solutions.

Also you can have any volume with this vacuum state which under GR is still 4d. It is incorrect to think that an Einstein vacuum means a loss of spatial and time dimensions.

Keep in mind a dimension vin physics as well as mathematics is any independent quantity/variable or any other mathematical object.

The x,y,z,ct coordinates count as such. For example the value of x can change without changing the value of any other coordinate.

It is best to keep these definitions in mind whenever your discussing physics as they apply to all physics theories.

The term dimension and degree of freedom are interchangeable.

It may sound like not picking but you will find this useful in understanding theories that employ higher dimensions.

4 hours ago, MigL said:

Pressure, as commonly understood, is not easily related to General Relativity.

Can't cut the image out but not important. On GR pressure is tricky to understand here is a simple to understand guide to how the stress energy tensor handles pressure in terms of flux.

This guide is a good stepping stone into the EFE. Einstein field equation. It also highlights several of the topics mentioned in this thread so far

Edited by Mordred

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7 hours ago, Frostedwinds said:

If﻿ a perfect vacuum is an isolated system the effects of its interaction wi﻿th mater isn’t possible because it no longer would stay a perfect vacuum. So a perfect vacuum, being unable to interact with matter without undergoing a state change to an imperfect vacuum, would by its self have no gravity inside of its system. It would be neutral space without﻿ any g﻿ravitation﻿al field or any ability to interact with gravity.﻿

You are talking about vacuum as if it were a thing; it isn’t, it’s just an absence of stuff.

6 hours ago, Frostedwinds said:

If﻿ an area of perfect vacuum has no mass or energy, how does that﻿﻿﻿﻿﻿﻿﻿﻿ affect the re﻿l﻿ativity of how many dimensions ﻿i﻿t ﻿poss﻿es.﻿

You are talking about a cubic foot, so it has 3 dimensions. The presence or absence of matter doesn’t change that.

Your comparison with an event horizon doesn’t really make sense.

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On 7/20/2019 at 3:28 AM, Strange said:

You are talking about vacuum as if it were a thing; it isn’t, it’s just an absence of stuff.

You are talking about a cubic foot, so it has 3 dimensions. The presence or absence of matter doesn’t change that.

Your comparison with an event horizon doesn’t really make sense.

Beecee was talking about how a perfect vacuum would most likely be perfectly flat and display effects similar to an EH. I was questioning why he stated that. Your question would probably be better suited for Beecee.

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14 minutes ago, Frostedwinds said:

Beecee was talking about how a perfect vacuum would most likely be perfectly flat and display effects similar to an EH. I was questioning why he stated that. Your question would probably be better suited for Beecee.

Not exactly.  And remember beecee is a human entity and could be wrong and open to correction.

What I said was....

On 7/20/2019 at 7:48 AM, beecee said:

Sorry, I've been a rather busy little beaver. Others have explained the BH, EH and GR correctly. Secondly all matter/energy warps or affects the geometry of flat spacetime, [it curves, warps, twists spacetime] and we feel that geometry as gravity. So any perfect vacuum, that is space without any light or any form of energy would be perfectly flat.

The only possible perfect vacuum state I think [willing to be corrected on this] is inside the EH of a dormant BH, that has obtained perfect temperature equilibrium with the outside.

And while this is certainly curved by the collapsed mass at the core, it does not  "no gravitational influence of its own" to pinch the phrase from Phi for All.

What that is saying is the  EH marks the parameter of a collapsed mass that has surpassed its Schwarzchild limit and where the escape velocity equals "c". If the BH is not consuming any matter/energy, then the region inside the EH and up to the quantum/Planck level where we believe the mass and all energy has reached, will then be a perfect vacuum, but also highly curved, [due to the mass/energy at the core]  but obviously as highlighted, with no gravitational influence of its own.

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25 minutes ago, beecee said:

And remember beecee is a human﻿﻿﻿﻿﻿﻿﻿ entity and coul﻿d be wrong an﻿d open to c﻿orrecti﻿on.﻿

Did you really just refer to yourself in the third person?

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31 minutes ago, Bufofrog said:

Did you really just refer to yourself in the third person?

Probably, why?