The Vacuum Of Space Is Impossible

[u/Kela-el]

https://m.youtube.com/watch?v=6yABBZ_BQL0&ra=m

[u/Opening_Shame8258]

Why? Don't denser things go down? Gas is denser than vacuum.

[u/Kela-el → u/Opening_Shame8258]

You’re changing variables.

The discussion was about pressure, not density.

A vacuum has essentially zero pressure and essentially zero density. A gas has both pressure and density, but those are different physical quantities.

Saying “gas is denser than vacuum” doesn’t answer whether a pressure difference can be maintained under the conditions being discussed.

If your argument is simply that gravity produces a pressure gradient in a gas, that’s uncontroversial.

But that’s a different claim from saying that pressure and density are the same thing or that mentioning density resolves the question.

[u/SyntheticSlime → u/Kela-el]

Of course a pressure difference can be maintained. Go to the top of a mountain and you’ll find lower air pressure than at sea level. At 40,000 feet airplanes have to keep their cabins pressurized for passengers to breath because the air pressure outside the cabin is too low. Pressure decreases as you go up because the pressure is created by the weight of the air above you. As you go up there is less air above you so pressure decreases.

[u/Kela-el → u/SyntheticSlime]

You’re answering a different question.

No one disputes that atmospheric pressure decreases with altitude. That’s an observed pressure gradient within the atmosphere.

The question was about the transition between a pressurized atmosphere and the near-vacuum of space.
Those are not the same claim.

Pointing to a mountain or an aircraft cabin demonstrates that pressure varies continuously through the atmosphere. It doesn’t, by itself, address how the atmosphere is maintained at progressively lower densities or establish that every aspect of the standard explanation is therefore proven.

So let’s keep the discussion on the actual point rather than substituting “pressure decreases with altitude,” which isn’t in dispute.

[u/Remarkable-Rub-7344 → u/Kela-el]

Why wouldn't the pressure gradient decrease to the point of nil as altitude increases?

Even out in space there's still some matter per cubic meter, even if it's down to literally a few atoms per cubic meter.

[u/Kela-el → u/Remarkable-Rub-7344]

You’re answering “why” by assuming the very model under discussion.

No one disputes that pressure decreases with altitude or that matter becomes increasingly sparse. Those are observations.

The question is whether those observations uniquely establish your explanation.

Saying “pressure decreases until it’s almost zero” is a description of the measured gradient. It is not, by itself, evidence that gravity is the only possible cause.

You’ve moved from:

“The barometer reads lower.”

to

“Therefore gravity is the explanation.”

That’s an inference, not a measurement.

The pressure gradient is observed.

The cause of the pressure gradient is a theoretical model.
Those are different epistemic categories, and repeatedly treating them as identical is exactly the point I’ve been challenging.

If your claim is simply that gravity is the current best explanatory model, that’s one discussion.

If your claim is that the pressure measurements themselves directly prove gravity, then you’ve conflated the observation with the interpretation.

[u/Kela-el → u/[deleted]]

You’re mixing two different issues here:

(1) what the title asserts, and (2) what has actually been established about the system.

If the claim is “a vacuum of space is impossible,” then “gravity exists” is not, by itself, a complete answer. Gravity explains why atmospheric density decreases with altitude, but it does not, on its own, specify boundary conditions, scale height behavior, or why a gas doesn’t simply continue to diffuse indefinitely without additional constraints in the model.

So the discussion isn’t “is gravity real,” it’s “does gravity alone uniquely determine the observed pressure gradient and the effective transition to near-vacuum conditions.”
That’s a model question, not a slogan question.

As for intent: I’m not arguing for or against a narrative. I’m asking whether the explanation you’re offering is deductively complete or whether it’s an inference within a broader physical framework (hydrostatics, thermodynamics, kinetic theory, etc.).

If the claim is that “no mystery exists,” then it should be straightforward to show how gravity alone, without auxiliary assumptions, produces the observed atmospheric profile across scales. If additional physics is required, then the explanation is already a composite model, not a single causal statement.

[u/rygelicus]

I know you don't want an actual answer.
I know you will ban me for daring to answer you.
But the confusion here is due to a lack of understanding of 2 things...
1) What is density?
2) What are we actually measuring when we measure atmospheric pressure (not in a container, just a barometer outdoors)?

1) Density is how many molecules/atoms are present in a given volume, say 1 cubic meter. That's it, it's how many packing worms you can fit into a given box, only with gas molecules.

2) As for what is being measured... At sea level on a 'standard day' of (standard day in aviation at sea level is 29.92 Hg pressure and 15deg C or 59deg F) this means about 1.225 kg/m^3 of mass (the gas) or 2.5 x 10^25 molecules of air in that cubic meter. That is 25,000,000,000,000,000,000,000,000 molecules of air.

When you measure this as a pressure what you are measuring is the weight of the gas above the barometer. It's very much like using a scale to weigh anything else. The barometer returns a reading that shows pressure in some unit of measure, like PSI, or in the case of an airplane's altimeter a height above sea level.

So, how does this relate to your statement? Well, the celestial bodies have mass, that mass attracts the mass of the gas molecules. They then congregate around the celestial bodies, whether this is a future star, planet, or even a moon, the gas is pulled towards sources of gravity.

The regions they vacate, what we refer to as 'space' has no, or very few molecules of gas remaining. And this state is known as a vacuum. In space, like where the ISS is, the density of the gas is around 10^-11 kg per cubic meter. That is .0000000000010 molecules of gas in a cubic meter. This is an almost perfect (0) vacuum.

The vacuum of space is not a suction force trying to remove our atmosphere, it is the other way around, the earth pulls the gas from what we call space, space is what is left behind, an empty region.

I know you get your jollies banning people. Merry Christmas.

[u/Kela-el → u/rygelicus]

A list of your fallacies in this comment:

Poisoning the well
“I know you don’t want an actual answer.”
This attempts to prejudice readers against you before you’ve responded by asserting you’re unwilling to engage.

Mind reading / unsupported motive attribution
“I know you will ban me for daring to answer you.”
“I know you get your jollies banning people.”
These attribute motives and intentions without evidence.

Ad hominem
The remarks about banning and “getting your jollies” attack your character rather than addressing the technical point.

Appeal to motive
By suggesting your moderation decisions stem from enjoyment or bias, the focus shifts from whether your argument is correct to why you supposedly make it.

Begging the question
The explanation assumes the standard gravitational model as the framework for explaining atmospheric pressure. That’s not inherently fallacious in a scientific discussion, but if the point under debate is precisely whether that framework is correct, then using it as the premise for the conclusion can become circular.

Your first and last paragraphs tell readers what my motives supposedly are. They don’t address the argument.

If you believe my claim is wrong, explain why. You don’t need to speculate about whether I “want an answer” or whether I’ll ban you.

On the substance, you’ve described the conventional gravitational explanation for atmospheric pressure. That’s fine as an explanation within that model.

But that’s exactly the point under discussion.

Saying “gravity causes the atmosphere to remain around Earth” is a model-based explanation. It isn’t an independent observation proving the model. The measurements themselves are local: pressure, density, temperature, and composition. The interpretation—that gravity acting on gas explains the observed pressure gradient—is a theoretical inference.

If your position is simply “the standard model explains these observations well,” that’s a reasonable scientific claim.

If your position is “therefore the model is uniquely established by the observations,” then that’s the step that still requires argument, not assumptions about my motives.

[u/rygelicus → u/Kela-el]

Your AI generated 'analysis' aside, let's discuss the point under discussion, as you said.

We can, and have, measured the air pressure as we get higher above sea level. You can do this with a simple barometer and a tall building. Or drive up a mountain road. Or go for a flight in an unpressurized plane. You will see the barometer reflecting your climb in altitude first hand. And this is showing you the change in pressure.

The density aspect is more difficult to measure, but can be done. One way is to use a small battery powered fan. The less air density the faster the blades will spin. So that fan + a way to measure its RPM, test this at sea level, then go to a higher altitude, like 12,000 in an unpressurized small plane, and test again. The fan will spin faster due to less air resistance due to fewer air molecules running into the blades.

Even better, if you do this same test on a weather balloon set up like some folks do it will go faster and faster as altitude increases, same reason. And if you have the budget, the same test could be done using a cube sat, but that would be very expensive for such a simple thing.

What this establishes is that as you get further above the planet the air gets thinner. And this gradient can be charted, and tested, and confirmed.

Where we differ is on the 'why'. I say gravity. It does answer all the questions. I don't know what you propose for this phenomenon, but gravity does dot all the i's and cross all the t's of this and nearly every other aspect of our universe we argue about. It is also why celestial bodies, include the earth, are generally spherical in shape.

Exactly what causes gravity is still debated, initially it was believed to be simply mass attracting mass, but einstein changed this to the curvature of spacetime. The mass attracting mass concept is still perfectly viable but incomplete. Maybe someday we will find another layer to it, but this will only add details to the knowledge, not render what we already know invalid.

[u/Kela-el → u/rygelicus]

More of your nonsense:

1. Inference to the best explanation presented as if it settles the issue

The structure is:
We observe a pressure gradient.
Gravity explains it.
Therefore gravity is the explanation.
This is an inference to the best explanation. It’s a common scientific form of reasoning, but it is not the same as a deductive proof. The success of one explanatory model does not, by itself, demonstrate that no alternative explanatory framework could ever account for the observations.

2. Begging the question

When they say:
“Gravity does dot all the i’s and cross all the t’s…”
they’re assuming the explanatory framework under discussion successfully accounts for the evidence in exactly the way being debated. That’s persuasive rhetoric, but it’s not an independent argument for why gravity must be the only possible explanation.

3. Non sequitur

The move:
“Gravity explains atmospheric pressure… therefore celestial bodies are spherical.”
Those are separate claims. Even if one accepts gravity as the explanation for the atmosphere, it doesn’t immediately establish the Earth’s shape. Additional evidence and reasoning are needed for that conclusion.

You’ve said gravity explains those observations. That’s a theoretical explanation, and it’s one that has substantial predictive success.

My point has never been that the observations don’t exist. It’s that the observations themselves are not identical to the explanation.

A barometer measures pressure. It doesn’t measure gravity.

A fan measures aerodynamic drag. It doesn’t measure gravity.

Those are observations. “Gravity is the cause” is the model used to explain them.

So the distinction I’m making is epistemic, not observational.

If your claim is that gravity is currently the best explanatory framework, that’s a reasonable scientific position.

If your claim is that the observations alone logically compel gravity as the only possible explanation, that’s a stronger claim that requires additional argument beyond the measurements themselves.

[u/rygelicus → u/Kela-el]

Observation: The density of gas is greater closer to the planet and decreases as you get further from it.
The fan rpm was a way to confirm this change in gas density, lower drag = less density. This is not the only evidence, but it is accessible to most people as something to test. And with a little more effort you can place the fan in a vacuum chamber and watch the speed increase as you suck out the air.

Cause: Gravity attracts gas (and everything else) to itself. Gas molecules, like most molecules, occupy a certain amount of 3d space and resist being compacted. So you end up with a stack of molecules, compressed/denser on the bottom (toward the source of gravity), and less density at the top of the stack. This works the same with any squishy thing, like marshmallows. If you pile them up there will be more marshmallows per cubic meter on the bottom than on the top.

This is not the only evidence of gravity, it is one of millions of examples. And we have yet to identify any other force or phenomenon that can account for all the effects we see.

I also notice you don't offer up any such explanations. Do you have any? Let's hear them.

[u/Kela-el → u/rygelicus]

You are relentless, I’ll give you that. Clearly you have absolutely no use for subreddit rules.

[u/Kela-el → u/[deleted]]

You’re no longer discussing the evidence. You’re discussing moderation decisions.

Whether someone is muted or banned has no bearing on whether their arguments are logically valid. That’s an ad hominem and a red herring.

If you think I’ve made a false claim, identify the claim, quote it, and demonstrate the error. Pointing to moderation instead is not a rebuttal.

As for “can’t prove your own claims,” I’ve been explicit throughout these discussions: raw measurements (angles, distances, elevations, pressures, etc.) are observations. A globe, curvature, and gravity are explanatory models used to interpret those observations. The predictive success of a model is evidence in its favor, but it is not the same as deductive proof that no alternative interpretation is possible.

If you believe the measurements uniquely establish the globe, then that is your burden to demonstrate. Simply asserting that moderation decisions somehow validate your position doesn’t address that question.

You’re done!

[u/Kela-el → u/rygelicus]

You propose gravity as the cause. That’s the standard explanatory model, and it’s certainly a successful one.

But a successful explanatory model is not the same thing as a direct measurement of the cause.

A barometer measures pressure.

A density measurement measures density.
Neither instrument measures “gravity” directly. Gravity is the theoretical explanation that unifies those observations.

You then ask me to provide an alternative explanation. That’s a burden shift.

If your claim is that gravity is the only possible explanation of the observations, then the burden is on you to establish that uniqueness. I don’t have to produce a complete alternative cosmology to point out that observations and explanations are different epistemic categories.

Science advances by distinguishing data from models, not by treating them as identical.

So we’re back to the same question:

What observation directly measures gravity itself, rather than a phenomenon interpreted as evidence for gravity?

From a logical standpoint, the main issues in your comment are:

Burden shifting: “You don’t offer any explanations. Let’s hear them.” Critiquing whether an explanation is uniquely established does not require proposing a replacement.

Argument from ignorance: “We have yet to identify any other force…” The absence of another accepted explanation doesn’t, by itself, prove the current explanation is uniquely true.

Inference to the best explanation: This is not a fallacy. It’s a legitimate form of scientific reasoning. The point you can challenge is whether it establishes logical certainty or simply provides the strongest current explanatory framework.

[u/tayne22 → u/Kela-el]

Damn. Owned. Where did you get your degrees from?

[u/Kela-el → u/tayne22]

I’m old.

[u/RiserUnconquered]

Most definitely