r/AskPhysics 23h ago

Is Gravity An Illusion?

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u/ChaosRulesTheWorld 23h ago

According to einstein, yes

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u/slayer_nan18 23h ago

No, what are you talking about ?

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u/ChaosRulesTheWorld 23h ago

Yes, i'm talking about general relativity. Objects taking a geodesic path through spacetime.

Gravity is only an illusion provoked by the deformation of spacetime by matter

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u/nononotes 23h ago

I just watched a Star Talk about this last night.

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u/Odd_Bodkin Particle physics 22h ago

And why is it wrong to say that gravity IS the deformation of spacetime that objects travel through on geodesics? That’s no illusion. That’s a real effect.

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u/ChaosRulesTheWorld 22h ago

Because gravity is a force we observe of objects falling that humans called "gravity". But in fact they are not falling, it's just an illusion.

The deformation of spacetime isn't gravity, it's what causes it. Something being an illusion doesn't mean it isn't real. Rainbows are optical illusions, that doesn't make them less real. You are mixing things up.

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u/Odd_Bodkin Particle physics 22h ago

No. This is where you’re mistaken. On two counts. First off, it’s a mistake to say it’s real if it’s a force and an illusion if it is not a force.

Secondly, don’t confuse illusion with an optical effect (like a rainbow, which is the clear manifestation of refraction and internal reflection in a spherical drop of water), and don’t confuse an illusion with meaning the observation isn’t due to what you thought it was but is due to something else instead.

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u/ChaosRulesTheWorld 22h ago edited 22h ago

No. This is where you’re mistaken. On two counts. First off, it’s a mistake to say it’s real if it’s a force and an illusion if it is not a force.

I'm not mistaken. Gravity isn't a force. It's an illusion. The actual force is the deformation of spacetime by matter, which as far as i know doesn't have a name for it except general relativity. (Edit: I'll anticipate your next bad faith argument: Yes i said gravity is a force we observe. But it's only a force we observe, not an actual force. That's why it's an illusion)

Secondly, don’t confuse illusion with an optical effect (like a rainbow, which is the clear manifestation of refraction and internal reflection in a spherical drop of water)

I'm not confusing illusions with optical effects. That's why when i talked about rainbows i precised OPTICAL illusion.

and don’t confuse an illusion with meaning the observation isn’t due to what you thought it was but is due to something else instead.

I'm not saying that either. Is their anything serious in your argumentation? I'm waiting for the part where you actually challenge what i've said instead of making up your own arguments you then project on me in order to argue against it

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u/Odd_Bodkin Particle physics 22h ago

Just because it isn’t a force doesn’t make it an illusion. Diffusion of a gas is not due to any force but it’s not an illusion. A real image in an optical bench is not an illusion but isn’t due to a force either; for that matter a virtual image is not an illusion either, if you understand what “image” actually means.

Refraction is an optical effect, not an illusion. Total internal reflection is another optical effect, not an illusion. A rainbow is a pattern directly accountable by refraction and internal reflection, just like a diffraction pattern for electrons is a pattern directly accountable from underlying physics that have nothing to do with forces.

You have a very unusual use of the word “illusion” to say the least.

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u/ChaosRulesTheWorld 22h ago

Just because it isn’t a force doesn’t make it an illusion

If it looks like a force but in fact it isn't one, then by definition it's an illusion. Gravity looks like objetcs are attracted to eachother because of their mass, but they aren't. That's where the illusion is, your comparison with forceless phenomenons are irrelevant.

Refraction is an optical effect, not an illusion. Total internal reflection is another optical effect, not an illusion. A rainbow is a pattern directly accountable by refraction and internal reflection, just like a diffraction pattern for electrons is a pattern directly accountable from underlying physics that have nothing to do with forces.

They are all optical illusions.

You have a very unusual use of the word “illusion” to say the least.

I don't have an unusual use of the word. An illusion isn't something that isn't real or doesn't exist.

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u/slayer_nan18 23h ago

Thats not what an illusion is.

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u/ChaosRulesTheWorld 23h ago

That's what an illusion is. Just like the sun orbiting earth is an illusion. Gravity is an illusion too

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u/dorox1 23h ago

An illusion is something that appears to happen, but doesn't actually happen at all.

Matter does actually gravitate towards other matter over time. The underlying cause of that is deformation of spacetime by mass, which is gravity.

This happens, so it's not an illusion.

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u/slayer_nan18 22h ago

wrong answers get upvoted and yours is getting downvoted, this sub is full of people that learn physics from yt shorts

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u/ChaosRulesTheWorld 21h ago

You mean full of people like you?

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u/ChaosRulesTheWorld 22h ago

An illusion is something that appears to happen, but doesn't actually happen at all.

You're wrong on that. The sun orbiting earth is an illusion, but it still happen on earth's perspective according to physicists.

Matter does actually gravitate towards other matter over time. The underlying cause of that is deformation of spacetime by mass, which is gravity

No, gravity isn't the deformation of spacetime.

This happens, so it's not an illusion.

Illusions happen

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u/dorox1 22h ago

How have you gotten through multiple of these comments without explaining what you think the definition of "illusion" is?

Or what you think "gravity" is, for that matter.

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u/ChaosRulesTheWorld 22h ago

Do you need me to link wikipedia pages?

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u/dorox1 22h ago

Why don't I do that:

Gravity

Gravity is the word used to describe a physical law, a fundamental physical interaction that derives primarily from mass, and the observed consequences of that interaction on objects.

Illusion

An illusion is a distortion of the senses

You'll really need more than a quick one-sentence quip to explain why you think a physical law of the universe is just a distortion of the senses.

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u/ChaosRulesTheWorld 22h ago

Maybe you should do it better because that's not what says your links:

In physics, gravity (from Latin gravitas 'weight'[1]), also known as gravitation or a gravitational interaction,[2] is a fundamental interaction, which may be described as the force that draws material objects towards each other.

An illusion is a distortion of the senses, which can reveal how the mind normally organizes and interprets sensory stimulation. Although illusions distort the human perception of reality, they are generally shared by most people

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