# Physics and science, just man made idea?

#### 27Thousand

What "actual reality"? You think Newton had some deeper, qualatative description of gravity independent of the math? He didn't. I think you misunderstand what science is....
Gravitational force is a force. It says so right in Newton's gravitational force equation and as DH explained, that equation is still perfectly valid in a large number of applications!
Thought experiment and back up from educational sources:

If I'm in a car going around a corner very quickly, I get pushed to the side. That's not because there's an external force in the curb pulling on me, but rather that my body wants to move in a straight line unless acted upon by an outside force. Einstein said gravitation is the same as acceleration rather than an external force, gave his rocket on the ground vs. space thought experiment, and it's been tested. How do you explain the studies for the equivalence principle, inertial mass and gravitational mass? Einstein's Gravitation being a fictitious force, or the bending of spacetime creating an illusion of an external force? Link from UCLA http://www.physics.ucla.edu/demoweb/demomanual/modern_physics/principal_of_equivalence_and_general_relativity/curved_spacetime.html You're not implying that at slow speeds and low mass, gravitation is an external force field, while in other situations it's instead the bending of spacetime? I thought gravitation is gravitation. That's why I said the implications stayed similar, although the explanation was replaced (physical laws vs. what a scientific theory is).

If Newton's idea that gravitation is a force was real, how do you explain gravitational redshift, gravitational time dilation, the wobble of Mercury's orbit, stuff that happens with black holes, and how the bending of light is not what Newton would predict but rather what Einstein would? Newton said a body at rest stays at rest unless an external force does something, so according to him if I'm holding an apple and drop it, the reason it doesn't stay at rest is because of an external force called gravity. However Einstein said it was the bending of spacetime with no force involved, just acceleration plus the bending of spacetime create the illusion.

Something I found from the National Academy of Sciences, the highest Science organization in the U.S. http://books.nap.edu/openbook.php?record_id=751&page=8

Another source says: "The general theory overturned Newton's theory of gravity which had been valid for two hundred and fifty years. In Newton's universe, gravity was regarded as an attractive force which all massive bodies exert on each other. The planets moved in elliptical orbits about the sun because of its great mass powerful gravitational force. In Einstein's universe, gravity is not regarded as an exterior force, but rather as a property of space and time or "spacetime"."
http://www.alberteinstein.info/gallery/gtext3.html [Broken]

If Newton's laws are completely correct in a given situation, wouldn't that make them Absolute Truth for that limited situation?
The observable principle may be correct for that limited situation. However, does that mean the observable principle law is universal (correct), nor even the explanation (theory of gravitation)? Aristotle's theory of gravitation was right in some situations, but I'm not sure that means it's deserving of being correct, but only a very limited relative truth. As they look for explanations of gravitation better than General Relativity, I wonder what it'll look like in a thousand years from now?

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#### 27Thousand

"Many tell me". Who?

And no, apparently you do not understand.
Sources that it's more than just semantics, but rather an overturning for a scientific explanation for what gravitation really is (remember a law of gravitation - observable principle/implications - is not the same as the theory of gravitation - explanation):

"The general theory overturned Newton's theory of gravity which had been valid for two hundred and fifty years. In Newton's universe, gravity was regarded as an attractive force which all massive bodies exert on each other. The planets moved in elliptical orbits about the sun because of its great mass powerful gravitational force. In Einstein's universe, gravity is not regarded as an exterior force, but rather as a property of space and time or "spacetime"."
http://www.alberteinstein.info/gallery/gtext3.html [Broken]
If Einstein was so famous with curvatures in spacetime, then why was it only semantics? It has implications for making physical predictions, and if it's real (instead of other theories) then the possibility of an actual reality out there different than Newton's external force theory.

Something I found from the National Academy of Sciences, the highest Science organization in the U.S. http://books.nap.edu/openbook.php?record_id=751&page=8

Who is this "they" to whom you keep referring? Stop being a passive aggressive post-modernist. Say what you mean. When you are attributing something to someone, give a proper reference. Give a link. Otherwise I'll have to assume you made it up.

As far as gravitation being unobservable goes, you have to be careful as to what this means. We certainly can observe the effects of gravitation. It's really quite simple. Let an apple fall on your head. If the apple doesn't work, try something with more mass.

What we can't do is construct a device that measures gravitational force without looking at the outside world. Newtonian physics explains this in terms of the non-existence of a gravity shield. General relativity explains this in terms of curved space-time being a manifold. How the future physics that finally bridges the gap between general relativity and quantum mechanics will explain this, we don't know. That wedding has not yet taken place.
I'll get the source on that one from the National Academy of Sciences. Basically they're defending the theory (explanation) of evolution. They say some people accuse evolution over millions of years of not being directly observable because no one has a time machine. Then they say that happens all the time in Science; it's the same way for gravitation and x-rays. We can only observe the effects of them but not the actual thing itself, but that doesn't mean it's not reasonable. They say you can't prove in Science and it's always possible to change with new evidence, but that a scientific fact (besides also meaning an observation) is an explanation that's been tested so well that there's no longer any reason to doubt.

Looking at it, since there are so many theories or explanations of gravitation out there right now, how can we say we have actually observed gravitation itself (beyond the indirect effects or implications)? We have equations and observations, but gravitation itself is an unobservable that could be completely replace again in the future. That's what I meant earlier by a scientific theory being completely replaced but the implications staying almost the same. I said that was a realist argument for why we should trust Science as being approximately true.

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#### 27Thousand

27Thousand said:
As many may recall, physicsforums earlier said that you have to be so original that you can't even eat breakfast because "breakfast" is found in a dictionary.
Who is "physicsforums"? Where do you get this nonsense? I think you are making it up.

First of all, I took three words from a television show and added six new words to create a new phrase. It was something I didn't read and I thought of it on my own. So later I told my roommate the phrase. He laughed and said, "Not from a book!" Me, "I didn't get it from a book." Him, "Not from a book!" Then later in the day he laughed at me, said he was going to be creative, and quoted an extremely common movie quote. I went to Google and searched for his movie quote in quotes, hundreds of thousands of results came up. Then I Googled my made up phrase in quotes and apparently the only results which came up are when I've used it online. I thought that was hypocritical. Also, just like the atomic bomb flattened those Japanese cities it was like he was telling me to turn my mind into oblivion or a vegetable because all vocabulary words are automatically in one of the random millions of books in the world.

So I went to physicsforums.com and they said that maybe I needed to not be from a book and come up with my own ideas. I kept on saying that it was my own words. Then one person said since three words "the world around" was from a television show, that basically means it's from a book. That didn't make any sense to me because of what Google said.

I decided to ask another website about physicsforums.com and this is what they said, without me saying that it was actually physicsforums.com to protect the innocent :
I mean I could be wrong but if you have the mindset that you can't eat breakfast because "breakfast" is in a dictionary, I would believe that's irrational. I mean we have to be reasonable here.

#### 27Thousand

So that's why I said, "If we want to be as creative as the amount of rain drops falling in a rainstorm, and as imaginative as the rainbow afterward, the scientists who claim Science can change with new evidence will probably be the ones making the innovations."

#### emyt

all ideas come from the human mind, our standard of "truth" is just how an idea is relevant to our actual universe

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