Question about gravity

[Southwind17]

Haven't studies shown that the less someone knows about something they are often more confident in their knowledge of it?

Yes. Definitely.
OK, I have no idea.

Definitely? Oh, come now; a theory only, surely!

 

[edd]

'One could claim Calculus is wrong, if you apply the same level of perfection to the results of using it.'
What? Calculus is a branch of mathematics. It is true given the axioms from which it derives. Newtonian gravity is a physical theory, and one that's been superceded. I don't see how you can make that comparison.

 

[DrBaltar]

Have you ever heard of the "inverse square law"? It isn't considered "the inverse square theory", and if you were to talk about it like that, you would be considered uneducated.

Same for many other laws. Here is a list
http://en.wikipedia.org/wiki/Scientific_laws_named_after_people

Some laws are true by definition. Like 'A = A'. This is not a theory, it is the law of identity and is only a bullet proof Law because of the definition of '='. The inverse square law also must be true because it is a logical consequence of the math. There are many other laws in math that are true by definition.

Other laws were prematurely labeled a law when they were actually a theory. Such as "Newton's Law of Gravitation", which is listed in the 'Scientific laws named after people" link you posted. Newton's Law of Gravitation was prematurely labeled a law and later replaced by Einstein's Theory of General Relativity. If it were an actual Law, it could never be replaced. As the scientific method has become a standard in science, the word theory is used now rather than law.

 

[Cold one]

Robi you seem to just beg to mock someone while you don't have a clue about what is being talked about. I feel bad for you I really do.
Adherence to a "law" is saying that if new evidence comes up you will not re-assess your current "laws" and therefore better understand.
No one is attempting to "violate" any laws, merely saying that the world doesn't revolve around the sun because of gravity, only that gravity attempts to show how. IF new information becomes available the "law" should and will change to attempt to incorporate said info.

 

[ponderingturtle]

Good points. I think the problem here is that most people chiming in (who are wrong) don't have an engineering or physics background. Newton's inventing Calculus was a direct result of his experiments with gravity. One could claim Calculus is wrong, if you apply the same level of perfection to the results of using it. But nobody is going to stop using Calculus, or listen to you.

Calculus is math, and math can not be disproven, only shown to have a mistake in it. That means nothing about if it describes a specific thing accurately in the physical world.

 

[robinson]

No, it's an (approximate) description of nature, because it's a theory, and because it agrees with experiments, as long as you don't measure things with too much precision. (All theories are "made up" by the way).

Now we are back to a fundamental difference. As I pointed out, using Google searches (I doubt anybody looked at them, but oh well), statements like "Newton was wrong" or "Newton's Law of Gravity is wrong" only appear on Creationist websites.

Laws are called Laws because they work, not only to predict but to design and modify reality. If they don't, they are not considered laws of physics.
Some LOPs only are valid for certain spacetime situations, or are ideal laws, but that doesn't mean they are not LOPs. It means you have to know a lot more than an Internet forum can explain to know why they are still used, everyday, all the time. And people who claim they don't work are viewed with suspicion.

Like any good theory, it provides an approximate description or reality, or equivalently, an exact description of a fictional universe that's a useful model of our own.

We may be saying the same thing here. But nobody I know, in the real world, would say the LOPs are not laws. That would be creationism talk.

You keep showing that you're willing to hold on to your delusions like a creationist on crack.

What is so damn funny, is you are making that claim about famous and well respected scientific principles, backed up by hundreds of years of science and research. I'm not making anything up, I just steal from physics texts and respected scientist.

So every time somebody is claiming I am wrong, I just laugh about it.

Just like I laugh at stuff like this:

Almost all high school physics students are required to learn Newton's three "laws" of gravitation. These "laws" are presented as Absolute Truth, and many former students can still recite them from memory. However, we have known since the beginning of the 20th Century that these "laws" are nothing of the kind; Einstein's theory of general relativity is not at all compatible with Newton's "laws", and relativity has been experimentally demonstrated to be correct on numerous occasions. Newton's "laws" break down at large-scale levels (for instance, Newtonian mechanics cannot be used to accurately describe the orbit of the planet Mercury.) Relativity, on the other hand, is consistent and measurably correct on virtually all levels, with the possible exception of situations involving extreme mass and energy where quantum effects can no longer be ignored.

Newton's defenders say "well, okay .. perhaps Newtonian mechanics is not universally correct, but it works very well for situations here on Earth, and in that context it is very accurate." That is all well and good, but the fact remains that Newton was wrong, but physics instructors teach his "laws" anyway. And they are 100% justified in doing so. There is no way in hell that we should expect high school students to be able to understand the ramifications of general relativity. It's weird, wacky, and difficult stuff. Why can't we do the same thing with creationism? Why should we expect these impressionable children to be able to deal with the cold reality that is biological evolution?

http://www.adequacy.org/stories/2002.1.17.225621.189.html

So when I see some ignorant internet spew, about Newton being wrong, I think closet creationist. No credible scientist would say Newton was wrong about gravity. That is absurd.

 

[robinson]

What about GPS?.

Great question.

For GPS satellites, General Relativity predicts that the atomic clocks at GPS orbital altitudes will tick faster by about 45,900 ns/day because they are in a weaker gravitational field than atomic clocks on Earth's surface. Special Relativity (SR) predicts that atomic clocks moving at GPS orbital speeds will tick slower by about 7,200 ns/day than stationary ground clocks.

So we have to account for both factors.

Newton's theory is just an approximation to GR, although a very good approximation many times.

This cuts to the black heart of the matter. For calculating the force of moving objects or potential energy or stationary objects, on the planet itself, Newton's Law is correct. It is also correct in regards to Kepler's Laws of planetary motion, both of which match Einsteins equations.

The hundreds of years of observation since Kepler and Newton published their theories supports both of them. They are not wrong.

But they are also not valid for some situations. The same is true for GR, SR, and that is exactly why there are two theories used. See the above example about GPS.

 

[sol invictus]

If you believe that there are absolute, immutable laws of nature that will never be shown to be incorrect or inexact, you are acting on irrational faith and are no better than a creationist. Science could never demonstrate such a thing, and such a belief is the absolute antithesis of the scientific mode of thinking.

The history of science is of a series of theories, each more general and more accurate than the last. To say that Newtonian gravity is wrong without qualification is technically correct, but not very informative. It is almost right in most of the situations we are interested in. However it is completely wrong in some of those situations (for example gravitational lensing, or about the centers of galaxies), and a little bit wrong in all of them (and sometimes that little bit matters even on or close to earth, such as for the GPS system).

 

[edd]

For calculating the force of moving objects or potential energy or stationary objects, on the planet itself, Newton's Law is correct. It is also correct in regards to Kepler's Laws of planetary motion, both of which match Einsteins equations.

OK, correct is not the same as close enough for all practical purposes.

 

[ponderingturtle]

Laws are called Laws because they work, not only to predict but to design and modify reality. If they don't, they are not considered laws of physics.

Wrong. The only reason Newtons theories are called laws is that of tradition, they are not actualy laws. The best example of a law is likely concervation laws. These are stated assumptions that are the basis of theories.

 

[ponderingturtle]

Great question.

For GPS satellites, General Relativity predicts that the atomic clocks at GPS orbital altitudes will tick faster by about 45,900 ns/day because they are in a weaker gravitational field than atomic clocks on Earth's surface. Special Relativity (SR) predicts that atomic clocks moving at GPS orbital speeds will tick slower by about 7,200 ns/day than stationary ground clocks.

So we have to account for both factors.

Someone call the police they are violating Newtons Laws.

 

[robinson]

I always find it amusing when people with no clue what they are talking about try to argue with professionals.

Newton's Law of Gravitation was prematurely labeled a law and later replaced by Einstein's Theory of General Relativity.

Really? See, I've never heard anyone say that before. So, being a skeptic, I look to see if that can possibly be true. Because it sounds crazy.
http://www.google.com/search?hl=en&...prematurely+labeled+a+law"&btnG=Google+Search

See? You are the only person on the Google search engine to ever make that claim. So should I believe it? No.

If you, or anybody else can back up these crazy claims, please let us know what credible source you are getting this information from. Because this is fascinating stuff. Never I've never heard such claims about really important stuff. I would love to read the science behind it.

Everything I've said will show up in a search engine, because I stole it from one. It is all scientific stuff, not made up stuff.

 

[robinson]

OK, correct is not the same as close enough for all practical purposes.

To illustrate an example of what we are running into here, we could use a practical situation.

Newton, an amazing person really, calculated how much force a falling body, on the surface of the earth, had. He also calculated how fast it would be going based on how long it fell. He wanted to know exactly how fast it would be falling at any moment. This led to his inventing Calculus. He didn't even tell anybody about it for 25 years.

But he knew, and he alone, for 25 years, the way to calculate the force and acceleration of a falling object on our planet, at any moment in time. He applied the same calculations to the moon, and discovered something nobody else knew. His formulas, which describe reality, on our planet, are called laws, because they describe reality. They are not theories, they are a practical way to calculate and know information about falling bodies, and bodies at rest, in our gravitational field.

The inverse square law applies to the force of gravity, in regards to the observation of it on our planet. It isn't possible for it to be wrong, it is just a description of how things work. In the reference frame of our planet, nobody, except some creationist, would say Newton's Law of Gravitation is/was wrong.

It is heresy. Madness! Crazy talk!

 

[Yllanes]

Great question.

For GPS satellites, General Relativity predicts that the atomic clocks at GPS orbital altitudes will tick faster by about 45,900 ns/day because they are in a weaker gravitational field than atomic clocks on Earth's surface. Special Relativity (SR) predicts that atomic clocks moving at GPS orbital speeds will tick slower by about 7,200 ns/day than stationary ground clocks.

So we have to account for both factors.

SR is included in GR. You mean that there would be an effect of 7200 ns/day even without gravitation and that gravitation adds 45 900 ns/day. But GR includes both the gravitational effect and the effect due to the orbital speed.

But they are also not valid for some situations. The same is true for GR, SR, and that is exactly why there are two theories used. See the above example about GPS.

As I said before, GR is enough and correct so far as we know. Newton's laws are an approximation, much like GR may someday be shown to be an approximation of some more perfect theory. And of course that does not mean GR will then be useless, just like Newton's laws are not useless now. But it would be wrong in the sense that it would only be a simplification of a more complete theory.

There's no arguing this and I am not at all interested in a pointless semantic argument about what does 'wrong' mean, so I'm done with this subthread.

And the comparison with that creationist page was insulting.

 

[Irony]

Are you for real? See above.

You might be willing to admit that you understand nothing (which, frankly, seems plausible, given your views!). I, however, am not, because I do.

Have you forgotten the beginning of this discussion already? This is your standard we're talking about. If you find it to be completely ridiculous, then I've made my case.

 

[robinson]

Now in regards to the topic question, Gravity, the difference between on our planet and "out in space", that is a very good subject.

Based on all the popular theories, what we observe in far distant space does not match the theories. The motions of observed objects does not add up. According to theory (and here is where descriptions of Gravity is theory), it doesn't work. It isn't even close. In fact, it is so far off, scientist working with Gravity theories had to invent dark matter and dark energy to make the theory match observed reality.

They have to add 10 times more invisible, undetectable, mythical dark matter to the equations, or they don't work. Matter that does not act like matter, does not reflect, absorb, refract or interact with either matter or energy, as we know it. In order for the theories to be "right", (which we know work, based on near earth observation and science and stuff), they created a theoretical substance.

If you tell them it is just a theory, (as some here have pointed out), they get annoyed. Are theories made up? Are they true? Are the physical laws about gravity true everywhere? Good stuff. Does anybody really know?

Gravity is currently one of the biggest mysteries of modern science. Not local gravity, we understand that very very well, and use our understanding to send probes, satellites and human being into orbits all the time, and we are exact about it. There is no dark matter of dark energy needed to calculate local gravity, The planets around the sun, and the moons around the planets, and falling bodies on earth, they are all calculated with precision, no dark matter needed or required.

But waaaay out in space, you have to add a huge amount of invisible mystical stuff to the equations to make them work. Fascinating situation really. At least to me, cause I just don't that much about it I guess.

 

[Irony]

It is heresy. Madness! Crazy talk!

Science is not a religion, Newton was not a prophet, there is no such thing as heresy in science, and if you think that Relativity is crazy talk then FSM help you if you ever delve into quantum theory.

 

[sol invictus]

Really? See, I've never heard anyone say that before. So, being a skeptic, I look to see if that can possibly be true. Because it sounds crazy.
http://www.google.com/search?hl=en&...prematurely+labeled+a+law"&btnG=Google+Search

See? You are the only person on the Google search engine to ever make that claim. So should I believe it? No.

Are you serious??? I'm half inclined to think you're just putting us all on... do you really consider this a good argument?

I think eggs are good to eat for breakfast. Let's search for that on google:

http://www.google.com/search?hl=en&safe=off&q="eggs+are+good+to+eat+for+breakfast"&btnG=Search

OH MY GOD!!! NO ONE HAS EVER SAID THAT BEFORE!! IT MUST BE WRONG!!!

If you, or anybody else can back up these crazy claims, please let us know what credible source you are getting this information from. Because this is fascinating stuff. Never I've never heard such claims about really important stuff. I would love to read the science behind it.

Did you read the quote from Einstein above? Is he credible, according to you? Have you heard of him?

 

[edd]

Based on all the popular theories, what we observe in far distant space does not match the theories. The motions of observed objects does not add up. According to theory (and here is where descriptions of Gravity is theory), it doesn't work. It isn't even close. In fact, it is so far off, scientist working with Gravity theories had to invent dark matter and dark energy to make the theory match observed reality.

They have to add 10 times more invisible, undetectable, mythical dark matter to the equations, or they don't work. Matter that does not act like matter, does not reflect, absorb, refract or interact with either matter or energy, as we know it. In order for the theories to be "right", (which we know work, based on near earth observation and science and stuff), they created a theoretical substance.

We've not created anything. We've discovered a number of phenomena which are best explained currently by proposing dark matter and dark energy. We have detected in laboratories hot dark matter (but not cold, which is what is needed to explain the observations in question) - namely the neutrino.

With dark energy we've not even satisfied ourselves as to whether there is a dark energy component or if gravity is in some way modified. (and the same applies to some extent with dark matter and MOND-like theories, although the case for that seems somewhat weaker than in the past)

What has happened is that the minimum alterations to the models have been made to explain the current observations. The issue of the dark sector components to the universe is far from resolved, but most of us in the field would suggest the 'standard' dark energy and dark matter components are currently looking most likely.

Oh and when you say this:

Matter that does not act like matter, does not reflect, absorb, refract or interact with either matter or energy, as we know it.

a) it acts like matter, just collisionless matter
b) it does of course interact with baryonic matter and other more 'everyday' forms of energy - gravitationally
c) some models of dark matter suggest that it does very weakly interact with matter in other ways
d) again a reminder that neutrinos been detected, having originally been posited as weakly interacting particles necessary to explain anomalous observations, suggesting cold dark matter is not really a tremendous revolution, it merely involves positing another variety of particle ('merely' being something of a relative term)

 

[robinson]

Are you serious??? I'm half inclined to think you're just putting us all on...

Did I mention I was going to mock you?


































Oh yes, I did.