# Common Misconceptions in Physics

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#### topsquark

Forum Staff
@oz: We don't invent terms just for the heck of it. If we are using the terms active and passive mass that means that there is a distinction between the two. See here.

Yes, Physics can get complicated. The extra nomenclature is there to make sure everyone is on the same page. Nothing more.

-Dan

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#### oz93666

@oz: We don't invent terms just for the heck of it. If we are using the terms active and passive mass that means that there is a distinction between the two. See here.

Yes, Physics can get complicated. The extra nomenclature is there to make sure everyone is on the same page. Nothing more.

-Dan
I've just looked at that link , topsquark .... there is just one sentence in the whole article dealing with this subject , ...here it is ...

" We might distinguish two kinds of gravitational mass, active and passive. The active gravitational mass is the source of the object's gravitational field, while the passive gravitational mass responds to it. ..."

LOL .... who comes up with this stuff????

Do I have to point out the flaw in that??? It's that never has an item exhibited "passive" mass without also exhibiting so called "active" mass also !!

It's a theoretical game , a hypothesis that cannot be proved by experiment , doesn't help our calculations or understanding in anyway way !!!

In another 15 years these terms too will fade into obscurity ...

Just because an idea is partially accepted by mainstream does not mean it's correct ... we must resist the instinct to blindly believe 'authority' ...

Question everything !!

#### topsquark

Forum Staff
I've just looked at that link , topsquark .... there is just one sentence in the whole article dealing with this subject , ...here it is ...

" We might distinguish two kinds of gravitational mass, active and passive. The active gravitational mass is the source of the object's gravitational field, while the passive gravitational mass responds to it. ..."

LOL .... who comes up with this stuff????

Do I have to point out the flaw in that??? It's that never has an item exhibited "passive" mass without also exhibiting so called "active" mass also !!

It's a theoretical game , a hypothesis that cannot be proved by experiment , doesn't help our calculations or understanding in anyway way !!!

In another 15 years these terms too will fade into obscurity ...

Just because an idea is partially accepted by mainstream does not mean it's correct ... we must resist the instinct to blindly believe 'authority' ...

Question everything !!
Um, wow.

"Who comes up with this stuff?" Professionals that know what they are talking about.

Newton's 2nd: $$\displaystyle \sum F = ma$$

Newton's Law of Gravity: $$\displaystyle F_G = \frac{Gm_1 m_2}{r^2}$$

There is nothing that says that the masses in these two equations should be the same. There is no practical difference as far as experimentation and calculations are concerned but no real theory that says why. And the controversy has been going on since Newton introduced these equations some 400 years ago. It's not going to go away in 15 years.

As it happens I do question authorities. Any professional scientist would say the same. (At least they had better. Experiments drive Physics.) And personally, anyone who says that I accept the mainstream without question clearly needs to read my master's thesis. And there have been any number of examples of Physicists that have fruitfully "bucked the system" in the past.

Look, if you want to think that the scientific community is there to make things more complicated then fine. I simply do not understand why you are trying to say otherwise. What is the point of doing this? No one is making money from this and no one is getting any fame from it. Given that, what purpose would it serve?

-Dan

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#### benit13

LOL .... who comes up with this stuff????
Further to TopSquark's post...

I found a paper where the authors describe a particular quantum mechanics experiment where the eigenstates of the problem depend on gravitational and inertial masses separately in different ways. Such an experiment could, therefore, be used to test further whether there are, indeed, any differences to gravitational and inertial mass.

https://arxiv.org/pdf/1006.1988.pdf

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#### oz93666

The two posts above have slipped back into discussing gravitational vs inertial mass ..

Which is completely different from active and passive gravitational mass

Although all four adjectives serve no purpose IMHO ...

...Look, if you want to think that the scientific community is there to make things more complicated then fine. I simply do not understand why you are trying to say otherwise. What is the point of doing this? No one is making money from this and no one is getting any fame from it. Given that, what purpose would it serve?

-Dan
This is a long (conspiratorial) story , best suited for another thread ... If I find the time I hope start it .

#### oz93666

Further to TopSquark's post...

I found a paper where the authors describe a particular quantum mechanics experiment where the eigenstates of the problem depend on gravitational and inertial masses separately in different ways. Such an experiment could, therefore, be used to test further whether there are, indeed, any differences to gravitational and inertial mass.

https://arxiv.org/pdf/1006.1988.pdf
Well that's great ... if they do the experiment and find there is a difference , then of course that would get the nobel prize and I would have no argument to using those two terms ...

But to date no one has detected a difference, so mass is mass is mass.

#### studiot

oz93666 post#5
But let me play devils advocate to get a debate going ....
Was your failure to engage in proper debate something to do with this devil and was this devil Tasmanian?

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#### Pmb

PHF Hall of Fame
Further to TopSquark's post...

I found a paper where the authors describe a particular quantum mechanics experiment where the eigenstates of the problem depend on gravitational and inertial masses separately in different ways. Such an experiment could, therefore, be used to test further whether there are, indeed, any differences to gravitational and inertial mass.

https://arxiv.org/pdf/1006.1988.pdf
I hope you're not trying to convince Oz of something? Its not possible.

As I said above active gravitational mass is defined through a tensor. Its not only possible but we know that active gravitational mass density can be negative. That's why the universe is expanding at an accelerating rate.

Are you familiar with a vacuum domain wall? The stresses inside the wall are negative which also yields a negative active gravitational mass. When a normal object having a positive passive gravitational mass is placed in the field its repelled by the wall.

Also as I indicated above, the active gravitational mass density of a body is different than the passive gravitational mass density. I already explained this but knew in advance that Oz wouldn't merely ignore it but probably laugh at it.

I get a nice warm fuzzy feeling when Oz makes all of my predictions about him come true.

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#### topsquark

Forum Staff
I hate to close the thread as it can help others if they need it but this is just getting out of hand. Let's change topics folks, to help out with other issues. I would prefer that y'all restart this conversation in a new thread.

-Dan

PS: I am going to close the thread after all and put a new one up under the same title.

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