Warping of space and special relativity?

[zonde]

I now think what you're saying is that people come up with a personal philosophy, (i.e. "crap filter" means personal philosophy), and if the personal philosphy that they come up with is incompatible with relativity, they reject relativity, rather than think about whether or not their personal philosophy has problems.

With "crap filter" I was meaning some quality control. Imagine that the person is asking you: "Why should I trust you?", and you are saying: "Ok, close your eyes and I will tell you why." This probably won't work because this is suspicious and not very clear why it is needed.

Likewise about relativity if you want to redefine important concepts before you have proved that you can be trusted (your viewpoint is realistic) it rises suspicions. So if you want to make a point, make it without redefining space and time. If you need some coordinate dependent quantities similar to pre-relativistic space and time call them differently, for example, "clock rate" and "ruler length".

 

[Dale]

I understand about parameters. I do not understand why test theory is required (and maybe what it is). If you want to make your point maybe you can give example? What would be test theory in case of Shapiro delay experiment?

For Shapiro delay the test theory would be PPN which I mentioned above. In the PPN formalism the Shapiro delay is proportional to the PPN parameter γ, meaning that a measurement of the Shapiro delay gives a measurement of the PPN parameter γ:
http://en.wikipedia.org/wiki/Shapiro_delay#Time_delay_due_to_light_traveling_around_a_single_mass

If that value is 0 (to within experimental error) then the test supports Newtonian gravity, if the value is 1 (to within experimental error) then the test supports GR.Currently, the experimental data places γ at 1±2.3x10^-5. This confirms GR and falsifies Newtonian gravity:
http://www.nature.com/nature/journal/v425/n6956/full/nature01997.html

With "crap filter" I was meaning some quality control.

The ultimate crap filter in science is experimental evidence. That is how you prove that your viewpoint is realistic and that your redefinitions are worthwhile.

 

[Fredrik]

Likewise about relativity if you want to redefine important concepts before you have proved that you can be trusted (your viewpoint is realistic) it rises suspicions. So if you want to make a point, make it without redefining space and time.

But a person who gets suspicious about that hasn't understood what science is. So it would make a lot more sense to explain that first and then make the necessary definitions, than to pretend that his views are valid.

 

[zonde]

For Shapiro delay the test theory would be PPN which I mentioned above. In the PPN formalism the Shapiro delay is proportional to the PPN parameter γ, meaning that a measurement of the Shapiro delay gives a measurement of the PPN parameter γ:
http://en.wikipedia.org/wiki/Shapiro_delay#Time_delay_due_to_light_traveling_around_a_single_mass

According to wikipedia Shapiro delay is proportional to (1+γ) not γ. But certainly it is enough to have $\Delta t$ to test GR.

If that value is 0 (to within experimental error) then the test supports Newtonian gravity, if the value is 1 (to within experimental error) then the test supports GR.Currently, the experimental data places γ at 1±2.3x10^-5. This confirms GR and falsifies Newtonian gravity:
http://www.nature.com/nature/journal/v425/n6956/full/nature01997.html

Interesting experiment.

The ultimate crap filter in science is experimental evidence. That is how you prove that your viewpoint is realistic and that your redefinitions are worthwhile.

Experiment can not prove that your viewpoint is realistic. Haven't you heard about particle wave duality or quantum entanglement? And how can experiment prove that we have to use particular word in our definition?

I agree that experiment is the ultimate crap filter in science. But unfortunately it can not prove anything, only disprove something.

 

[zonde]

But a person who gets suspicious about that hasn't understood what science is. So it would make a lot more sense to explain that first and then make the necessary definitions, than to pretend that his views are valid.

Take math. If we have one variable at two different places and I am not sure it's the same it should be OK to use two different variable names and check that they come together somewhere along derivation as clearly the same variable. There is nothing unscientific about that. The same with definitions. Where is the problem in giving different name for your defined concept and checking that at the end it looks the same as the old one?

 

[Fredrik]

Take math. If we have one variable at two different places and I am not sure it's the same it should be OK to use two different variable names and check that they come together somewhere along derivation as clearly the same variable. There is nothing unscientific about that. The same with definitions. Where is the problem in giving different name for your defined concept and checking that at the end it looks the same as the old one?

If you would prefer to invent a new and non-suggestive term like "flurpiness" for $(\gamma-1)m$ instead of calling it "kinetic energy" when you're trying to explain SR to someone, then I don't have a problem with it. I would however prefer to just explain that it's very common that two theories assign different meanings to the same term.

 

[Dale]

According to wikipedia Shapiro delay is proportional to (1+γ) not γ. But certainly it is enough to have $\Delta t$ to test GR.

Oops, you are correct. Thanks.

Experiment can not prove that your viewpoint is realistic.

Sure it does. How else would you prove that it is realistic?

Haven't you heard about particle wave duality or quantum entanglement?

Yes, the related experiments clearly demonstrate that reality is weird.

 

[pervect]

With "crap filter" I was meaning some quality control. Imagine that the person is asking you: "Why should I trust you?", and you are saying: "Ok, close your eyes and I will tell you why." This probably won't work because this is suspicious and not very clear why it is needed.

Likewise about relativity if you want to redefine important concepts before you have proved that you can be trusted (your viewpoint is realistic) it rises suspicions. So if you want to make a point, make it without redefining space and time. If you need some coordinate dependent quantities similar to pre-relativistic space and time call them differently, for example, "clock rate" and "ruler length".

I guess my general comment is that if someone's personal "crap filter" is falsely filtering out relativity, their "crap filter" needs a little bit of adjustment. A little bit like someone's mailbox filter putting important messages in the spam container.

Since the only coordinate independent quantity in relativity is the Loretnz interval, any breaking up of the Lorentz interval into a "time difference' and a "space difference" is going to be coordinate dependent. So it's not that we need coordinate dependent quantities for time and distance, it's we can't avoid getting rid of the concept of "universal time", a time that's coordinate independent, because it no longer exists.

A plea to "explain relativity in terms of some "universal time" just like you used to believe in is just not going to work. Sorry.

As far as any obligation to "prove realism", I can't really agree. It appears to me to be the all-too-common case of some personal philosophy (here said philosohpy is being called realism, and may or may not be related to what a philosopher would call realism) is inhibiting the understanding of relativity. It's sad, but I don't think there's much that can be done about it.

 

[Dale]

As far as any obligation to "prove realism", I can't really agree. It appears to me to be the all-too-common case of some personal philosophy (here said philosohpy is being called realism, and may or may not be related to what a philosopher would call realism) is inhibiting the understanding of relativity. It's sad, but I don't think there's much that can be done about it.

Well said. That is why experiment is the final arbiter of realism.

 

[pervect]

One other comment I have to make. That is the tricky matter - it's possible with enough detachment to work with a theory, to understand it, without totally believing it as an absolute, to think of it as "if this is true, then the rest follows".

It's sort of a hard way to proceed, to believe something enough to see where it leads while keeping one's mind open about the truth of the precondtions.

It's certainly preferrable way to look at relativity this way. In fact that's probably the scientific ideal - to always keep in mind that the premises might be wrong. Just rejecting it out of hand because it doesn't match one's preconceptions really isn't right, though it seems there is a sort of counter-culture that encourages it (why, I don't know). If some of the preconceptions are very strong, it can be hard to overcome them :-(.

 

[zonde]

One other comment I have to make. That is the tricky matter - it's possible with enough detachment to work with a theory, to understand it, without totally believing it as an absolute, to think of it as "if this is true, then the rest follows".

It's sort of a hard way to proceed, to believe something enough to see where it leads while keeping one's mind open about the truth of the precondtions.

It's certainly preferrable way to look at relativity this way. In fact that's probably the scientific ideal - to always keep in mind that the premises might be wrong. Just rejecting it out of hand because it doesn't match one's preconceptions really isn't right, though it seems there is a sort of counter-culture that encourages it (why, I don't know). If some of the preconceptions are very strong, it can be hard to overcome them :-(.

I would like to continue discussion from here. You have formulated it much better and more up to the point.

So if the person you are trying to teach about relativity is going the hard way it might be that at some point he can't maintain that detachment and he has to stop to sort things out. It does not mean that he is rejecting relativity, he just can't go at the pace you are pushing him.

But you can go faster (I guess) if you can present your point already in that detached form so that the person has to do less "translation".