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Come on, REAL Physics please!


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#35 Roadam

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Posted 17 October 2008 - 01:18 PM

Alright, but as I see it, the theory of relativity just states the transformations between systems. So if a rocket accelerating close to speed of light, and one of its thrusters would give it a transversal push, observer in the other inertial system would see the behavior of this force according to transformation rules.

There still is nothing that would suggest that spacecraft accelerating perpendicular to its velocity would get accelerated transversal to it.

Edit: After getting another look. Now I I see what it really is that you gave me in that link.

Posted Image

That just means that if you want to accelerate transversally you need a lot less energy for the same effect.

#36 Pyrotex

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Posted 17 October 2008 - 01:37 PM

But Relativity predicts a transverse force, then, how do you explain?

Well, while working on my Masters Degree in Physics at Mississippi State University, I took classes in Intermediate and Advanced Relativity. They were tough.

As far as I can remember, Relativity NEVER predicts a transverse force just appearing out of nowhere. Or as a result of purely longitudinal accelleration.
F=ma (in the Newtonian form) is a Vector equation; F and a are the vectors and they are always colinear. Even in Relativity.

The ONLY way I can think of that Relativity or Newton would "predict" a transverse force from a longitudinal accelleration is in a rotating frame of reference.

I couldn't read the article because I couldn't find it to be available freely in your link.

;) :) :D
The link "works". I can read out of Poincare's book. However, you may not be able to read ALL pages. That shouldn't be a problem. ALL pages aren't under consideration here. Just the reference to "transverse mass" which turns out to be his way of saying "inertia against a transverse force".

[EDIT] Roadam's last post nails it. Okay. That's why you think Relativity predicts a transverse force. You're translating between frames of reference!! :D :D :) Everything clears up now.

Thanks Roady!!!!!!!!!!!

#37 martillo

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Posted 17 October 2008 - 02:04 PM

Anyway, may be even if present any relativistic effect could be neglihible since the velocity of the rockets are very small when compared with light velocity, isn't it?

The main point I adress is that the real equation of force is F=ma and not F=dp/dt as currently stated (Pyrotex seems to not know that currently even in Newtonian Physics is considered F=dp/dt and not F=ma when mass varies, just take a modern Physics book or see at wikipedia).

The complete reasoning analizing rockets' motion is presented at Appendix A :The real Equation of Force is F=ma.

You can see there how actually in any rocket's motion the relation F=ma is currently being used and not F=dp/dt.

This is an evidence against Relativity Theory since this theory is based in the relation F=dp/dt. For example the equation E=mc2 is derived form that relation. (just google for "relativistic energy derivation").
A right theory cannot be based on a wrong relation for force.

#38 Roadam

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Posted 17 October 2008 - 03:10 PM

The reason for using momentum instead of mass is because you cant really define mass without force and force without mass.

But both are actually one an only.
F=m*a
using a=dv/dt
F=m*dv/dt
then p=m*v so dp=m*dv or dp=dm*v
F=dp/dt

Need anything else?

#39 Roadam

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Posted 17 October 2008 - 03:22 PM

Ok, that last post was screwed.

Actually what you are doing wrong on your site is using rocket equation.

F = m(dv/dt) = -u(dm/dt)


That dm/dt is actually mass flow out of the rocket at the speed of u relative to the rocket. So dm is not the change of the mass by traveling near the speed of light. :hyper:

And where did you get that definition? :

By definition p = mv and dp/dt = m(dv/dt) + v(dm/dt).



#40 martillo

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Posted 18 October 2008 - 04:22 AM

Hey, haven't you ever heard about "partial derivatives", the derivation of a function with more than one variable in mathematics?
d(f(x,y))/dt= d(f(x,y))/dx.dx/dt + d(f(x,y))dy.dy/dt
which in abreviated form takes the form df/dt= df/dx.dx/dt + df/dy.dy/dt

By definition p=mv where in principle both m and v can vary as in the case of rockets which have variable mass due to the expelled fuel.
Then:
dp/dt= m.dv/dt + v.dm/dt

This means that dp/dt=mdv/dt=ma just when mass does not vary (constant mass) which is not the case of rockets!

Actually what you are doing wrong on your site is using rocket equation.

Quote:
F = m(dv/dt) = -u(dm/dt)

Google or Yahoo for "rocket motion" or "rocket motion equation" and see what you obtain.
In my "Appendix A" there are two links I consider relatively well explained but make your own search if you want.

#41 Roadam

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Posted 18 October 2008 - 05:02 AM

That derivation is useful for when the mass of an object in observation really varies. But the mass of whole system, fuel and the rocket doesn't change.

Theory of relativity doesn't predict any simple changes of mass. You would of course state that longitudinal mass is increasing, but hey, that is in the equation: F=y^3*m*a . Which only tells us that we should in out observation put a factor into the equation. That factor increases to infinity when we are approaching the speed of light.

That imaginary increase of mass is just another paradox like result of the special relativity, just like time dilation, and shortening of the distances...

The only place when mass is really changing is in particle physics. But even there special relativity explains everything we saw up to now with utmost precision.

#42 martillo

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Posted 18 October 2008 - 12:37 PM

I think you didn't get to the point.
Sometimes is really hard to explain...


Again: How slow is this site!
I tried in different computers and in different places and the same, any page lates a lot to appear in the screen. This does not happen with any other forum I have visited (many).
It must be something with the software of the forum's site. This should be reviewed.

#43 Roadam

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Posted 18 October 2008 - 01:27 PM

I am just saying that the second part of partial derivative isn't used because mass doesn't just change.


PS: maybe these other forums are located in Uruguay. Who knows how strong net connections you have there.

#44 Pyrotex

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Posted 18 October 2008 - 02:16 PM

...By definition p=mv where in principle both m and v can vary as in the case of rockets which have variable mass due to the expelled fuel.
Then:
dp/dt= m.dv/dt + v.dm/dt

This means that dp/dt=mdv/dt=ma just when mass does not vary (constant mass)...

Just thought I would throw in an "Amen and Huzzah" for Martillo on this post. This is from the "rocket equation", a simple generalization of Newton's F=ma. All of NASA rocket designs are based on this.

F = dp/dt
and
F = ma
are BOTH correct. And when dm/dt = 0 (constant mass), BOTH equations are identical and equivalent.

#45 Pyrotex

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Posted 18 October 2008 - 02:23 PM

I am just saying that the second part of partial derivative isn't used because mass doesn't just change...

Roadam,
if you mean that the inherent mass of the atoms in the rocket doesn't change, then you would be (sort of) correct.
But the second part of the partial derivative IS USED and is absolutely critical in designing rockets.

The force generated by the rocket engines PUSH against the rocket and accelerate it upwards.

The force, F, is the force applied to the rocket from the engines.
The accelleration, a, is the accelleration of the rocket.
The mass, M, is the mass of the rocket.

The mass of the rocket is changing when fuel is being burned.
The engines are NOT pushing against the burnt fuel that is expelled, only against the fuel that is still inside the rocket. So dm/dt < 0 , that is, the change is negative, because it is a LOSS of mass. (as long as the engines are burning).

#46 Roadam

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Posted 18 October 2008 - 03:01 PM

Well I know it is used in calculating motion of rockets. I know how to use them and why it is like it is.

I am just saying that martillo is using the same equations to show that special relativity is wrong.

His first post:

Forces cannot be unified at all.
This is just another silly paradigm setted by an Einstein's thought, the same as "particles' entaglement". Just silly and wrong statements.
And there are many physicists braking their minds, wasting time and money in such "paradigms"...

Not to say Relativity Theory is really a wrong theory.
But not only Einstein was wrong, also De Broglie's waves actually do not exist.(Actually there are no "waves associated to matter", only a wave-like behavior!).

To continue wasting brain, time and money?
Note also that from wrong theories only wrong predictions can surge...

Wake up! Open the eyes! There's an entire totally new big possibility in Physics!

Time to rethink it all!

Don't miss...


martillo:
No matter how crazy the theory is or who makes it. Its only confirming those predictions that matters.
Entanglement has been predicted and experimentally confirmed, as well as De Broglie's waves were.
As for unifying the forces... Its just that every physicist wants to explain what is happening in the nature. So we are making theories, doing experiments, and if experiments don't agree with a theory, we make a new theory.

Its that we all want to understand everything.

And we are awake with our eyes wide open and thinking till our heads hurt. :D
And when there weren't new big possibilities in physics?

#47 martillo

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Posted 19 October 2008 - 02:59 AM

I think Pyrotex got it right.

Note that in the calculation of the rocket's motion equation first the principle of conservation of momentum is applied to the total system composed of the rocket plus the expelled fuel. This system has constant mass but the equation are expressed in terms of the variable mass of the rocket including its contained fuel which varies.
In the equations "m" accounts for that variable mass.

#48 Pyrotex

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Posted 20 October 2008 - 12:22 PM

...Note that in the calculation of the rocket's motion equation first the principle of conservation of momentum is applied to the total system composed of the rocket plus the expelled fuel. This system has constant mass but the equation are expressed in terms of the variable mass of the rocket including its contained fuel which varies.
In the equations "m" accounts for that variable mass.

Excellent. That is an accurate interpretation of my post. Thanks.

In a previous post, you mentioned that the increase of mass predicted by relativity was imaginary, except for particle physics. Well, no. I can't go into all of it now (I have a meeting in a few minutes) but I would like you to consider this fact:

Special Relativity is NOT about what happens to the rocket.
SR is about what the ground observer OBSERVES. SR predicts what the observations of the rocket will look like. The only thing that SR predicts about the rocket getting faster and faster as it jets away is just this--what will the folks in the initial frame of reference OBSERVE as they watch the rocket.

SR is not magic. It is based on dirt simple geometry. Light has a finite value. It is not infinitely fast. Think of photons like extremely fast pingpong balls bouncing of the rocket, bouncing toward the folks on the ground, who catch the balls in their "pingpong" telescope and deduce what is happening to the rocket.

When the rocket travels slow, this is easy and gives common sense values.

When the rocket travels near the speed of the pingpong balls, the geomety of collisions and angles begins to change drastically. What will be OBSERVED is the classical fore-shortening of length, the classical slowing of rocket-time, and the classical decrease of rocket-accelleration (which is rightfully intepreted as due to increase of rocket-mass).

The slowing of time has been measured by satellites with atomic clocks. The increase of mass has been measured with atomic particles--if it works for them, why should it not work for larger particles? Where do you draw the line? dust motes? mustard seeds? marbles? automobiles? rockets?

#49 martillo

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Posted 20 October 2008 - 02:06 PM

The slowing of time has been measured by satellites with atomic clocks. The increase of mass has been measured with atomic particles

The new theory gives a different interpretation for those experiments. It proposes that the results obtained actually happen due to a different physical phenomena.

In Section 1.1 is pointed:

D) Summary of new interpretations of relativistic experiments

Here is presented a summary of all the experiments which have here in this text an alternative interpretation to that of Relativity Theory:

1) Kaufmann experiment treated in Section 2.3.

2) The strong magnet experiment treated in Section 2.3.

3) Creation/annihilation processes related to the famous equation E=mc2 treated in Section 5.2.

4) Michelson-Morley experiment treated in Section 8.2.

5) Transversal Doppler Effect treated in Section 8.4.

6) Fizeau experiments treated in Section 8.5.

7) Davisson-Germer experiment treated in Chapter Six.

8) Mercury’s orbital precession treated in Appendix B - A.

9) The bending of light treated in Appendix B - B.

10) About “time dilation” phenomena treated in Appendix B - C.


In the new thepry even the famous equation E=mc2 is valid but with a new physical meaning.

The new theory agrees with all Physics' experiments already done but gives an amazing new interpretation to some of them.

The problem is not in the experiments but in the theories behind.

#50 Pyrotex

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Posted 20 October 2008 - 02:34 PM

The new theory gives a different interpretation for those experiments. ...The problem is not in the experiments but in the theories behind.

But martillo, what exactly IS the problem?

Einstein's theories predict exactly what we observe in the experiments.

There's no problem that needs solving.

And Relativity is simple. It has only one assumption that I know of: the speed of light is a constant in all inertial frames of reference. Beyond that, it is based on geometry. There have been NO experiments that produced conflicting observations. :shrug:

What exactly IS the problem?

#51 Roadam

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Posted 20 October 2008 - 03:01 PM

Mercury s precession, bending of light and gravitational lenses have all been calculated down to experimental error. Your theory should at least do better if at all.

As it is only possible to prove someone wrong, and not that he is correct. If he is we simply haven't found a way to prove him wrong.

For calculating light bending you proposed "trains of photons". How would that make the result better, and how would you calculate that.