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Old 17th September 2014, 01:33 AM   #81
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Originally Posted by Reality Check View Post
which is just wrong, WaterBreather.
Special relativity states that an object moving relative to an observer will be measured by that observer to have its length contracted in the direction of movement. That is not space contracting. Special relativity has no contracting or expanding space.
If I point my spaceship at Alpha Centauri and accelerate to relativistic speeds I'll observe the distance to AC decreasing, as the Sun-AC axis is now moving relative to me. Calling this "space contracting" isn't far off the mark.

Saying it refutes Einstein when combined with space inflating is of course naive nonsense.
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Old 17th September 2014, 05:34 AM   #82
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Reality is hard.
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Old 17th September 2014, 06:01 AM   #83
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Originally Posted by Belz... View Post
Reality is hard.
Whining is easy.
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Old 17th September 2014, 05:44 PM   #84
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Whining about reality is pointless.
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Old 17th September 2014, 06:01 PM   #85
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Originally Posted by Gord_in_Toronto View Post
Whining about reality is pointless.

But it's easy and there's no math.
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Old 18th September 2014, 03:09 AM   #86
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Originally Posted by Spindrift View Post
Whining is easy.


Dining requires more effort.
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Old 24th September 2014, 05:06 AM   #87
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As an open minded person, I'm still anxiously awaiting at least a little nibble of his theory.
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Old 6th October 2014, 10:59 AM   #88
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For the primitive minded, even seeing is "Believing", thus they can't even see the truth, thus once again they can be deceived. For instance, there are people out there in the world who think that a car can stop, start moving again, and then stop again, when in truth this is absolutely impossible.

However, for those who chose to be smarter than an eyeball, they can see that all objects in actual fact are constantly in motion and never stop being in motion. All objects are constantly in motion in one direction or another within the 4 dimensional environment known as Space-Time. This magnitude of this motion is the same as the speed of which light is moving across space.

A simple step by step analysis of this constant motion will lead you to fully understanding Special Relativity, and it will produce all of the SR equations thus covering Length Contraction, Time Dilation, the Transformation Equations, and the Velocity Addition equation. No education in physics is required to accomplish this. ( Watch videos 1 - 9 located at http://goo.gl/fz4R0I for proof of this analysis. 1 1/2 hour total. )

With just a little bit of intelligence, anyone can discover Special Relativity, but only if they learn to look in the direction of truths.
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Old 6th October 2014, 12:37 PM   #89
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Originally Posted by MINISTERofTRUTH View Post
For the primitive minded, even seeing is "Believing", thus they can't even see the truth, thus once again they can be deceived. For instance, there are people out there in the world who think that a car can stop, start moving again, and then stop again, when in truth this is absolutely impossible.

However, for those who chose to be smarter than an eyeball, they can see that all objects in actual fact are constantly in motion and never stop being in motion. All objects are constantly in motion in one direction or another within the 4 dimensional environment known as Space-Time. This magnitude of this motion is the same as the speed of which light is moving across space.

A simple step by step analysis of this constant motion will lead you to fully understanding Special Relativity, and it will produce all of the SR equations thus covering Length Contraction, Time Dilation, the Transformation Equations, and the Velocity Addition equation. No education in physics is required to accomplish this. ( Watch videos 1 - 9 located at http://goo.gl/fz4R0I for proof of this analysis. 1 1/2 hour total. )

With just a little bit of intelligence, anyone can discover Special Relativity, but only if they learn to look in the direction of truths.

Are these the same 9 videos you promoted in that other thread? The same videos that conflate velocity and position for the express purpose of supporting a nonsense result? Those videos?
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Old 6th October 2014, 01:24 PM   #90
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Originally Posted by bjornart View Post
If I point my spaceship at Alpha Centauri and accelerate to relativistic speeds I'll observe the distance to AC decreasing, as the Sun-AC axis is now moving relative to me. Calling this "space contracting" isn't far off the mark.
But if I remain at home watching you go to Alpha Centauri, I will not measure the distance to Alpha Centauri decreasing. Thus calling this "space contracting" is quite far off the mark. It is what it is called - length contraction .
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Old 6th October 2014, 01:36 PM   #91
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Originally Posted by MINISTERofTRUTH View Post
For the primitive minded, ..snipped lots of "primitive minded" text !....
As jsfisher points out - invalid science by YouTube video remains invalid.
These videos popped up in the "The paranormal science of relativity" thread on 6th January 2014 and were quickly seen to be wrong:
Originally Posted by jsfisher View Post
Well, sure...if you continually equivocate about your "space" axis being position or velocity and you wave your hands to introduce rotation and you mysteriously combine half of one expression with half of another expression with no justification...yeah, you can "derive" quite a lot.
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Old 13th October 2014, 11:18 AM   #92
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As for Einstein being a naysayer:

He put Newtonian physics on an even firmer footing than it had been before: in GM, slow things down to speeds much below c and you effectively get Newton.

He built on the work of Poincare, Noether and especially Maxwell. Maxwell's work threw out the value of c: the kinetic energy of a photon was shown to be 1/2 mc2. People asked "relative to what?". Maxwell assumed it was relative to the non-existent luminiferous ether. Michelson and Morley showed that to be false. Einstein just went further and said effectively, "OK, let's assume c is not a variable but a constant, and see where that leads."

Einstein didn't naysay, he was just prepared to follow assumptions through to their necessary conclusions and work out the consequences.

Einstein got where he did by yea-saying, not naysaying. He assumed Maxwell was right, and then linked that to Michelson-Morley being right, and used Emmy Noether's work to build his theories.
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Old 13th October 2014, 11:52 AM   #93
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Originally Posted by jsfisher View Post
Are these the same 9 videos you promoted in that other thread? The same videos that conflate velocity and position for the express purpose of supporting a nonsense result? Those videos?
No wonder I couldn't follow the conversation, no videos. Who needs math when youtube is out there!
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Old 13th October 2014, 12:07 PM   #94
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Originally Posted by Big Al View Post
...Maxwell's work threw out the value of c: the kinetic energy of a photon was shown to be 1/2 mc2...
That's not quite right: Maxwell had no idea about photons (his was purely a classical field theory, with waves in the field propagating at c). The discovery of photons came a while later, via Planck and Einstein.

Also, the kinetic energy of a photon isn't (1/2)mc2. That's the Newtonian (non-relativistic) K.E. formula for a particle of mass m going at c, which doesn't apply to photons (which are highly non-non-relativistic ). For photons you instead have E = pc, with p the momentum, or E = hf, with f the frequency and h Planck's constant.
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Old 13th October 2014, 12:17 PM   #95
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Originally Posted by ctamblyn View Post
For photons you instead have E = pc, with p the momentum, or E = hf, with f the frequency and h Planck's constant.
Just out of curiosity, is that the same E? In other words, can you say pc=hf, and the permutations thereof?
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Old 13th October 2014, 12:22 PM   #96
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Originally Posted by Hellbound View Post
Just out of curiosity, is that the same E? In other words, can you say pc=hf, and the permutations thereof?
Yes, you can. You can use that to derive p = h/λ, where λ is the photon's wavelength (this is just de Broglie's formula).
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Old 13th October 2014, 12:26 PM   #97
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Originally Posted by Gord_in_Toronto View Post
Whining about reality is pointless.
Originally Posted by Spindrift View Post
But it's easy and there's no math.
"It's easy to sit there and say you'd like to have more money. And I guess that's what I like about it. It's easy. Just sitting there, rocking back and forth, wanting that money." - Jack Handy
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Old 5th November 2014, 08:52 AM   #98
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Originally Posted by asydhouse View Post
I can't be arsed to faff about trying to quote his quote, but I noticed the OP seems to think that Relativity says that "mass increased as added velocity decreased".

But I have it in my mind that mass increases exponentially as you approach the speed of light, and that's why it's impossible to accelerate an object with mass to the speed of light c.

So, the OP seems to have got that wrong anyway. Can anyone comment on this?
Also, the law of acceleration prohibits it. This is easy to demonstrate by using the example of a car.

When you start moving a car from a parked position it takes comparatively little energy to accelerate a car faster, but the faster you are going the more energy it will take to accelerate the car faster. Eventually the energy required to accelerate faster will increase to the point you'll essentially need an infinite amount of energy to do so.

Both the energy required and the strange mass increases are some of the reasons why you would need something like a warp drive to accomplish faster than light travel.

Newtonian (not Einsteinian) physics wins again.

Edited to add: I have a question here. Why are people so intent on proving Einstein wrong?
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Old 5th November 2014, 09:32 AM   #99
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Originally Posted by Ziggurat View Post
More on the glory of this undersea nightmare:
http://theoatmeal.com/comics/mantis_shrimp
You still don't know what you're dealing with. The perfect organism. Its structural perfection is matched only by its hostility.

I admire its purity. A survivor... Unclouded by conscience, remorse, or delusions of morality.
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Old 5th November 2014, 03:57 PM   #100
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Originally Posted by Mudcat View Post


Edited to add: I have a question here. Why are people so intent on proving Einstein wrong?

In TV trope speak it is called the Worf effect.

http://tvtropes.org/pmwiki/pmwiki.ph.../TheWorfEffect

If you need to show how tough new and unknown character is you have them put a hurt'n on a well established badass.

Einstein serves that purpose in the scientific square circle. A well known and popular brainiac, take him down to establish your intellectual street cred. Unfortunately, it just ends up showing everyone how little you spent on your "poser" tattoo.
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Old 7th November 2014, 03:54 PM   #101
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Originally Posted by Senex View Post
I saw the documentaries -- special relativity came to Einstein in a flash while he was taking the train. If I didn't have to do my own driving I might have had more moments of brilliance. Also, many of us don't have an army of graduate student minions to do our math for us, fourth grade math not always a genius's strength.

Really? All of special relativity? Everything that Einstein wrote about in his 1905 paper? All of it?

Better: You could come up with a useful theory, the whole thing, if society would simply give you a chauffeur? Like there are all these great ideas that pop out of your imagination all the time.

You also imply that geniuses often can't do fourth grade arithmetic. Was that when you dropped out of school?-)

Einstein did not have graduate minions do his work for him. Sometimes professors do great work by means of a great staff. However, it happens not to be the case with Einstein.
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Old 7th November 2014, 04:04 PM   #102
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Senex has admitted in the Member's only section that his posts denying relativity in this thread were only a "joke" and were not meant to be taken seriously. I will leave it to you if you believe this to be funny or not.
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Old 7th November 2014, 04:21 PM   #103
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Originally Posted by Senex View Post
..........Einstein wrote his greatest paper, not while working with conventional wisdom thinkers at a University, but on his own during the train ride home from the patent office.........
It was a tram, not a train.
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Old 7th November 2014, 09:47 PM   #104
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Originally Posted by Giordano View Post
Senex has admitted in the Member's only section that his posts denying relativity in this thread were only a "joke" and were not meant to be taken seriously. I will leave it to you if you believe this to be funny or not.
I apologize. I am just a Poe boy.
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Old 11th November 2014, 11:01 AM   #105
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Originally Posted by Giordano View Post
Senex has admitted in the Member's only section that his posts denying relativity in this thread were only a "joke" and were not meant to be taken seriously. I will leave it to you if you believe this to be funny or not.
My posts always acknowledged the brilliance of relativity and were meant to be taken seriously at face value until they were thought through, pretty easily, I think.

The funniest part is in AAH. Can we link to threads in the AAH section?

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Old 11th November 2014, 12:11 PM   #106
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Originally Posted by Senex View Post
My posts always acknowledged the brilliance of relativity and were meant to be taken seriously at face value until they were thought through, pretty easily, I think.

The funniest part is in AAH. Can we link to threads in the AAH section?
So these were meant to be jokes, but only later after further thought? Sort of like time bombs?

I honestly don't know if you can link to AAH, but if you are very proud of your efforts that were place in AAH you can ask a moderator, I suppose.
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Old 11th November 2014, 12:13 PM   #107
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Originally Posted by Mudcat View Post
You still don't know what you're dealing with. The perfect organism. Its structural perfection is matched only by its hostility.

I admire its purity. A survivor... Unclouded by conscience, remorse, or delusions of morality.
I can't lie to you about your chances, but... you have my sympathies.
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Old 11th November 2014, 08:21 PM   #108
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Originally Posted by Belz... View Post
I think the point might be that we would naysay Einstein until he finally came up with the whole theory and presented it, assuming he'd come to a web forum to gloat that he overturned Newtonian physics.
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Old 12th November 2014, 12:07 AM   #109
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Originally Posted by Reality Check View Post
This sounds like a total misinterpretation of Feynman because he would not have been as stupid to literally say that. The easily understood laws of Special Relativity state that if you accelerate an object it will appear to gain mass (relativistic mass) and that if you bring it back to rest, it will have the same mass as when you started.
I have a limited understanding of SR, so if I make some fundamental errors please correct me.

As I understand it, if we observe an object with mass accelerating closer and closer to c, it will simultaneously gain mass and lose length in the direction of travel. Because of this, the objects density should increase. So if you accelerate an object enough would it eventually become so dense that it collapses onto itself and forms a black hole?

I think the answer should be no because one observer's perspective could show the object collapsing while another's wouldn't, but I don't know enough to know why not.
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Old 12th November 2014, 07:35 AM   #110
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Originally Posted by Unlike a Bull View Post
I have a limited understanding of SR, so if I make some fundamental errors please correct me.

As I understand it, if we observe an object with mass accelerating closer and closer to c, it will simultaneously gain mass and lose length in the direction of travel. Because of this, the objects density should increase. So if you accelerate an object enough would it eventually become so dense that it collapses onto itself and forms a black hole?

I think the answer should be no because one observer's perspective could show the object collapsing while another's wouldn't, but I don't know enough to know why not.
Your question is reasonable, but no, it won't turn into a black hole.

First off, whether or not an object is a black hole is and must be reference-frame independent. If light can escape an object in one reference frame, it can escape an object in all reference frames, because different observers will not disagree about whether or not events occur, they'll only disagree about where and when. So we know that, whatever the details of why, a mass cannot turn into a black hole because of a change in reference frames.

OK, fine, but the mechanism still matters. We can't simply declare that this must be the answer without being able to derive it, After all, the theory must be at least self-consistent, so if we have stumbled upon an internal inconsistency, the theory is shot. So that's not the end of the discussion.

Now, a full calculation of the gravitational field of a moving mass will require general relativity. And general relativity is a bitch. The math is rough. In brief, the field will get squished along the direction of motion. But they key point is that the field, although it's affected by velocity, is still determined basically by the invariant mass, not the relativistic mass. So no black holes created by moving your object super-fast.

Which brings us back to the question of what relativistic mass is to begin with. Well, it's basically the energy, scaled by c-2 to turn it into units of mass. It's not the gravitational mass. So why use it at all, if it's just redundant with energy? Well, that's somewhat of a historical accident, and in fact most modern textbooks on special relativity don't even use it. Relativistic mass gained popularity as a concept because it makes certain mechanics equations (such as p = mv) look superficially the same in special relativity and Newtonian mechanics.

But that's not really a very good reason to use it. First, from a pedagogy perspective, masking the differences between relativistic mechanics and Newtonian mechanics is likely to lead to errors, not produce enlightenment. Second, it doesn't even work for all mechanics equations. For example, you cannot use F=ma in relativity, not even with relativistic mass. Turns out that at relativistic velocities, if you apply a force in a direction other than the one the mass is already moving, the acceleration vector won't be parallel to the applied force. Third, as you have discovered, it won't work with gravity.

tl;dr version: don't bother using relativistic mass.

You can do everything you want to do with invariant mass (aka rest mass), and you're less likely to make mistakes. Momentum no longer scales linearly with velocity when you use invariant mass, but that's really not a problem.
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Old 12th November 2014, 09:11 AM   #111
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Originally Posted by Unlike a Bull View Post
I have a limited understanding of SR, so if I make some fundamental errors please correct me.

As I understand it, if we observe an object with mass accelerating closer and closer to c, it will simultaneously gain mass and lose length in the direction of travel. Because of this, the objects density should increase. So if you accelerate an object enough would it eventually become so dense that it collapses onto itself and forms a black hole?

I think the answer should be no because one observer's perspective could show the object collapsing while another's wouldn't, but I don't know enough to know why not.
Your hypothesis is probably based on the Kerr solution to general relativity. The Kerr solution is a model of a black hole which initially hypothesizes certain conditions in the rest frame of the center of mass of a massive body. The body has to have a mass distribution in the rest frame is distributed isotropically around a single point in a rest frame of the center of mass. The density of this hypothetical mass distribution is above a limit here called the Kerr density.

If these conditions are met, there is an event horizon at a distance referred to as the Kerr radius. This mass with the event horizon is by definition a black hole.

If a small body is moving close to the speed of light in a specified inertial frame, then that inertial frame can't be the rest frame of the body. The density of the body in the rest frame of its center of mass would be less than the Kerr density limit. The density in the laboratory inertial frame can be much higher than the density in the center of mass frame. However, the Kerr solution requires that the density by higher than the Kerr limit in the rest frame of the bodies center of mass.

The problem is that traditional density is not invariant to the Lorentz transformation. In order for the density to be consistent with relativity, it has to be part of one component in a relativistic 4-vector. In other words, the density has to be embedded in a four dimensional vector with the current density. So you have to take into account the current density of the massive body in addition to the density.

So formally, the event horizon has to vary with both mass density and current density. The usual formula for the Kerr limit is an approximation that only applies in rest frames where the current density is negligible. Note that I am talking about mass current, not charge current.

I will make a simpler explanation using a rather mediocre model. One can approximate general relativity by special relativity under conditions where there is no source term for gravity. In other words, there is no large mass that generates gravity independent of acceleration. Of course, this is an invalid model in the case of a black hole. However, I think it is revealing.

Consider an inertial frame where a massive body is moving close to the speed of light. We will use special relativity, not general relativity. The has a gravitational field consistent with Newton's Laws of gravity in this rest frame. However, it also generates a gravimagnetic field.

Special relativity requires that there be a magnetic field that complements the electric field. However, it also requires that there be a gravimagnetic field that complements the gravitational field. The gravimagnetic field generated by the rapidly moving body resists objects that are falling into this high speed body. Just as a free electron starts to move in circles as it approaches a wire with high current, an object falling into the high speed body will also start to go in circles. So the rapidly moving object is not completely black unless it is a true black hole.

A true black hole will have a gravitational pull that exceeds the gravimagnetic force as it gets closer. So a rapidly moving black hole will suck up objects that get close even at high speed. However, this does not hold true for a body with a low rest density.


In general relativity, there is a phenomenon referred to as a Thirring effect or space-time dragging. However, it has an analog in the gravimagnetic effect.

Let me say that the special relativity limit of general relativity is well known to be a mediocre approximation. I am presenting it as a heuristic, not as a formal answer.

I was thrown out of one forum where I used this heuristic to answer questions. Please, I know very well it is just a heuristic. Please don't dump me !-)
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Old 12th November 2014, 09:37 PM   #112
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Originally Posted by Ziggurat View Post
Now, a full calculation of the gravitational field of a moving mass will require general relativity. And general relativity is a bitch. The math is rough. In brief, the field will get squished along the direction of motion. But they key point is that the field, although it's affected by velocity, is still determined basically by the invariant mass, not the relativistic mass. So no black holes created by moving your object super-fast.
Thanks for taking the time to reply. So basically the shape of the gravity well changes, but it's magnitude stays the same? Would the shape look different to different reference frames?

Quote:
tl;dr version: don't bother using relativistic mass.

You can do everything you want to do with invariant mass (aka rest mass), and you're less likely to make mistakes. Momentum no longer scales linearly with velocity when you use invariant mass, but that's really not a problem.
Alright. Interesting that relativistic mass has fallen by the way-side. Seems like a logical following from E=m*c*c.

Well thanks again for the reply. I need to do some more reading to wrap my head around this.
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Old 12th November 2014, 10:20 PM   #113
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Originally Posted by Darwin123 View Post
Your hypothesis is probably based on the Kerr solution to general relativity.
Hypothesis is too strong a word for what I had. "Question" would be more fitting.

Quote:
The Kerr solution is a model of a black hole which initially hypothesizes certain conditions in the rest frame of the center of mass of a massive body. The body has to have a mass distribution in the rest frame is distributed isotropically around a single point in a rest frame of the center of mass. The density of this hypothetical mass distribution is above a limit here called the Kerr density.

If these conditions are met, there is an event horizon at a distance referred to as the Kerr radius. This mass with the event horizon is by definition a black hole.

If a small body is moving close to the speed of light in a specified inertial frame, then that inertial frame can't be the rest frame of the body. The density of the body in the rest frame of its center of mass would be less than the Kerr density limit. The density in the laboratory inertial frame can be much higher than the density in the center of mass frame. However, the Kerr solution requires that the density by higher than the Kerr limit in the rest frame of the bodies center of mass.
I'm with you, so it's the density in the non-inertial reference frame that determines if something is above or below the Kerr limit.

Quote:
The problem is that traditional density is not invariant to the Lorentz transformation. In order for the density to be consistent with relativity, it has to be part of one component in a relativistic 4-vector. In other words, the density has to be embedded in a four dimensional vector with the current density. So you have to take into account the current density of the massive body in addition to the density.
You lost me. I think you're saying that density is dependent on the three spacial dimensions and time, which makes sense. But the only time I've heard the term current density is in fluid dynamics... and I don't think you're talking about that.

Quote:
So formally, the event horizon has to vary with both mass density and current density. The usual formula for the Kerr limit is an approximation that only applies in rest frames where the current density is negligible. Note that I am talking about mass current, not charge current.

I will make a simpler explanation using a rather mediocre model. One can approximate general relativity by special relativity under conditions where there is no source term for gravity. In other words, there is no large mass that generates gravity independent of acceleration. Of course, this is an invalid model in the case of a black hole. However, I think it is revealing.

Consider an inertial frame where a massive body is moving close to the speed of light. We will use special relativity, not general relativity. The has a gravitational field consistent with Newton's Laws of gravity in this rest frame. However, it also generates a gravimagnetic field.

Special relativity requires that there be a magnetic field that complements the electric field. However, it also requires that there be a gravimagnetic field that complements the gravitational field. The gravimagnetic field generated by the rapidly moving body resists objects that are falling into this high speed body. Just as a free electron starts to move in circles as it approaches a wire with high current, an object falling into the high speed body will also start to go in circles. So the rapidly moving object is not completely black unless it is a true black hole.

A true black hole will have a gravitational pull that exceeds the gravimagnetic force as it gets closer. So a rapidly moving black hole will suck up objects that get close even at high speed. However, this does not hold true for a body with a low rest density.


In general relativity, there is a phenomenon referred to as a Thirring effect or space-time dragging. However, it has an analog in the gravimagnetic effect.

Let me say that the special relativity limit of general relativity is well known to be a mediocre approximation. I am presenting it as a heuristic, not as a formal answer.

I was thrown out of one forum where I used this heuristic to answer questions. Please, I know very well it is just a heuristic. Please don't dump me !-)
Thank you for trying to explain all this to me, but I'm afraid it went right over my head. I wish I had a better response, I'm going to need to do some research on relativity before I can even ask meaningful follow up questions.
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Old 13th November 2014, 06:58 AM   #114
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Originally Posted by Unlike a Bull View Post
Thanks for taking the time to reply. So basically the shape of the gravity well changes, but it's magnitude stays the same? Would the shape look different to different reference frames?
Yes, the shape looks different in different reference frames. The magnitude changes at different places, so in some places it increases and some places it decreases, but it never turns into a black hole.

Quote:
Alright. Interesting that relativistic mass has fallen by the way-side. Seems like a logical following from E=m*c*c.
Sure, that works, but you don't need that expression. You can use E2 = m2c4 + p2c2 instead, where m is the invariant mass. In the case of zero velocity (p=0), that obviously reduces to the more familiar E = mc2, but it works at nonzero velocity without needing to introduce relativistic mass. It also works for massless particles like photons. Because the velocity and momentum dependence of relativistic mass is complex, this form also makes understanding the ultra-relativistic limit much more obvious. For massless particles, energy scales linearly with momentum, and even for massive particles, energy scales almost linearly with momentum if the particle is traveling fast enough (p >> mc). So from the perspective of learning the subject, E2 = m2c4 + p2c2 where m is invariant mass is, I believe, still preferable to E = mc2 where m is relativistic mass. But the latter looks so simple (since it hides more of the complexity), so it's rather tenacious in the public consciousness.
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Old 16th November 2014, 08:45 PM   #115
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Originally Posted by Unlike a Bull View Post
I'm with you, so it's the density in the non-inertial reference frame that determines if something is above or below the Kerr limit.
I think it is great that you decided to study relativity on your own. However, maybe I can provide a helpful hint before you start. The first thing you should try to learn is how to distinguish an inertial frame from non inertial frame.



It is not the density in a non inertial reference frame that determines whether it is at the Kerr limit. It is the density in the inertial frame where the center of mass of the body isn't moving.

Reference frames are determined by the hypothetical observer, not the body being examined. The density of the body will be different in every reference frame. The density of the body will be smallest in the reference frame where the center of mass of the body is not moving. If the sum of real forces acting on the body is zero, the that reference frame is an inertial frame.

We have only been talking about inertial frames of reference.

You are implicitly assuming that the body being observed does not have real forces acting on it. Therefore, the reference frame where the center of mass is not moving is an inertial frame. The formulas that describe a black hole are simplest for observers in this inertial frame.


If the body is spherical and exceeds a certain average density in the reference frame where the center of mass is not moving, then the object will be a black hole in all reference frames.

I promised a hint to help you study relativity. My hint: before you apply relativity to a problem you should try to understand what forces are acting on what bodies. The forces will help you decide what objects are part of an inertial frame and which are part of a non inertial frame.

I found that I can do a relativity problem best after I draw a force diagram for the way I learned it in Newtonian physics. Once I know what objects are apply force to which other forces, I can decide which reference frames are inertial and which are not inertial.

Wheeler wrote a famous textbook on 'General Relativity' called 'Gravity'. He starts out saying that there are not forces in relativity. Although this may be true in very narrow sense, I think this statement is confusing to beginners. Forces are everything in relativity as they are in all branches of physics !-)
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Old 22nd November 2014, 09:51 AM   #116
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Originally Posted by Mudcat View Post

Edited to add: I have a question here. Why are people so intent on proving Einstein wrong?
The over promotion of Einstein as a genius has prompted a great over reaction. Note that I am speaking as a great fan of all the pioneers in the 'New Physics'. I think I understand some of it. I have argued against the anti relativist cranks intensely over a long time. However, I think I understand some of the emotional dynamics of this retain.

Einstein has been over promoted as the greatest genius of all time. When I was young, many nonscientists in book and article presented relativity as the greatest intellectual achievement of all time. These probably didn't understand it themselves, but this is how they presented it. He was associated with the invention of 'atomic energy', which was and is a very important topic at the time.

The formula E=mc^2 was said to have been the major key to unlocking nuclear power. Also, Einstein was credited with having invented that formula for the first time. Neither claim is precisely true, though there is a small truth embedded in the claims (very small). His letter to Roosevelt was said to have convinced the President to push the nuclear bomb project. Ironically, this letter was more political than scientific so it didn't really show genius. However, nonscientists conflated the letter with the formula 'E=mc^2', which was in turn conflated with the entire nuclear bomb project.


So the partial truth in the antiEinstein claims was that Einstein was over promoted as a genius. Strangely, Einstein was also 'over promoted' as being illiterate. Einstein was not a polymath. he did poorly in some subjects. He had to work on some subjects in school to get through. So there was also a legend that he was dyslexic. Stories abounded about all the things he had difficulty in. He had difficulty in foreign languages (who doesn't?).

Einstein was a late bloomer in mathematics, sort of like Beethoven in music. So in the same sense you could say Beethoven wasn't a musical genius, you could say that Einstein wasn't a mathematics genius. After all, all geniuses have to bloom early. Right ?-)

Which brings us to antiJudiasm, which is a major contributing factor. One of the reasons Einstein was over promoted was because the Jewish community overprinted him. Much of it was defensive. They had been persecuted over the decade of WWII because they were genetically inferior. They were killed largely due to the myth they were genetically incapable of constructive thinking. They can only promote lies, according to Hitler! So Einstein was promoted as a case of the exact opposite. He supposedly shows how Jews were superior to other people in creative enterprises, especially Germans.

The irony is that Einstein was also German. Many of the geniuses who started the 'New Physics' were German. In fact, some people in England were initially skeptical of Einstein because he was German! There were big antiGerman feeling in England and America. Einstein faced prejudice against Germans! So scientists in these countries were inclined to do more experiments to prove those pointy haired Germans wrong. To the credit of English and American scientists, those experiments ended up proving Einstein right.


People who are defensive about their lack of mathematics activity like to compare themselves to Einstein. After all, they have uncontrollable impulse that they can't follow up on. They can write down formulas at the drop of a hat, right? No one gives them credit for rambling on and on. Many of them are real dyslexics.

Many of these dyslexics are also anti Jewish. Racism is almost universally a grass roots movement. They emphasize the virtues of the 'common man'. The common man in their view tends to be a semiliterate. So anti Jewish racists who are also scientifically and historically deficient tend to attack Einstein, the icon of Jewish genius. Of course, Jewish illiterates do much the same thing. However, they don't know relativity or any science either. So they don't defend Einstein all that well. The nonJewish illiterates have an unfair advantage !-)

Although not all 'anti relativists' are antiJewish, there are a great number who are. Many of the emotional antiEinstein cranks are antiJewish. They are very loud and obnoxious.

Of course, there are legitimate scientists working on experiments to falsify relativity. I met some Chinese scientists at a university about ten years ago attempting some incredibly-precise optical-experiment to show that space is not truly anisotropic. They had miles of fiber optic cable in a room that was specially designed to be vibrationally isolated. I haven't heard about them since. I guess it didn't pan out, but I am not sure. I seriously doubt there was any prejudice associated with their work. Personally, I hope to hear about them one way or another. However, their effort is know right now to a very few. Hurray for China, which funded them!

<Note that I don't support China in all her endeavors. However, I appreciate truly innovative research. So let me applause them on this, at least!>

Which brings me back to Beethoven.

Bethoven was a musical moron! All those rumors that I am tone deaf are lies lies by the Beethoven cult! I have musical genius that no one recognizes even though I can't hold a note! I can bang out four notes repeated again and again! I used to sing as a child in a choir! I bet Beethoven never did that! And Beethoven had this wild hair! I don't have wild hair! And Beethoven was German! The Germans are always promoting their 'hero', Beethoven! The Germans are always trying to take credit from the Jews! This is why they can't recognize a real musical genius like Barbara Streisand !-)

Last edited by Darwin123; 22nd November 2014 at 09:55 AM.
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