Serious Scientific Answers to Absurd Hypothetical questions

[kerbiloid]

m = m₀/sqrt(1-(v/c)²)

A square root gives two results: + and -.

Does it mean that any thing in the Universe has its evil twin with a negative mass?

Why do we ignore the second root? Just because we dislike it?

[wumpus]

On 12/27/2018 at 4:51 AM, kerbiloid said:

m = m₀/sqrt(1-(v/c)²)

A square root gives two results: + and -.

Does it mean that any thing in the Universe has its evil twin with a negative mass?

Why do we ignore the second root? Just because we dislike it?

My understanding is that "relativistic mass" isn't very useful.  As v approaches c, you shouldn't create a black hole, regardless of your "relativistic mass".  It does work fine for momentum, but I think the whole idea was dropped after Einstein created general relativity.

Still E²=m²c⁴shouldn't have the roots taken on both sides while ignoring the obvious sign possibilities (this is from Einstein's derivation of his famous equation).

Edited December 29, 2018 by wumpus
*relatavistic* mass was critically left out, ruining what I was trying to say.

[kerbiloid]

1 hour ago, wumpus said:

My understanding is that "mass" isn't very useful.  As v approaches c, you shouldn't create a black hole, regardless of your "relativistic mass".  It does work fine for momentum, but I think the whole idea was dropped after Einstein created general relativity.

Still E²=m²c⁴shouldn't have the roots taken on both sides while ignoring the obvious sign possibilities (this is from Einstein's derivation of his famous equation).

Here the mass is not essential, as the relativistic factor effects also length, time and so on.

Just why do we exclude one of the roots intuitively, on a whim. Why do we just say "no negative root". Maybe there are both.

Edited December 28, 2018 by kerbiloid

[Green Baron]

Well, how much sense make -2 (very fast) apples ?

[kerbiloid]

8 hours ago, Green Baron said:

Well, how much sense make -2 (very fast) apples ?

The relativistic factor doesn't effect amount of pieces.

[Steel]

13 hours ago, kerbiloid said:

Here the mass is not essential, as the relativistic factor effects also length, time and so on.

Just why do we exclude one of the roots intuitively, on a whim. Why do we just say "no negative root". Maybe there are both.

As far as I understand it, the negative root is still valid from a purely theoretical standpoint (as it is in many equations) however we have no evidence for negative masses, and many cosmological theories do not allow for it, so the root is ignored.

[kerbiloid]

12 minutes ago, Steel said:

As far as I understand it, the negative root is still valid from a purely theoretical standpoint (as it is in many equations) however we have no evidence for negative masses, and many cosmological theories do not allow for it, so the root is ignored.

That's so.
Though iirc usually in any equation having several solutions, or in the trigonometric functions, all of them are considered as valuable.
But in this case we just omit the negative sign solution, while not arguing its correctness.

But if presume that both answers are correct, and that it means that any thing has a counterpart with the parameters of the opposite sign, then we get the existence of two absolutely similar sides of the Universe, with total mass, energy, impulse, and so on by definition equal to zero.

Edited December 29, 2018 by kerbiloid

[Green Baron]

4 hours ago, kerbiloid said:

The relativistic factor doesn't effect amount of pieces.

How much sense make -2 apples, a duration of -2 seconds or a distance of -2 centimeters ?

Only the speed in the term may be negative (moving the other direction then) but it does not matter because it is squared.

[kerbiloid]

Just now, Green Baron said:

, a duration of -2 seconds or a distance of -2 centimeters ?

Just an opposite direction of relative values.

1 minute ago, Green Baron said:

-2 apples

Again, amount (an absolute value) isn't effected.

[Green Baron]

5 minutes ago, kerbiloid said:

Though iirc usually in any equation having several solutions, or in the trigonometric functions, all of them are considered as valuable.

Depends on the use case. If that is the case we can use the |x| operator. In geometry for example a minus usually makes no sense. Or, when computing matrices and vectors for graphics stuff then minus make no sense, we don't look at that case.

Quote

But if presume that both answers are correct, and that it means that any thing has a counterpart with the parameters of the opposite sign, then we get the exitsence of two absolutely similar sides of the Universe, with total mass, energy, impulse, and so on by definition equal to zero.

Theroretically, yep. Imagine the possibilities :-)

2 minutes ago, kerbiloid said:

Again, amount (an absolute value) isn't effected.

Man, again, it is -2kg. If you don't like apples, take oranges :-)

Edited December 29, 2018 by Green Baron

[kerbiloid]

1 minute ago, Green Baron said:

If that is the case we can use the |x| operator.

Arbitrary. A negative root is still a root.

1 minute ago, Green Baron said:

In geometry for example a minus usually makes no sense.

In geometry minus almost always means an opposite direction of a vector, or a difference, or an angle.

2 minutes ago, Green Baron said:

Imagine the possibilities :-

That's what I did!

[Steel]

6 minutes ago, kerbiloid said:

But if presume that both answers are correct, and that it means that any thing has a counterpart with the parameters of the opposite sign, then we get the existence of two absolutely similar sides of the Universe, with total mass, energy, impulse, and so on by definition equal to zero.

This is why some physicists think parts of theoretical physics are loosing their usefulness.

People spend time making lots of very clever theories by looking only at the mathematics, but do not worry whether or not they actually relate to our universe.

[Green Baron]

4 minutes ago, kerbiloid said:

Arbitrary. A negative root is still a root.

Nobody doubts that but pls. try to understand: in many cases only one makes sense.

Quote

In geometry minus almost always means an opposite direction of a vector, or a difference, or an angle.

Only one makes sense.

Simple example: When you are calculating normals (for texturing, movement, lighting, ...), you can use only 1 of them (usually the positive) or you get a normal in the wrong direction which messes things up. The sign does matter as you say, but irl only one (usually) makes real sense.

Edited December 29, 2018 by Green Baron

[kerbiloid]

10 minutes ago, Green Baron said:

Nobody doubts that but pls. try to understand: in many cases only one makes sense.

Certainly.
But if we have particle of the rest mass m, and accelerate it to some velocity, we get two correct solutions of its current mass. None of them is preferrable except of a so-called "common sense".
So, either we should presume that a particle is in both states simultaneously, or there are two particles which compensate each other. As we can see, the latter is just a longer description of the former.

10 minutes ago, Green Baron said:

Simple example: When you are calculating normals (for texturing, movement, lighting, ...), you can use only 1 of them (usually the positive) or you get a normal in the wrong direction which messes things up.

I can use both, but should consider only similar ones at once. So, I get two (similar) solutions for normal and anti-normal vectors. They exist at once, but one of them is just practically excessive for me.

P.S.
Launch a particle - split the reality.

Edited December 29, 2018 by kerbiloid

[Gargamel]

16 hours ago, Steel said:

People spend time making lots of very clever theories by looking only at the mathematics, but do not worry whether or not they actually relate to our universe.

Without theory, there would be no experiment to test.    Without data from the experiment, there would be no way to refine the theory.   They go hand in hand.  You can't have one without the other. 

[Green Baron]

True, the scientific method.

let me add: as long as a theory has a connection to the real world. But some are impossible to test (M-theory, string theories) and in discussion of being too "meta" for real world relevance, and fizzling out. And some hypotheses are just guesses from blurry pictures (frequently the case in astronomy, especially planetary science) without a foreseeable possibility of being ever experimentally tested. And some experiments are simply too big for us to carry through. Few people have a black hole or a galaxy at hand :-)

So why do we ignore the mathematically correct minus result from the square root in some cases, it is because in these cases, they make no real world sense.

[Mad Rocket Scientist]

Maybe a more interesting question is why the positive square root does work, and so accurately describes the world. See: https://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.html

[Nuke]

On 12/29/2018 at 12:42 AM, kerbiloid said:

Just an opposite direction of relative values.

Again, amount (an absolute value) isn't effected.

i wonder if relativistic applesauce would go good on pork chops?

[wumpus]

On 12/29/2018 at 4:49 AM, Steel said:

This is why some physicists think parts of theoretical physics are loosing their usefulness.

People spend time making lots of very clever theories by looking only at the mathematics, but do not worry whether or not they actually relate to our universe.

Blame Einstein and the Maxwell Equations.  There was plenty of work trying to explain how the aether worked and how it related to our universe.  Then Einstein came along and took the equations at face value and showed them correct.  I think this played out a number of times in quantum mechanics for other physicists as well.

When the "clever math tricks" stop working, that's probably a good indication that there is something wrong with the equations you are using and they could use some work (but I'm really wary of declaring that E really should equal +/- mc²).

[kerbiloid]

Physics is just a visual representation of mathematics.

P.S.
I.e. when mathematicians get bored counting equations, they call it physics.
When physicists get bored counting atoms and particles, they call it chemistry.
When chemists get bored counting reactions, they call it biology.
When biologists get bored counting cells, they call it medicine.
When doctors get bored counting symptoms, they call it (forum rules 2.2 forbid some words).

Edited December 31, 2018 by kerbiloid

[Nivee~]

Woah, this discussion about negative stuff might just become the plotline of a sci-fi novel.. 

[DDE]

On 12/30/2018 at 12:10 PM, Green Baron said:

And some experiments are simply too big for us to carry through. Few people have a black hole or a galaxy at hand :-)

I’m still waiting to hear from the White House about testing Communism. Need to turn the United States into a totalitarian dystopia for a few decades.

[kerbiloid]

AI will equalize all.

[DDE]

4 hours ago, kerbiloid said:

AI will equalize all.

One is all, yes.

[kerbiloid]

Comrade AI...