How exactly does space/time fabric work?

Samwell Seed Well

Well-Known Member
sorry i keep forgeting the topic is photons, and get side tracked

photons , photons at rest have no mass, until a force is exerted on it

like gravity . .or a black hole and that is why light is warped like any other mass in a black hole

isd this correct i made a black hole post a fewe pages back



\frac{1}{r} e^{-\frac{m_\gamma c r}{\hbar}}

equation wont transfer nicely

"
It is not known absolutely for sure that photons do not have mass. However, there is an experimental upper limit on what that mass could be; and it's pretty darn small.

Additionally, if photons had mass, there should be a third possible polarization for light, and electrostatic potentials should fall off as
[FONT=MathJax_Main]1[/FONT][FONT=MathJax_Math]r[/FONT][FONT=MathJax_Math]e[/FONT][FONT=MathJax_Main]−[/FONT][FONT=MathJax_Math]m[/FONT][FONT=MathJax_Math]γ[/FONT][FONT=MathJax_Math]c[/FONT][FONT=MathJax_Math]r[/FONT][FONT=MathJax_Main]ℏ[/FONT]​
.

To understand the statement that even light can't escape from a black hole, you have to understand a little bit about how general relativity describes gravity.

General relativity says that the presence of mass (or energy or momentum or pressure, etc.) actually bends the fabric of space and time. When the path of a particle is affected by gravity it happens, not because the particle is feeling a force, but because the particle is travelling along what is effectively a straight line path on a curved surface. When you think about it this way, it seems natural that even light should be affected.

A black hole is simply the case where space and time are so bent that every single straight line path that exists leads to one single place. (Of course, to be exact, we should say that every path that exists inside the event horizon leads to one single place. Outside the event horizon, there are paths that don't lead into the black hole.)"
 

fb360

Active Member
sorry i keep forgeting the topic is photons, and get side tracked

photons , photons at rest have no mass, until a force is exerted on it

like gravity . .or a blach hole and that is why light is warped like any othe rmass in a black hoke
Yeah, photons are said to be "massless" at every state.

But yeah, my previous quote was not with respect to the object you mention, being a photon. I took it otherwise, because you mentioned weight being different afterwards. Can't have weight without mass.
 

Samwell Seed Well

Well-Known Member
p=mv

If the velocity is always zero then the momentum is always zero. If the "object has no mass" (which is absolutely ridiculous to say that an OBJECT has no mass) then the mass is zero AND the velocity is zero, and it goes without saying that the momentum is zero.


...and since p=mv, the equation you referred to when the object has a zero mass, E=pc, can be stated as E=(mv)c. Zero mass times zero velocity times the speed of light equals zero energy.
need some brakets there, and then your good, photons are mass less . . . .
 

Seedling

Well-Known Member
That is not true. We have mass, which remains semi-constant (except for when we take big shits :P).
Objects which do not have a force acting on them are said to be at rest, and have no momentum; they can still have mass. i.e (me in the middle of space, with only a very very weak force of gravity working on me).

F = ma.

No F = No A. NOT No F = no M
Name 1 object that doesn't have the force of gravity on them at all times? Failing to do so negates your "logic."
 

fb360

Active Member
That is not true. We have mass, which remains semi-constant (except for when we take big shits :P).
Objects which do not have a force acting on them are said to be at rest, and have no momentum; they can still have mass. i.e (me in the middle of space, with only a very very weak force of gravity working on me).

F = ma.

No F = No A. NOT No F = no M
very rarely do we speak about massless objects
Name 1 object that doesn't have the force of gravity on them at all times? Failing to do so negates your "logic."
What are you talking about? I posted NEWTONS equation which is logically sound.
Did you not even read my post. I clearly demonstrate that I comprehend the fact that gravity is always working..

In this term, has no force, also means having equal and opposite acting forces... As is always considered in physics...

I just don't get how you can tell me any of what I said was illogical, when half of my post was f=ma LOL

e;
PS, just to seal the deal.
High energy gamma ray particles ;). massless, yet destroy dna. BOOM
 

Seedling

Well-Known Member
need some brakets there, and then your good, photons are mass less . . . .
The mass of a photon is really neither here nor there. A photon has a velocity of c (299,792,458 m/s in a vacuum). Photons are "energy packets" so they must have a momentum greater than zero. A momentum greater then zero means the mass can't be zero.
 

Seedling

Well-Known Member
What are you talking about? I posted NEWTONS equation which is logically sound.

Did you not even read my post. I clearly demonstrate that I comprehend that fact..

In this term, have no force also means having equal and opposite acting forces... As is always considered in physics...

I just don't get how you can tell me any of what I said was illogical, when half of my post was f=ma LOL
No, Newton's equation isn't logically sound since you can't tell me of which object you are referring to that escapes the force of gravity.

f=ma is a NET FORCE. Do you know the difference between a force and a net force?
 

Samwell Seed Well

Well-Known Member
The mass of a photon is really neither here nor there. A photon has a velocity of c (299,792,458 m/s in a vacuum). Photons are "energy packets" so they must have a momentum greater than zero. A momentum greater then zero means the mass can't be zero.
mass of a photon is the topic currently, so i kinda thought it was relvent
 

Samwell Seed Well

Well-Known Member
The mass of a photon is really neither here nor there. A photon has a velocity of c (299,792,458 m/s in a vacuum). Photons are "energy packets" so they must have a momentum greater than zero. A momentum greater then zero means the mass can't be zero.
mass of a photon is the topic currently, so i kinda thought it was relvent

"It is not known absolutely for sure that photons do not have mass. However, there is an experimental upper limit on what that mass could be; and it's pretty darn small.

Additionally, if photons had mass, there should be a third possible polarization for light, and electrostatic potentials should fall off as
[FONT=MathJax_Main]1[/FONT][FONT=MathJax_Math]r[/FONT][FONT=MathJax_Math]e[/FONT][FONT=MathJax_Main]−[/FONT][FONT=MathJax_Math]m[/FONT][FONT=MathJax_Math]γ[/FONT][FONT=MathJax_Math]c[/FONT][FONT=MathJax_Math]r[/FONT][FONT=MathJax_Main]ℏ[/FONT]​



ill pots again

"To understand the statement that even light can't escape from a black hole, you have to understand a little bit about how general relativity describes gravity.

General relativity says that the presence of mass (or energy or momentum or pressure, etc.) actually bends the fabric of space and time. When the path of a particle is affected by gravity it happens, not because the particle is feeling a force, but because the particle is travelling along what is effectively a straight line path on a curved surface. When you think about it this way, it seems natural that even light should be affected.

A black hole is simply the case where space and time are so bent that every single straight line path that exists leads to one single place. (Of course, to be exact, we should say that every path that exists inside the event horizon leads to one single place. Outside the event horizon, there are paths that don't lead into the black hole.)"

what do you think about this^
 

fb360

Active Member
No, Newton's equation isn't logically sound since you can't tell me of which object you are referring to that escapes the force of gravity.

f=ma is a NET FORCE. Do you know the difference between a force and a net force?
LOL my goodness.

Do you understand f=ma at all? Rhetorical, no need to answer. Why are you in this section? Again you didn't even read my post you buffoon. Open your eyes and learn to read. You arent worth any further response.
 

guy incognito

Well-Known Member
You keep talking about an object being at rest, but you fail to explain what exactly you mean by that. At rest compared to what? There is one object in space and we want to know the momentum of the object. You assume the velocity of the object is zero, so how could you ever have a momentum greater than zero if the velocity of the object is always zero?

p=mv

If the velocity is always zero then the momentum is always zero. If the "object has no mass" (which is absolutely ridiculous to say that an OBJECT has no mass) then the mass is zero AND the velocity is zero, and it goes without saying that the momentum is zero.


...and since p=mv, the equation you referred to when the object has a zero mass, E=pc, can be stated as E=mvc. Zero mass times zero velocity times the speed of light equals zero energy.
For the jillionth time, it is at rest compared to the observer. If you are measuring something, or you have an instrument that is measuring something, and you/instrument is not ACCELERATING, then THAT is the frame that is at rest. Even if you are traveling close to the speed of light towards the edge of the universe. Or if you are traveling near the speed of light in the opposite direction. Or ANY other direction, and ANY other speed, so long as you are not accelerating.

There is no "object" we are speaking of. The object is a photon. It is not some physical object you can grab, and the size and speed we are talking about are intuitively impossible to understand. You have no experience with "objects" of that size or speed, so your intuition does not apply. What does appear to apply are the equations of relativity. By assigning a photon a particle like quality you can include it in the equations - and it works.

The velocity is not always zero. If you are measuring an object with zero velocity, then that means it is not moving relative TO YOU. If you are measuring it move relative to yourself, then you can assign it a value.

Remember all those posts when I said newtonian mechanics are not correct? They APPEAR to be correct at slow speeds? That's where your p=mv comes into play. The relativistic equations reduce to newtonian equations when v is significantly less than c. A photon is moving at c though, so the relativistic equations don't reduce to newtonian. The relativistic portion is overwhelmingly important at these speeds.
 

Padawanbater2

Well-Known Member
Has gravitational lensing been brought up yet?

How does Keynes explain that?

Clear evidence of space being warped by gravity.






 

Dr Kynes

Well-Known Member
yes... clear evidence that the universe is made of 2 dimensional graphics... just kidding i know what your getting at, but that sbeen all over this thgread. light DOES get pulled off course by gravity, and thats a problem, in fact its pretty much THE problem in this thread.

my contentioon is that the warping space thing being the cause of light's course change is a macguffin to explain the evidence, not a logical asssertio that can be proved or disproved by any testing method currently availiable.

i am always wary of untestable hypotheses, its very much like all those things "THEY dont want you to know" which invariably turn out to be a scam designed to prey upon the unwary, or perpetually baffled, but in a scientific sense, not a scam artist sense. and thats a huge difference.

scientists are currently looking for the mechanism that explains why photons are massless (which they MUST be to preserve other theories which currently seem to work real good) yet they are attracted by gravity, and space warping seems to fit in their models.

it however leaves me perplexed how a massless and otherwise inert area of space can alter the course of an object because mass (and gravity) are nearby. instead of gravity pulling at a photon (with zero mass they should be impervious to gravity) gravity now deforms the area around it (how does it effect the area with it's presumed massless nature?) and this deformed space alters the course of the photon (again, how does it do this?) which can now remain officially massless by dint of some fancy mathematical hocus pocus. the theories currently considered the fucking TITS bvy physics nerds tie everything up in a neat package, with a colorful quantum ribbon, and its just so neat and tidy, i gotta wonder where they hid the forces that make things interact when they are interacting with other shit to do other shit to finally do other shit in a complex non-newtonian game of Telephone

not bein a math whizz i cant express the ideas in the traditional language of physics so i must use words. and words dont work well in an area that prefers its own jargon. thats why mechanics have so much trouble figuring out what people are saying when their car makes some noise. the non-mechanics cant explain that they feel a jolting in their steering wheel when their front strut assembly cycles, that is in fact the rattling of a worn lower ball joint, and not a "noise" at all.

Edit: also,, im certain theirs a joke in there somplace about the pages of that astronomy book being stuck together. i can almost hear the joke, but it's escaping me.
 

guy incognito

Well-Known Member
Has gravitational lensing been brought up yet?

How does Keynes explain that?

Clear evidence of space being warped by gravity.
Yes it has. His theory is that newtonian mechanics are correct and that photons have mass, and are therefore attracted to massive objects which gives the illusion of space warping. Several of us have already pointed out that:

1. Newtonian equations are not correct. They don't work in extreme situations (such as light speed particles).
2. Einsteins equations do appear to be correct
3. If you use the upper limit mass of the photon instead of the assumed zero then neither set of equations works properly, which is problematic because:
3.1 we have tons evidence confirming relativity
3.2 we have tons of evidence confirming multiple other theories all which agree with a massless photon
4. He thinks it is an untestable hypothesis, even though it has been tested multiple times. He has a problem in that they cannot achieve infinite precision to say it is 100% for sure exactly zero

He admittedly does not understand the math involved, yet he somehow expects to have an intuitive understanding of how it fundamentally works. All of his questions and perplexed misunderstandings have been elegantly explained for over a hundred years.
 

mindphuk

Well-Known Member
scientists are currently looking for the mechanism that explains why photons are massless (which they MUST be to preserve other theories which currently seem to work real good) yet they are attracted by gravity, and space warping seems to fit in their models.
Either you are being purposely dishonest or extremely obtuse. No one has ever claimed photons must be massless to preserve any theories, they must be massless to conform to observation. If they are not massless, they cannot move at the speed of light. If they were not massless we would see frequency dependent speed in a vacuum. If they were not massless, Coulomb's law would deviate from the inverse square law we actually observe. You are dishonest to even imply that these are untestable problems as we have linked to examples of how these things are constantly being tested such as http://www.princeton.edu/~romalis/PHYS312/Coulomb Ref/TuCoulomb.pdf

You are being ignorant to imply that using math is somehow akin to jargon. Math is not jargon, it is the actual language of physics. The universe appears to be based in math. Math is used to uncover the hidden universe, it is not used to obscure its view from those unable to grasp it. The universe acts as a mathematical construct. Your ramblings hold as much water as the creationist that whines about evolution because he doesn't understand it. Your inability to grasp these fundamentals does not make you right and everyone that understands them part of the conspiracy. This is why I called you a science denier and no matter how much you disagree with that label, it fits, at least as far as these topics are concerned.
 

Doer

Well-Known Member
The basic problem for, K, is this. There is no experimental evidence for mass of a Photon.

To our best Understanding, and we have looked for his hoped for answer; Photons are not subject to gravity.

They may take a long time to get to the surface of the Sun, for example, but, they still emerge at Light Speed. They don't slowly attain Full Speed after sneaking thru the warped geodesic, they way they sneaked to the surface of the Sun after 100,000 Earth orbits.

No they are instantly at Light Speed after becoming un-encoumbered by matter....just like for a light bulb.

Yet, when we watch star light through this same space geodesic, the light follows the curve of space, in such a way, there is magnification. He can't explain that.

So, nattering about the math that is not understood, by him, and to try to ignore the experimental results, is Red Herring.

The math is not the thing. The experiments have to uphold the math. If they can be repeated by other's in the field, only then do the Experiments create the current, (only) Understanding.

There is plenty of competing math. Only one Understanding.

We should confine our discussion with the amateurs to the Experiments, only. Just my opinion.
 
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