JEROME - Black holes do not exist

[The Man]

Don't take a dump in the virtual punch bowl. I only brought up terminology to correct bad information in regards to gravitation, posted by others.

You are avoiding that conversation.

No, I was only dumping out the soiled punch after you pinched off some terminology into it.

Perhaps MM is distinguishing microgravity in the case of the ISS, as opposed to weightless. I fail to see that the objects inside the ISS are not essentiallly weightless, lacking weight, since they will register nothing on a spring scale. What experiment could distinguish this from items in a "no gravity" situation?

Actually MM is referring to the fact that the ISS is still influenced by the force of gravity, which is really what weight is (the force of gravity). The ISS is constantly accelerating towards (centripetal acceleration due to the centripetal force of gravity) the earth but never hits the earth (due to the ISSs tangential velocity). Although the astronauts in the ISS can not directly feel this weight or the force of gravity (from the earth), the fact that they can just look out a window and see that they are orbiting and not traveling in a “straight” trajectory tells them that they are under the influence of a gravitational field. Someone else also mention time dilation but that requires precise clock and communication, looking out the window is about the simplest experiment there is.

I don't really enjoy pointing out other peoples errors, they might just be having a bad day. Here is part of what started the terminology discussion. We can talk about CONCEPTS in regards to this if you wish.

Oh, please do, you will find the concepts more revealing then the terminology.

Maybe somebody should respond to the training tank example as well.

With neutral buoyancy, people and objects underwater are weightless (Ws). That is why it is used to train for the Wss of space.

Gravity isn't gone, it just doesn't matter. You will have no weight on a scale. Just like any other case where you are Ws.

No, absolutely not weightless at all, the fact that in buoyancy the weight of an object is supported by the weight of the volume of liquid it displaces makes gravity (and thus weight) doubly important. When the weight of an object equals the weight of the volume of liquid it displaces it is said to be neutrally buoyant. Although buoyancy tanks are a useful tool in training they do have some draw backs as the viscosity or the resistance of the liquid to motion detracts significantly from the freedom of motion one would experience in space.

Free fall, orbit, on your way to the moon, on your way out of the solar system, there are specific instances where we describe something or somebody as weightless. A scale shows no weight.


Mass is the same (ignoring realtive mass from velocity), but depending on the situation, you can be weightless. But not falling.

Free fall is a specific term for falling into a gravity well. The difference between that sort of Ws and the others, is you are accelerating the entire time. In water, in orbit, in outer space, you are not accelerating, but there is no gravity. Zero-G

Now back to that Black Hole ...

But in an orbit you are still moving under or always accelerating (changing direction or momentum) due to the force of gravity. It is specifically that force which we define as “weight”.

 

[lenny]

But in an orbit you are still moving under or always accelerating (changing direction or momentum) due to the force of gravity. It is specifically that force which we define as “weight”.

ummm, but if i am standing on the surface of a stationary solid sphere with the radius of the earth and the mass of jupiter, i am not changing direction or momentum.

yet i fear i would neither be nor feel weightless.

if you find a balance under the equivalence principle, then do details regarding distinguishing acceleration in space and stationarity in a gravitational field really matter?

 

[robinson]

No, I was only dumping out the soiled punch after you pinched off some terminology into it.

Nonsense. I'm trying to clear the mess you and a couple of others are making. Like this:

It is really a question of the observer's frame of reference - from the FoR inside the ISS they observe weightlessness, but from the FoR on the Earth we observe them in free-fall.

Free fall has a specific meaning, and it is not what the ISS is doing. It is in orbit. It would be just as wrong to say the moon is in free fall. Nonsense talk.

Actually MM is referring to the fact that the ISS is still influenced by the force of gravity, which is really what weight is (the force of gravity).

Nope. You just confused things even more. And you are adding to the "force" problem. According to GR there is no force. It is warped spacetime, not a force.

But to the MM mess, everything is influenced by gravity, all the time. The ISS is weightless, the astronauts are weightless, if you attach a scale to anything in orbit, there is no force of gravity, no weight. This is the prime confusion here. You are looking at gravity like a magnetic field or something.

It doesn't work like that at all. The ISS is influenced by the sun and moon and Jupiter as well, but the gravity of all those bodies doesn't matter (except for really small tidal forces). Nobody weighs anything onboard. It is Wss, they are Ws.

Although the astronauts in the ISS can not directly feel this weight or the force of gravity (from the earth), the fact that they can just look out a window and see that they are orbiting and not traveling in a “straight” trajectory tells them that they are under the influence of a gravitational field.

You could say the same thing if they look at the sun. It is influencing them as well. But they are weightless. If they were twice the distance from the earth as the moon, either in orbit, or not, they would still be weightless. Zero-G.

This is why I said there are some major misunderstandings about gravity going on in this thread. You can blast off so you are not even in orbit around the earth anymore, and you are still in orbit around the sun. But you don't feel anything, much less consider your ship in free fall.

You are now in orbit around the sun. Blast off away from the sun (Voyager), and now you are in orbit around the center of the galaxy. Still the exact same situation onboard. If you are not accelerating, no gravity.

If you go with the nonsense being spouted here, you would say Voyager isn't really in zero-G, it is in free fall around the center of the Milky Way! It is accelerating because it is in orbit around the Galactic center!

Stop pinching.

 

[The Man]

ummm, but if i am standing on the surface of a stationary solid sphere with the radius of the earth and the mass of jupiter, i am not changing direction or momentum.

yet i fear i would neither be nor feel weightless.

But standing on that sphere you are not orbiting that sphere are you? Yet you do still experience the force of gravity it is just that force is being opposed by the sphere you are standing on, release a trap door underneath you (or remove that counter force) and your momentum will change, rapidly.

if you find a balance under the equivalence principle, then do details regarding distinguishing acceleration in space and stationarity in a gravitational field really matter?

They certainly matter if you are trying to accelerate through space and not be stationary in a gravitational field (or visa versa).

 

[Hellbound]

robinson:

http://www.nasm.si.edu/exhibitions/gal109/LESSONS/TEXT/FREEFALL.HTM

Orbits, like most space travel, are a type of free fall.

http://www.nap.edu/html/oneuniverse/motion_48-49.html

With this intuitive leap, Newton realized that all orbits in the solar system are never-ending free falls.

http://www.astro.virginia.edu/class/oconnell/astr121/guide08-s04.html[/url\]

Free motion in response to gravity (in the absence of other forces) is called "free-fall" motion. All four types of conic section orbits are free-fall.

[URL]http://hyperphysics.phy-astr.gsu.edu/Hbase/orbv2.html

A person feels weightless in orbit simply because he or she is in free fall along with the satellite and experiences no force of support from the satellite.

http://www.lasalle.edu/~smithsc/Astronomy/Orbits/orbits.html
http://science.nasa.gov/msL1/ground_lab/msl1freefall.htm

A spacecraft does the very same thing the broken elevator does - it falls toward Earth due to gravitational attraction, but is moving fast enough, and in the right direction (i.e. away), to miss hitting it, thanks to the rockets used to launch it.

https://aerospacescholars.jsc.nasa.gov/HAS/cirr/ss/3/mission.cfm

True, the astronauts are experiencing weightlessness, but they are not experiencing a true zero-g environment. The astronauts are experiencing weightlessness because they are in free fall.

http://exploration.grc.nasa.gov/education/rocket/ffall.html

On the figure, we show an orbiting Space Shuttle and a space walking astronaut. The astronaut and the Shuttle have very different weight, size and shape. But objects in orbit are in a free fall and the only force acting on the objects is the gravitational attraction of the Earth.

Please put a diaper on your face until you can learn to put your words where they belong. You haven't been intellectually potty trained yet.

ETA:
And quite frankly, this argument just confirms to me your intellectual dishonesty and lack of integrity. Everything I posted were the first-page google hits for the search "orbit free fall" in .edu and .gov domains. You had to look over masses of good information to cherry-pick the source you posted.

 

[Terry]

Free fall is a specific term for falling into a gravity well. The difference between that sort of Ws and the others, is you are accelerating the entire time. In water, in orbit, in outer space, you are not accelerating, but there is no gravity. Zero-G

Are you still saying that something in an idealised (circular, non-decaying, perfect vacuum) orbit is not accelerating? You keep using that word, but I do not think it means what you think it means... something moving in a circular path has a continuously varying velocity vector. Acceleration is the rate of change of velocity. How can something moving in a circle not be accelerating?

 

[The Man]

Nonsense. I'm trying to clear the mess you and a couple of others are making. Like this:


Free fall has a specific meaning, and it is not what the ISS is doing. It is in orbit. It would be just as wrong to say the moon is in free fall. Nonsense talk. .

The moon is in free fall, an orbit is just freefall with sufficient tangential velocity.
Understand the principles and stop dumping terminology.

Nope. You just confused things even more. And you are adding to the "force" problem. According to GR there is no force. It is warped spacetime, not a force..

Which can be measured as a force in certain reference frames, unless you claim you are always weightless because of GR, understand the principles and stop dumping terminology.

But to the MM mess, everything is influenced by gravity, all the time. The ISS is weightless, the astronauts are weightless, if you attach a scale to anything in orbit, there is no force of gravity, no weight. This is the prime confusion here. You are looking at gravity like a magnetic field or something.

It doesn't work like that at all. The ISS is influenced by the sun and moon and Jupiter as well, but the gravity of all those bodies doesn't matter (except for really small tidal forces). Nobody weighs anything onboard. It is Wss, they are Ws.

No you mess everything up by relining on terminology and not even attempting to understand the concepts that terminology is based on

You could say the same thing if they look at the sun. It is influencing them as well. But they are weightless. If they were twice the distance from the earth as the moon, either in orbit, or not, they would still be weightless. Zero-G.

This is why I said there are some major misunderstandings about gravity going on in this thread. You can blast off so you are not even in orbit around the earth anymore, and you are still in orbit around the sun. But you don't feel anything, much less consider your ship in free fall.

Actually everything in orbit around the sun is in freefall towards the sun, understand the principles and stop dumping terminology.

You are now in orbit around the sun. Blast off away from the sun (Voyager), and now you are in orbit around the center of the galaxy. Still the exact same situation onboard. If you are not accelerating, no gravity.

If you go with the nonsense being spouted here, you would say Voyager isn't really in zero-G, it is in free fall around the center of the Milky Way! It is accelerating because it is in orbit around the Galactic center!

Hey, you might finally be getting the concept.

Stop pinching.

Not until you wake up.

 

[lenny]

But standing on that sphere you are not orbiting that sphere are you?

no. but i thought i met your definition of weightless, and we agree i would not be weightless in that case.

 

[lenny]

How can something moving in a circle not be accelerating?

it cannot.

But how might something accelerating in a circle be weightless?

 

[Terry]

it cannot.

Robinson apparently says it can. Unless I'm misunderstanding him.

 

[lenny]

Robinson apparently says it can. Unless I'm misunderstanding him.

methinks you are right on this one. (i know it is pretty basic physics, but for some reason i felt like agreeing with you.)

 

[Paul]

Gravity escapes the event horizon. So gravity is not effected by gravity. Or warped spacetime. Gravity IS warped spacetime.

But what about the magnetic field? Which we theorize is due to virtual photons. Does the magnetic field of our spinning massive singularity not escape the event horizon?

At which point we run smack in to the mental wall.

http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/black_gravity.html

 

[robinson]

acceleration
1. The rate of change of velocity.
2. The act or process of accelerating, or the state of being accelerated. Negative acceleration is called deceleration .

velocity (symbol V )
1. = speed. See note.
2. A vector quantity equal to speed in a given direction.

speed
Rate of motion.
Rate of motion in a straight line is called linear speed, whereas change of direction per unit time is called angular speed. Speed and velocity are often used interchangeably although some authorities maintain that velocity should be used only for the vector quantity.

vector (see link)
http://roland.lerc.nasa.gov/~dglover/dictionary//v.html#vector

I you want to say the ISS is accelerating, please use a source to explain why. Same for that free fall crap.

If something is falling towards the earth it is accelerating, according to the formula for the acceleration of gravity (symbol g)
By the International Gravity Formula, g = 978.0495 [1 + 0.0052892 sin2(p) - 0.0000073 sin2 (2p)] centimeters per second squared at sea level at latitude p.

Things that are indeed free falling are accelerating the entire time. The ISS is not, any more than the moon is.

If you just consider the ISS, or any other body, in an orbit like the moons, you can see how ridiculous the concept is. An orbit is not the same as free fall. No matter how many web sites say it is.

It is very common misperception.

 

[Terry]

jeebus. Read a physics book, for ed sake.

Acceleration is *defined* as the rate of change of the velocity vector.

ETA: here's a lecture from MIT's introductory physics course that goes into this:

http://ocw.mit.edu/NR/rdonlyres/Phy...F69-58D4-4853-9B2A-352823E2CA6A/0/binder5.pdf

 

[Olowkow]

TheMan:

. Although the astronauts in the ISS can not directly feel this weight or the force of gravity (from the earth), the fact that they can just look out a window and see that they are orbiting and not traveling in a “straight” trajectory tells them that they are under the influence of a gravitational field. Someone else also mention time dilation but that requires precise clock and communication, looking out the window is about the simplest experiment there is.

When talking of experiments to distinguish acceleration from gravitation it is common practice that it is taken for granted that there is no communication from a "local frame" to the outside world. Looking out the window requires communication via photons. Even a beam of light in an accelerating "elevator" in space which horizontally crosses the room will appear to be deflected "downwards".
The question remains, how does one distinguish experimentally between being in orbit and simply traveling in a so called "straight line" in space, where weightlessness is concerned?

 

[Hellbound]

Did you even graduate high school, robinson? This is 9th grade Earth Science material here.

acceleration
1. The rate of change of velocity.

velocity (symbol V )
1. = speed. See note.
2. A vector quantity equal to speed in a given direction.

Definition 2 is accurate. Velocity is a vector quantity. That means it is, specifically, speed in a particular direction. Here's the important bit:

If you change the direction of motion, you change the velocity. Even if you want to use velocity as a synonym of sped, you still MUST have an acceler5ation, or a net force, in order for the direction of motion to change. An orbit has a constantly changing direction of motion, thus is is accelerating due to gravity...i.e.-free fall.

 

[Terry]

The question remains, how does one distinguish experimentally between being in orbit and simply traveling in a so called "straight line" in space, where weightlessness is concerned?

Take a very long thin object, and see if there appears to be a torque on it. If not, try it at 90 degrees, just in case you had it accidentally aligned the first time.

 

[Hellbound]

You could also arrange a laser aimed at a target, both affixed to a rigid frame, and the frame mounted on a device that allowed you to rotate and elevate it. If I'm thinkgin correctly, the point on which the laser beam hits the target should change depending on the angle of the beam (if in orbit). I think that's the case, but if not I'm sure one of the actually intellgient people here who deal with physics every day can correct me

 

[Paul]

free fall A state in which a body is falling freely under the influence of gravity. In orbit, astronauts and spacecraft are still held by gravity and are in fact falling freely toward the Earth. However, because of their speed (orbital velocity), the amount they fall just equals the amount the Earth's surface curves away, and the effect is apparent weightlessness. (emphasis mine)

"free fall" A Dictionary of Space Exploration. Ed. E. Julius Dasch. Oxford University Press 2005. Oxford Reference Online. Oxford University Press. Lincolnshire Library Service. 5 July 2008 <http://www.oxfordreference.com/views/ENTRY.html?subview=Main&entry=t212.e704>

 

[lenny]

jeebus. Read a physics book, for ed sake.

Acceleration is *defined* as the rate of change of the velocity vector.

hi robinson,

i don't think you even need a new book: Terry's conclusion follows from the material you posted

acceleration
1. The rate of change of velocity.

velocity
2. A vector quantity equal to speed in a given direction.

motion in a circle implies a change in the direction of velocity.
changing the direction of a vector implies it has a nonzero rate of change.
a nonzero rate-of-change of velocity implies acceleration

thus motion in a circle implies acceleration.

(from your own posted definitions).

what about this feels wrong to you?