[Freethinker]

You say it much better than I Irish, thanks.

And yes I can when I want to, thanks.

You should see what I WAS going to post! :-)

[IrishEyes]

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You say it much better than I Irish, thanks.

And yes I can when I want to, thanks.

You should see what I WAS going to post! :-)

Oh FreeT, I wrote your other reply myself, then remembered that we are both supposed to be setting an example, so i decided to beat you to the punch!

As for saying ANYTHING better - HAHAHAHA ! That's just a laugh! You are more eloquent than Henry David, when you want to be. And from me, that's a MAJOR compliment!

[TeleMad]

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TeleMad: Let’s start by looking at an orbiting laboratory such as the International Space Station. If an astronaut gives something a small push it moves off in a straight line at constant speed obeying Newton’s first law of motion. In fact, it does so much better than here on Earth where friction with a surface or air resistance quickly causes it’s motion to stop.

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FreeThinker: The ISS has an atmosphere somewhat similar to Earth's in order for the inhabitants to live without self contained suits. Therefore the "air resistance" in the ISS would be reasonably similar to here on earth and contrary to this post WOULD exhibit a similar effect on the motion of an object in it.

Yep, I goofed in the details (but the point I was making is still valid).

The real difference is that in the IIS the object would be moving in a straight line at 'constant' speed through "air", while on Earth it couldn't do that. On Earth one would have to slide the object across some surface to make it go in a straight line* at which point friction would prevent the relative motion between the two and bring the object to a quick halt.

*Pushing an object horizontally through the air near the surface of the Earth produces semi-parabolic, projectile motion, because of the dowanward accleration gravity produces: so trying such wouldn't produce straight-line motion. One could produce straightline motion in air by just dropping the object, but then its velocity would change, again do to gravity.

[TeleMad]

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BlameTheEx: Potential energy has to be stored somehow. Worse our object falling into a gravitational field has GAINED energy. To balance the books you have to consider the storage of negative energy, or to put it another way you have to look for an already existing supply of energy that can be tapped. You can't just assume that it happens. There has to be a mechanism.

There is. Again, think about the process in reverse. If the object is already on the surface of the Earth (or other massive object), what must be done to send it out into space? A huge input of energy is needed to overcome gravity. Now if we play that scenario in reverse, where the object is already in space and falls to the surface, then there will be a huge release of energy...there must be. So an object in space gravitationally attracted to the Earth has potential energy: it just needs to fall closer to the Earth in order to convert that potential energy into kinetic energy.

I had mentioned that the explanation could also be done using the concept of binding energy. Here’s the definitive definition of gravitational binding energy on the net.

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Gravitational binding energy
The gravitational binding energy of an object is the amount of energy required to accelerate every component of that object to the escape velocity of every other component. It is also the amount of energy that is liberated (usually in the form of heat) during the accretion of such an object from material falling from infinity.

For a spherical mass of uniform density, the gravitational binding energy is

U = [(3/5)GM^2]/r

Where G is the gravitational constant, M is the mass of the sphere, and r is the radius of the sphere.

Assuming that Earth is uniform (which is not correct, but is close enough to get an order-of-magnitude estimate) with M = 5.97×10^24kg and r = 6.37×10^6m, U is 2.24×10^32J. This is roughly equal to one week of the Sun's total energy output.

According to the Virial theorem, the gravitational binding energy of a star is -2 times its internal thermal energy.” (http://en.wikipedia....binding_energy)

A bound system is at a lower energy level than its constituent parts. It takes an input of energy to unbind the constituents; on the other hand, converting constituents from the free state to the bound state releases energy (note that the quote states that if the Earth’s constituents were all free and then accreted to reform the Earth, the amount of energy that would liberated would be equal to one week of the Sun’s total energy output!)

[Freethinker]

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Originally posted by: TeleMad
Yep, I goofed in the details (but the point I was making is still valid).

Still a qualifier in there, but I'm glad to see you can admit error. Perhaps we can have some good posts together.

[BlameTheEx]

Telemad

"So an object in space gravitationally attracted to the Earth has potential energy: it just needs to fall closer to the Earth in order to convert that potential energy into kinetic energy"

Just so. However The object doesn't just have the potential energy of a fall to earth. It can potentially fall into ANY gravitational field. The potential energy available MUST approach that of its entire mass/energy, as such gravitational fields are known to exist. This potential energy is there regardless of whether it goes anywhere near any gravitational field (unless you care to propose that it knows its future, or can gain potential energy at some point). If this potential energy is not in fact its own mass/energy then I am at a loss to figure out where you propose it is stored. Are you proposing a store of energy, equivalent to the objects mass, attached to it, but undetectable? Potential energy does not just exist. It has to be somewhere.

The force that we have most understanding of, the electromagnetic, follows this rule. An electron releases energy when approaches an unpaired proton. This is also the basis of chemistry (OK, I am simplifying a bit here). However this potential energy IS got from somewhere known. The combined mass of proton and electron drops.

We know less about the forces that bind an atom together, but the same applies. When protons and neutrons bind together energy is released, but this energy is identical to the energy of (mass of the separate neutrons and protons) - (mass of resulting atom).

We may not understand all about electromagnetic and atomic binding forces, but we can weigh the particles concerned accurately. We have plenty of good evidence that the energy released is equal to mass/energy lost. This is why the principle of conservation of mass/energy is so widely respected. Why should it be different for gravity?

Regarding this concept of gravitational binding energy. All it really says is that once a gravitational body is created, it takes energy to separate its constituents again. True enough. The energy releases in its creation has to be returned. But energy is just mass/energy. This is just another way of saying what I have been saying. Energy was liberated in the creation of the body, AND THAT MEANS IT LOST MASS. As the energy was lost as heat, and the quantity of matter remained constant we must conclude that the mass energy of matter in a gravitational field is less that it was outside. But this is a separate issue from that of further objects falling onto the body. Those objects have there own mass/energy to loose.

[Tormod]

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Originally posted by: BlameTheEx
Sorry.... seem to have created a duplicate of last message. I can't seem to remove it completly so I have replaced it with this message. Any chance of adding a delete button to the options?

No, sorry - the option to remove posts is not available since it could render debates useless if someone accidentally (or intentionally) deleted their posts in a thread. So just do as above - usually we just write "*sorry - double post*" (if applicable) or "*post deleted by myself*" or someting. No big deal.

Tormod

[Freethinker]

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Originally posted by: Tormod

Tormod

HE'S BACK!

Welcome back.

[TeleMad]

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BlameTheEx: Regarding this concept of gravitational binding energy. All it really says is that once a gravitational body is created, it takes energy to separate its constituents again. True enough. The energy releases in its creation has to be returned. But energy is just mass/energy. This is just another way of saying what I have been saying.

No it's not...not at all. I'll finish the relevant part of your quote before explaining...

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BlameThEx: Energy was liberated in the creation of the body, AND THAT MEANS IT LOST MASS. As the energy was lost as heat, and the quantity of matter remained constant we must conclude that the mass energy of matter in a gravitational field is less that it was outside. .

Do you see any mention of the speed of light having to be reduced in anything you just stated? Nope. Yet here is what you said that I have been countering...

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BlameTheEx: So how does it work out? An object falling into a gravitational field gains energy as velocity. This kinetic energy is balanced by a loss of energy from its mass. That is calculated as E=MC2. The C is the speed of light. Inside a gravitational field C is lowered.

The best way to think of gravity is that mass/energy reduces the speed of light. The formula for this reduction is clear enough, in non-relativistic situations, but it would be brave to extrapolate it further without evidence.

Remember all my comments about "no need to monkey around with the speed of light" to account for the changes in energy/mass?

So actually, what you just said in your last post is what I have been saying...and it contradicts what you said.

You can't have your cake and eat it too. Pick a position.

[TeleMad]

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BlameTheEx: Potential energy has to be stored somehow.

Any object gravitationally attracted to Earth, but not in physical contact with the Earth, has potential energy simply from the fact that it is gravitationally attracted to Earth.

Take the moon Io: it has potential energy. We don't realize this because Io is more strongly bound, gravitationally, to other objects in our solar system. But imagine removing the Sun, Jupiter, Saturn, etc. - leaving only the Earth and Io. What would happen? Io would fall in towards the Earth (and vice versa, to a lesser degree) converting gravitational potential energy into kinetic energy.

The potential energy is there...an object does not have to be physically hoisted away from the Earth's surface in order to store gravitational potential energy in it. THERE IS NO NEED TO MONKEY AROUND WITH THE SPEED OF LIGHT.

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BlameTheEx: Worse our object falling into a gravitational field has GAINED energy.

You mean because it converted some of its gravitational potential energy into kinetic energy? Yep, just as I've been saying.

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BlameTheEx: To balance the books you have to consider the storage of negative energy, or to put it another way you have to look for an already existing supply of energy that can be tapped.

Yeah, the gravitational potential energy I keep telling you about.

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BlameTheEx: You can't just assume that it happens. There has to be a mechanism.

Which I've explained, and, unlike you, in a manner that doesn't require breaking any law of physics.

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BlameTheEx: Right or wrong, I have given a plausible mechanism.

No, you haven't. Your mechanism violates the special theory of relativity. That's not a plausible mechanism.

[TeleMad]

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BlameTheEx: The force that we have most understanding of, the electromagnetic, follows this rule. An electron releases energy when approaches an unpaired proton. This is also the basis of chemistry (OK, I am simplifying a bit here). However this potential energy IS got from somewhere known. The combined mass of proton and electron drops.

And when a free proton and a free electron bind, gravitational binding energy is also released and contributes to the total reduction in mass.

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BlameTheEx: We know less about the forces that bind an atom together, but the same applies. When protons and neutrons bind together energy is released, but this energy is identical to the energy of (mass of the separate neutrons and protons) - (mass of resulting atom).

And when free nucleons bind, gravitational binding energy is also released and contributes to the total reduction in mass.

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BlameTheEx: We may not understand all about electromagnetic and atomic binding forces, but we can weigh the particles concerned accurately. We have plenty of good evidence that the energy released is equal to mass/energy lost. This is why the principle of conservation of mass/energy is so widely respected. Why should it be different for gravity?

Who said gravity is different? You? That's because you are confused.

Any binding that involves free objects becoming more tightly bound physically releases gravitational binding energy, resulting in a decrease in mass. It's not usually noticed because the gravitational force is terribly feeble compared to the strong and electric forces, which are about 10^40 times stronger than gravity.

Imagine you fuse a huge amount of protons and neutrons – enough to have one gram of mass converted into energy because of the strong force. You could easily measure a 1-gram difference in mass. But how would you measure the change in mass caused by gravitational binding energy? For the same experiment, that difference would be only about 0.0000000000000000000000000000000000000000001 grams.

[BlameTheEx]

Telemad


You do leave me with a lot of things to reply to. Please forgive me for limiting myself to your last statement.

"Any binding that involves free objects becoming more tightly bound physically releases gravitational binding energy, resulting in a decrease in mass. It's not usually noticed because the gravitational force is terribly feeble compared to the strong and electric forces, which are about 10^40 times stronger than gravity"

Now we are getting somewhere. We can agree on that. The mass is indeed reduced. There's no reason to suppose that any of the atoms, electrons ect disappear. However while the gravitational force is relatively weak, we are considering situations where there is enough mass to make it very strong indeed. The reduction of mass for matter on the surface of some know astronomical bodies will be a good proportion of the total. How do you feel that mass can be gone? Are you imagining that a proportion of the atoms disappear, or that the are just lighter? If some disappear, then where do they go. If they become lighter then what is the formula?

I can't imagine where the atoms would disappear to if they did, but I can tell you the formula if they get lighter. It is proportional to the time dilation! Gravitational time dilation is DEFINED that way. It is equal to the ratio of frequency of a photon from when it is emitted from the surface, and when it is received outside the gravitational field (Ok,Ok mostly outside.There is no end to a gravitational field), or the for that matter the ratio of frequency gain if the photon goes the other way. This ratio is identical to the ratio of energies for the photon, and naturally enough it's also identical to the ratio of mass/energy (including kinetic) of an object dropped to the surface. It doesn't matter how a lump of mass/energy gets to the surface. The proportional increase of mass/energy must be the same. The dropped object gains kinetic energy in exact proportion to its gravitational time dilatation. Coincidence?

[Truth]

Simplicity is the best answer. I am sorry to say, that gravity is a falling effect and everything in the universe is in actuality, falling in expansion.In other words falling and expanding in equalibrium.So any place where you have matter that is larger or greater the density the greater the falling effect. A blackhole is an extreme example of that.

[TeleMad]

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BlameTheEx: We can agree on that. The mass is indeed reduced. There's no reason to suppose that any of the atoms, electrons ect disappear.

Agreed. “Missing mass” caused by binding is not missing particles…it’s mass that has been converted into energy (via E = mc^2) and liberated from the particles that bound.

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However while the gravitational force is relatively weak, we are considering situations where there is enough mass to make it very strong indeed. The reduction of mass for matter on the surface of some know astronomical bodies will be a good proportion of the total. How do you feel that mass can be gone?

Converted to energy via E = mc^2.

Why do stars expand into red giants when the core of the star contracts? Yes, when the core contracts, the star’s size increases, dramatically. Where does the vast amount of energy needed to push all of that enormous amount of matter out millions of miles come from? From the release of gravitational potential energy as the core contracts. In the process, a huge amount of mass in converted into energy…a HUGE amount.

You still haven’t given us any valid reason to look beyond mainstream theories/laws to explain any of this – there is no need to monkey around with the speed of light, and very good reason not to do so.

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BlameTheEx: I can't imagine where the atoms would disappear to if they did, but I can tell you the formula if they get lighter. It is proportional to the time dilation! Gravitational time dilation is DEFINED that way.

I went back to Wikipedia and the equation they have for gravitational time dilation doesn’t include mass.

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”Gravitational Time Dilation.
…
Time dilation around a black hole may be described using the following equation:
To = Tf (1 – Ch/Co)^(1/2)

Where t0 is time for the object undergoing dilation, tf is time for an observer outside the system, Ch is the circumference of the event horizion, and C0 is the circumference of the object's orbit about the black hole.” (http://en.wikipedia..../Time_dilation)

So can you support your statement that gravitational time dilation is DEFINED in relation to “missing mass” being proportional to time dilation.

PS: And even if you do, you still haven’t supported the REAL issue – You still haven’t given us any valid reason to look beyond mainstream theories/laws to explain any of this – there is no need to monkey around with the speed of light, and very good reason not to do so.


2) Are you confusing time dilation – which is a direct consequence of relativity - with reduction in the speed of light – which is a direct contradiction of relativity?

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BlameTheEx: [Gravitational time dilation] is equal to the ratio of frequency of a photon from when it is emitted from the surface, and when it is received outside the gravitational field (Ok,Ok mostly outside. There is no end to a gravitational field), or the for that matter the ratio of frequency gain if the photon goes the other way. This ratio is identical to the ratio of energies for the photon, …

Okay, you’re discussing standard gravitational red shift.

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BlameTheEx: … and naturally enough it's also identical to the ratio of mass/energy (including kinetic) of an object dropped to the surface.

I assume you’ll have no problem providing support for that.

None of your post even addresses the real issue between us – you still haven’t given me, or anyone else, any valid reason to look beyond mainstream theories to explain any of this – there is no need to monkey around with the speed of light, and good reasons not to do so.

[BlameTheEx]

Telemad.

Converted into energy is indeed right. But that wasn't quite the question I was trying to put. The energy is gone, but all the atoms are still there. We now have lower energy atoms. That was the puzzle I was asking you to consider.

Your formula for Gravitational Time Dilation is based on a black hole. Like I have said before, it's hardly fair to ask me to answer an argument that STARTS from the premise that I am wrong. Like I pointed out before, I can't deny the properties of black holes, once they are formed. I just suggest that it is impossible to create them. There is probably lots of self consistent literature on fairies too.

Your link points to a blank page. Apparently Wikipedia does not have an article on the topic yet.

I will get back to you regarding about links to Gravitational red shift, but the ratio of energy between free space and the surface of a body is constant for photons, bricks, cosmic rays or what have you. It has to be. Gravitational potential energy is independent of how a lump of mass/energy is delivered to the surface. If it were not it would disobey the law of conservation of mass/energy. Think. In principle we could have a machine that converts a brick into photons, and visa versa. so we have 2 bricks. One is dropped to the surface, and the other converted to photons, beamed to the surface, and converted back to a brick+ additional energy due to the gravitational shift in the photons wavelength. If that additional energy was not the same as the kinetic energy of the first brick then its not difficult to imagine a system for creating as much energy as we wish from nowhere. Getting the brick back into free space should take exactly the same energy as was freed by dropping it, so we just use the less energy consuming process for the upward journey, the other for the way down, and repeat till all our batteries are charged.

As for monkeying with the speed of light, well I am, and I ain't. The usual answer when dealing with time dilation. Its all a matter of the observer. Local measurements will always hold C to be constant, as Einstein maintained. However for an observer looking at events on the surface from outside the gravitational field things move more slowly. As you accept that Gravitational Time Dilation happens, how can you disagree with this? A local observer on the surface of a body with a time dilation factor of 2 will measure a photon as travelling 300 Meters in a microsecond (lets avoid a few quibbles by stating that this photon is travelling parallel to the surface of the body), but the Observer looking down notes 2 microseconds have passed. He can only have one of 2 conclusion. Ether C is half what is expected, or distances on the surface are twice the local measurement. I would hold to the former, but the latter also holds fascination because it would lead to the inescapable conclusion that any singularity would have, from an external observers point of view, infinite diameter.

My apologies for not going further just now into your reply but I am tired and have rather a lot to do. Hopefully I will get back to finishing next week.