Science Forums

# Gravity

## Recommended Posts

Tormod

I agree that there is no evidence that gravity changes over time, however relativistic speeds are another matter.

If you drop an object in earths gravitational field it accelerates at 9.8m/s*2. True, but this is a non-relativistic example. However, even on earth its not difficult to create a relativistic example.

For an object travelling towards us at relativistic speed, there are 2 possible points of view. The view of an observer on the surface of the earth, and the view of an observer on object. They will observe different accelerations because the object is time dilated by velocity.

Take an object travelling at 0.98mm less than the speed of light. If it was accelerated at 9.8m/s*2 from the view point of our observer on earth, it would reach the speed of light in 0.1ms, after dropping about 30km. At that point it would of course have infinite mass and energy. Clearly that doesn't happen, so we have to take the point of view from an observer on the object. He gets more time dilated the closer he gets to the speed of light, so he never reaches it. In short, to get the acceleration from the point of view of an observer standing on earth = (9.8m/s*2)/(time dilation due to relative velocity of object towards earth). Gravity will accelerate the object in just the same way as any other force. It is not the acceleration that is constant, but the energy gain. It MUST be the energy gain. Any other result will break the conservation of mass/energy rule, and in normal space. A lump of mass/energy travelling down, say, 1 meter will gain the same amount of energy, regardless of its velocity. To find out how much the velocity has increased for that energy gain, you need to apply the lorentz transform.

As evidence of this conclusion, I submit our continued existence. There are cosmic rays of sufficient velocity to be accelerated to the speed of light by the suns gravitational field, if gravitational acceleration was truly independent of velocity, and yet the sun has not been destroy by a cosmic ray of infinite mass.

We get other, less easily solved, problems when dealing with massive gravitational fields. Take the case of a massive planet with a gravitational time dilation factor of 2 at the surface. On the surface our observer sets up an experiment. He measure the acceleration of a ball on a horizontal frictionless surface towards a 1kg mass. meanwhile an observer peering through a telescope from a spaceship at zero relative velocity, but (mostly) outside the gravitational field of the planet. Because he is not (much) suffering from the same gravitational time dilation, he sees the ball accelerating at 1/2 the speed of the observer on the ground. He measure the mass as 1/2 that of the observer on the ground. Which, one will conclude that the mass is 1kg? Further thinking will lead to the conclusion that escape velocity is dependent on observer too.

Freethinker

I am NOT asserting that basic laws and metrics WERE different. I am asserting that they COULD be. The evidence is for very different galaxies at that time so you can't use observation to prove that the basic laws were the same, unless you can convincingly show that the galaxies then were exactly what we would expect. Right now, that is not the case. The forms of early galaxies clearly came as a surprise.

The burden of proof is not mine. If anybody's, it is yours. It was you who said:

"As we are able to see galaxies billions of light years away, we are actually seeing how things were billions of years ago. If gravity was different at that point in time, what we observe would require different understandings of gravity's parameters in order to correlate what is going on.

But this does not appear to be the case,

Thus gravity seems to have held relatively constant."

• Replies 104
• Created

#### Popular Days

Originally posted by: BlameTheEx

As evidence of this conclusion, I submit our continued existence. There are cosmic rays of sufficient velocity to be accelerated to the speed of light by the suns gravitational field, if gravitational acceleration was truly independent of velocity, and yet the sun has not been destroy by a cosmic ray of infinite mass.

I don't understand this example. Yes, this is obviously something that does not happen, but I fail to see how that has any impact on my claim that physical mass is not relevant for the cosmic constant of gravity.

Gravity affects an object and thus the mass it has is relative to the force affecting it (like pressure gives us the density of air at surface level). But it is not the other way around - a heavy object does not change the force of gravity.

9.8m/s^2 is obviously local...decided by the mass of Earth. On the moon this rate is different. But that is because the gravitational constant is...constant.

Am I way off here? I admit to not being a physicist!

##### Share on other sites

Tormod

Well, doubtless the gravitational constant is constant. The problem is in how gravity works in relativistic conditions. Regardless, I am sure it works in a constant manner. It is just open to debate what that constant manner is!

As I showed you with the second example, there can be debate as to the nature of gravity when gravitational time dilation becomes significant. My guess is that the gravity remains a constant for our 1kg mass when observed locally, but appears as a 1/2kg Mass when viewed from the spaceship, so for outside observers a very very heavy object (the planet) DOES change the force of gravity, sort of. I say "sort of" because a 1/2kg mass dropped from the spaceship will have 1kg of mass/energy by the time it hits the planet. Half of that energy is in velocity, but in principle that energy could be turned into matter to leave 1kg of matter on the surface.Perhaps you could say that 1/2kg of matter in space has the same value as 1kg on the planet. The planet will be created out of as much original mass/energy as expected from its gravitation field as measured from a distance. Still, the interesting thing is that it will have something like twice as many atoms as expected!*

From the spaceships point of view the dropped 1/2kg mass does not gain mass/energy. What happens is that the 1/2kg weight looses effective mass due to time dilation, and gains mass/energy due to velocity. The two effects are in balance. This is just what happens with any other force. Energy is gained in one manner because it is lost in another.

*A bit less than twice. I think you would have to imagine that the planet was constructed from layers, and integrate the result. I leave that calculation for somebody who didn't sleep through maths classes.

##### Share on other sites

Originally posted by: BlameTheEx

Freethinker

I am NOT asserting that basic laws and metrics WERE different. I am asserting that they COULD be.

Yes well anything "COULD be". (His caps not mine, lol, inside joke sorry) But when someone makes the assertion of a "COULD be", it should be held up to the same requirement for evidence. It might be accepted that a "COULD be" may not have as much evidence or be as well fleshed out, but that process needs to be started and followed regardless lest we spend too much time chasing obvious dead ends.

The evidence is for very different galaxies at that time

Based on the article, in SHAPE (MY caps) only. And of course first-generation star composition. We knew and expected the later.

so you can't use observation to prove that the basic laws were the same, unless you can convincingly show that the galaxies then were exactly what we would expect. Right now, that is not the case. The forms of early galaxies clearly came as a surprise.

If by "forms" you mean SHAPES, then the article supports your claim. But I have not seen anything that indicates any "surprises" in physical laws. Just in observed results. That galaxies could be formed in shapes less symetric than expected.

The burden of proof is not mine. If anybody's, it is yours. It was you who said:

"As we are able to see galaxies billions of light years away, we are actually seeing how things were billions of years ago. If gravity was different at that point in time, what we observe would require different understandings of gravity's parameters in order to correlate what is going on.

But this does not appear to be the case,

Thus gravity seems to have held relatively constant."

Again, there was nothing in the data that suggests differences in the basic laws, just in the results of their implementation. That things were less structured early on. And that galaxies formed sooner than expected. But these two would correlate and support each other.

What they seem to be required in terms of new thinking, is how easily and quickly things progressed. Not HOW they progressed.

##### Share on other sites

Freethinker

"Yes well anything "COULD be". (His caps not mine, lol, inside joke sorry) But when someone makes the assertion of a "COULD be", it should be held up to the same requirement for evidence. It might be accepted that a "COULD be" may not have as much evidence or be as well fleshed out, but that process needs to be started and followed regardless lest we spend too much time chasing obvious dead ends."

Er. I think that's just about what I have been saying all along. We don't know because we don't have useful data to ether prove or disprove the idea. Like I said at the beginning, the jury is out.

##### Share on other sites

Originally posted by: BlameTheEx

Er. I think that's just about what I have been saying all along. We don't know because we don't have useful data to ether prove or disprove the idea. Like I said at the beginning, the jury is out.

What you "have been saying all along" is that Gravity is NOT a constant. And your proofs keep being what COULD have happened in areas that we don't have any reasonto assume they happened other than the way we woould expect them to with Gravity AS a constant. For this the only thing we are given by you is a site that discusses the SHAPE of earliest galaxies.

As I slowly bring you to forced agreement on this point, you want to claim you've agreed all along. But that your OTHER original unsupported claim COULD still be true because "the jury is out".

OK. Gravity COULD have originally been little gnomes pushing down on gas particles. We have not proved it wasn't. The strange shape of the earliest galaxies might have been caused by their artistic efforts. The jury is still out!

Hey I said "could"!

##### Share on other sites

Freethinker

My position here has not budged one inch from my first post on this topic, but it has taken a long time for you to work it out. <sigh>. If separating "We have reasonable evidence for this answer" from "There is no useful evidence to make a decision" is too fine a distinction for you it would be best you ignore my posts, and leave the thread clean for those who might take an interest. Most of my posts are of that sort of nature, but you never seem to notice the qualifying words.

As for gnomes, they could indeed have been the cause, but have you ever heard of occam's razor? And before you throw occam's razor back at me, a force following a curve relative to time is not significantly more complex than a constant one.

##### Share on other sites

Originally posted by: BlameTheEx

Freethinker

My position here has not budged one inch from my first post on this topic, but it has taken a long time for you to work it out. <sigh>. If separating "We have reasonable evidence for this answer" from "There is no useful evidence to make a decision" is too fine a distinction for you it would be best you ignore my posts,

I'm glad you are finally admitting that you see no difference between making arbitrary random claims that you won't even bother trying supporting with facts ("There is no useful evidence to make a decision") and and those of us that try to stick with valid supportable scientific concepts and theories (""We have reasonable evidence for this answer"").

and leave the thread clean for those who might take an interest. Most of my posts are of that sort of nature, but you never seem to notice the qualifying words.

When you start including "qualifying words" like "There is no useful evidence to make a decision for my post" in your posts when you are making your arbitrary random claims, we ALL can discern those meaningless ramblings from intellectually honest and scientifically valid ones that ""We have reasonable evidence for this answer"" for. We all can watch your posts for honest mention of this idfferentiation.

As for gnomes, they could indeed have been the cause, but have you ever heard of occam's razor?

Ya, I use it the same way to remove the ignorant addition of a god in explanations for the same reason.

##### Share on other sites

Freethinker.

Arbitrary ramblings?

You posted:

"As we are able to see galaxies billions of light years away, we are actually seeing how things were billions of years ago. If gravity was different at that point in time, what we observe would require different understandings of gravity's parameters in order to correlate what is going on.

But this does not appear to be the case,

Thus gravity seems to have held relatively constant."

Up to this point I have tried not to rub your nose in it, but this was YOUR misinformation which i was correcting. Those distant galaxies show nothing of the kind. If it is arbitrary ramblings to correct your mistakes, then I am guilty. Now that I think of it, "arbitary ramblings" is not that harsh, although "casting pearls before swine" is more acurate.

PS I said "There is no useful evidence to make a decision" not "There is no useful evidence to make a decision for my post". Actually though, that is a reasonable addition. The post I was referring to WAS yours. You posted an assertion without useful evidence.

##### Share on other sites

I'm trying to ignore your attacks and red herrings and stick with specific topic discussions.

Originally posted by: BlameTheEx

You posted:

"As we are able to see galaxies billions of light years away, we are actually seeing how things were billions of years ago. If gravity was different at that point in time, what we observe would require different understandings of gravity's parameters in order to correlate what is going on.

But this does not appear to be the case,

OK, I stated that

1) we can see galaxies that appear to be over +10 billion light years away

2) to the best of our knowledge therefore what we now see from these galaxies happened +10 billion years ago

3) If gravity was different at that point in time, what we observe would require different understandings of gravity's parameters in order to correlate what is going on.

4) what we observe in these galaxies is consistant with what we have established for gravity and speed of light as well as other "physical constants".

which supports what I have been saying all along

Originally posted by: Freethinker

Thus gravity seems to have held relatively constant."

But this does not appear to be the case,

Please provide FACTUAL proof to support this claim.

The SHAPES of these galaxies or how early they formed, is NOT proofs. Neither of these issues supports claims of differences in gravity nor "C".

##### Share on other sites

Freethinker

Sigh. I do try. Your point 4 is effectively meaningless. Those galaxies are so different, and so unexpected that they are consistent with just about anything. They are different from what we have now, and what we expected then.

There are plenty of possibilities for these unexpected observations, but differences to "physical constants" can't be ruled out. Thus, while support is slight, it goes against constant gravity or C.

Whenever ANY observation goes against prediction, ALL theories on which that prediction is based loose support, until the explanation is found. It can be argued that the loss of support is insignificant, or the observation inaccurate, but they certainly can't profit from the observation.

Regarding "But this does not appear to be the case". That is not my reply. It is still part of the quote, which is why the quotation marks don't end till after it. I guess turn around is fair, so, as you say, please provide FACTUAL proof to support this claim.

##### Share on other sites

Originally posted by: BlameTheEx

Freethinker

Sigh. I do try. Your point 4 is effectively meaningless. Those galaxies are so different, and so unexpected that they are consistent with just about anything. They are different from what we have now, and what we expected then.

Ah yes, we are back to your "proof by repetition.".

We have gone around on this many times. You keep claiming that the SHAPES and age, which are the ONLY THINGS the article addresses, PROVES some complete lack of understanding of their operational conditions.

Yet every time we ask you provide ANY proof beyond that, you wander off on tangents, ignore the request and then start repeating the same unsupported claim again!

There are plenty of possibilities for these unexpected observations, but differences to "physical constants" can't be ruled out. Thus, while support is slight, it goes against constant gravity or C.

Evidently only in YOUR mind, as you have never been able to provide the first outside support.

PROVE IT!

and not just by repeating it over and over.

Whenever ANY observation goes against prediction, ALL theories on which that prediction is based loose support, until the explanation is found.

I see, so the entire explanation we have in ALL areas of physics have lost ALL support! Special, General relativity, QM, Particles, waves, strong and weak forces, ... out the window!

And all merely because you keep repeating it to be so!

I'm sure Hawkins can barely wait for your informing us all how it works now!. How it works now. How it works now.

I guess turn around is fair, so, as you say, please provide FACTUAL proof to support this claim.

Turn around will be "fair" as soon as you can actually provide the first support for your repetitive ramblings and your repetitive ramblings, AFTER your repetitive ramblings are proven.

##### Share on other sites

Freethinker

Freethinker

It is you that made the assertion, so stop trying to shift the burden of proof. Come to think of it, stop trying to shift the assertion. I await YOUR proof. Until then this conversation is on hold. That is, I will not bother to reply further. And will Hawkins wait for your proof? Frankly I hope he doesn't hold his breath. I certainly ain't going to.

##### Share on other sites

We see once more how Blame works. How he tries to VBlame others for his lack of factual support. Here he is now trying to drag the specific request for FACTS away from his failure to be able to do so. Instead accusing ME of it.

What we find by reviewing this thread is that this IS Blame's MO.

Originally posted by: BlameTheEx

Freethinker

It is you that made the assertion, so stop trying to shift the burden of proof. Come to think of it, stop trying to shift the assertion. I await YOUR proof. Until then this conversation is on hold. That is, I will not bother to reply further. And will Hawkins wait for your proof? Frankly I hope he doesn't hold his breath. I certainly ain't going to.

The following is some quotes from Blame's discussions with another poster here. Notice the MO. Blame makes claims which he fails to support with FACTS. When the other poster tries to get FACTS from Blame, blame shifts the subject, changes stances, ... but NEVER gets around to actually showing facts for his claims. In this first quote, the other poster is stating his frustrations in Blame's claims of changes to speed of light (thus showing was Blame that first made the claim, NOT ME) and not being able to get Blame to deal factually with it.

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.

Followed by Blame CLAIMING to have supplied proof, but not doing so

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.

With another attempt to get Blame to either accept his failure or provide proof other than repetition.

BlameTheEx: Why should it be different for gravity?

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

Notice once more it is Blame that started and keeps trying to claim gravity is different. And no matter how often asked nor by whom or how many, we get NOTHING!

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.

What is particulrly ironic in this next one is that as the frustration level of the other poster increases because of Blames constant lack of supporting his own claims no matter how often asked, that the other poster also comments on the awards Blame would receive if his claims had ANY proof.

BlameTheEx: you say: "And we know from Einstein's principle of equivalence that acceleration and gravity are indistinguishable"

Er yes. with the caveats that Einstein may yet be proved wrong,

Er, why not just chuck all of science out then? Wait a minute, you are already half there! You want to dismiss the

##### Share on other sites

MODERATOR WARNING:

This circular arguing is dumbing down the whole site, let's put an end to it. I've read through as much of the Blame/FT argument as I could stand and can't make heads or tails out of any of it. Let's start fresh.

Blame, would you please(this is a requirement) state your position in as clear a way as possible?

Freethinker, would you please respond only to the post that I have just asked Blame for?(also a requirement)

If you are unable to do this simple task I will have no choice but to lock the thread. We are all above this pettiness, so let us get on with an intelligent discussion.

Keep in mind that no one particular individual is being blamed for this, I just want it to end.

Thank you both for your cooperation, it is appreciated.

##### Share on other sites

Uncle.

For you anything.

Ok, its simple.

I refuted Freethinker's claim of 09/27/2004 05:52 PM. I think he said the same thing, rather more clearly in his post of 10/07/2004 12:31 PM here:

__________________________________________________________

1) we can see galaxies that appear to be over +10 billion light years away

2) to the best of our knowledge therefore what we now see from these galaxies happened +10 billion years ago

3) If gravity was different at that point in time, what we observe would require different understandings of gravity's parameters in order to correlate what is going on.

4) what we observe in these galaxies is consistant with what we have established for gravity and speed of light as well as other "physical constants".

which supports what I have been saying all along

_______________________________________________________________________

Gravity may well be a constant, but the observations from the most distant observed galaxies can't be used to justify the idea. They are too different and the differences too unexpected to justify anything much. To use them in justification, you would have to show that the differences are what we would expect if gravity was constant, or at a minimum that the differences were not caused by a change in gravity.

For evidence I give:

"The final ACS image, assembled by Anton Koekemoer of the Space Telescope Science Institute, is studded with a wide range of galaxies of various sizes, shapes, and colors. In vibrant contrast to the image's rich harvest of classic spiral and elliptical galaxies, there is a zoo of oddball galaxies littering the field. Some look like toothpicks; others like links on a bracelet. A few appear to be interacting. Their strange shapes are a far cry from the majestic spiral and elliptical galaxies we see today. These oddball galaxies chronicle a period when the universe was more chaotic. Order and structure were just beginning to emerge."

##### Share on other sites

Originally posted by: BlameTheEx

I refuted Freethinker's claim of 09/27/2004 05:52 PM.

First, you were specifically told to stick to restating your claims. NOT to attacking me again. You have yet to REFUTE anything. And here we see that you are back to the same thing again.

I think he said the same thing, rather more clearly in his post of 10/07/2004 12:31 PM here:

Yes I tried to make it as clear and simple as I could so no one would have trouble understanding it.

(clipped a restating of my position)

which supports what I have been saying all along

No it doesn't and we will explore why.

Gravity may well be a constant,

Which conflicts with your original assertion. Glad you have changed your tune and now agree with what I originally stated.

but the observations from the most distant observed galaxies can't be used to justify the idea.

And here we are back to square one. So I need to ask the same question again.

What about the old/ distant galaxies indicates ANY change in Gravity?

Here we go again. You acknowledge that there is nothing to suggest that gravity is NOT a constant. Then you start to suggest otherwise.

They are too different and the differences too unexpected to justify anything much.

Again, this is NOT proof. This is a statement of personal opinion on your part and that is all.

To use them in justification, you would have to show that the differences are what we would expect if gravity was constant, or at a minimum that the differences were not caused by a change in gravity.

Until we have ANY reason to question the universal (as in Universe) constant of Gravity, ah, well, we have no reason to question Gravity. We DO NOT have to show that gravity has not changed in order to assume that gravity has not changed if nothing we see suggests that there has been "a change in gravity"

For evidence I give:

"The final ACS image, assembled by Anton Koekemoer of the Space Telescope Science Institute, is studded with a wide range of galaxies of various sizes, shapes, and colors. In vibrant contrast to the image's rich harvest of classic spiral and elliptical galaxies, there is a zoo of oddball galaxies littering the field. Some look like toothpicks; others like links on a bracelet. A few appear to be interacting. Their strange shapes are a far cry from the majestic spiral and elliptical galaxies we see today. These oddball galaxies chronicle a period when the universe was more chaotic. Order and structure were just beginning to emerge."

The word gravity does not even appear in your suppose PROOF. Yet you pretend this is some kind of proof to support "a change in gravity"! If this PROOF addresses Gravity, why did they completely fail to even MENTION it?

In fact they give specific OTHER reasons for the differences

"These oddball galaxies chronicle a period when the universe was more chaotic. Order and structure were just beginning to emerge."

So let's see if we can bring this to a specifically defined end.

1) Do you agree that there is nothing to support a claim that gravity is not a constant over time?

2) if not, what PROOF do you have? (That actually talks about Gravity specifically and is not just your personal opinion)

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.