[Freethinker]

OK guys, let's try to bring this in line or we will need to ban or close the thread down. Is there some way you two can start with some fundamental aspects and work out the details? And both side use valid verifyable data to support claims. I won't point fingers, but we do expect all sides to be supported with facts here.

The most repeated items seem to be acceleration vs velocity. Gravity as an issue.

Can someone start by suggesting some defintions so we are sure we are using the terms the same? Then we can step to interactions, such as acceleration "simulating" gravity (Einstien's elevator thought experiment). Only later to bring in outside viewers as we build the discussion.

Let's build from the bottom up rather than throw the whole thing in and try to rip it down.

And in this corner...

[TeleMad]

Quote

BlameTheEx: What a berk, Ok you have this room all to yourself. What you going to do now, scream insults at the walls?

No...unlike you, the walls don't continue to argue against logic and science.

I envisioned us as playing a game of chess: a battle of wits with two opponents trying to show that his own position is superior. But you blundered from the beginning and wouldn't admit it. So I pressed on and found your king exposed. I called mate-in-1 on you and instead of your resigning, you claimed it wasn't there. So I showed you by mating you. And what did you do? You moved your king like a knight, jumping over chess pieces in the process, and then claimed you never were in mate. As I would in a chess game, at that point I knew you weren't a worthy opponent...at that point, I lost all respect for you.

[TeleMad]

We can start with this.

First, BlameTheEx seems to be confused about some of the very basic terms of motion.

1) Speed. This is a scalar quantity (has magnitude, but no direction) and is distance (another scalar quantity) divided by time.

2) Velocity. This is a vector quantity (has both magnitude and direction). Velocity and speed are not the same thing: speed is the, well, speed half of velocity (the other half being direction). So velocity can change even if speed doesn't.

3) Acceleration. This is the rate of change in velocity. Note that since velocity is a vector, then velocity can change by an object (a) changing speed (either an increase or a decrease), ( changing its direction of motion, or © changing both its speed and its direction of motion.

Now on to the relativity stuff.

Plain old special relativity tells us that the greater the difference in speed between two observers in uniform motion, the greater the degree of time dilation and length contraction.

Tangential speed is the speed of an object rotating about a fixed point, and varies with distance from the center. For example, a person pressed against the wall of the Tornado ride has a greater tangential speed than a person near the center when they each make a full turn in the same time. Tangential speed is tied to accelerated motion, since the object of interest is not moving in a straight line (even though it is moving at constant speed, in our example).

If one observer (who obviously is at rest in his own reference frame), such as a person outside the Tornado ride, sees another person moving with a large tangential speed, such as another person pressed against the inner wall by inertia, then the stationary observer will note time dilation and length contraction (in the direction of instantaneous motion) when viewing the other person’s reference frame. This is shown by logic and by the quote from Brian Greene. Note that the degree of time dilation and length contraction are calculated the same way as in special relativity, using the relativistic gamma factor.

Thus we see that this kind of constant acceleration (change in direction of motion, by rotating about a fixed point, while maintaining a constant speed) produces time dilation and length contraction (as seen by an observer not undergoing that same motion), with the degree of the difference in time and length intervals being tied to the difference in speeds, and being calculated using the same factor (the relativistic gamme factor) used in special relativity.

So we can see that time dilation and length contraction occur when:

1) Two observers in uniform motion are moving relative to one another.

OR

2) One observer, at rest, considers another observer that is undergoing constant acceleration (rotation about a point) at a constant tangential speed. This is exactly the example the Brian Greene quote used.

OR

3) Two observers are each undergoing constant acceleration (rotation about a point) at constant tangential speeds, but their tangential speeds differ.

There may be other cases, but these are enough to make the point.

Now, by Einstein’s principle of equivalence, (3) is indistinguishable from two observers experiencing different-strength gravitational fields. Thus, when one observer is “outside” a strong gravitational field while another is deep inside of it, the “outside” observer will see both time dilation and length contraction occurring in the other observer’s reference frame.

And for BlameTheEx's setup, which supposedly showed that light had slowed to 0.5c, this length contraction effectively doubles the distance the light on the surface travels, thus making a calculation for the speed of light produce c…the exact answer we are supposed to get.

PS: Another interesting quote (since it shows BlameTheEx to be wrong on something he said)…

[quote]
“… as Einstein argued eloquently

[Uncle Martin]

I am not a trained physicist, just a lay person with an interest in understanding the universe in which we exist. My hope is to learn something from these(especially this) discussions. TeleMad and Blame', could I bother you both for a bit of personal info? Would you please tell me something of your backgrounds? If I, as a lay person is to weigh two differing viewpoints, it would be helpful to know of your qualifications to make these claims. I would also ask that you resolve your current standoff, as I'm sure that many others wish to learn more from both of you. This has been a very good thread so far, let us keep it going. Thank you both for what has been posted, and hopefully for what is to come.

[TeleMad]

Here are some facts about the exchanges...

1) BlameTheEx claims that physics shows taht black holes can't form. That immediately raised a red flag for a lot of us since it goes against scientific consensus.

Note that BlameTheEx does not limit his statements ot just the singularity - he made this clear. It is a black hole - not the singularity - which he claims physics shows cannot form.

Also, BlameTheEx doesn't deny that black holes can exist. His argument already sounds like a Creationist argument. Life exists but the laws of nature show that life can't arise from non-life...therefore, God must have created life. Black holes exist but the laws of physics show that they can't be formed...therefore, God must have made them.

2) BlameTheEx claimed that the best way to think about gravity is as a slowing of the speed of light. Another reason we should all be wary of his statements since this one violates special relativity.

3) BlameTheEx claimed that if one observer were on the surface of a massive body and another observer werr out in space looking down - and the graviational time dilation made time pass twice as slowly on the surface relative to the outside observer - that either (1) the speed of light must be reduced to 1/2, or (2) the distance must be doubled, leading to black holes supposedly having infinite radii.

THIS CONCLUSION OF HIS WAS QUITE SIMPLY WRONG. Those are not the only two possiblities, and in fact, both can be dismissed without much thought. Science has the explanation, a third possiblity BlameTheEx didn't know even exised, and it "falls out" naturally from the theories of relativity. I spend a good amount of time - invested a lot of effort - into explaining that: the distance remains the same, but the "meter sticks" are reduced by half, thus effectively doubling the distance. This shoudl have ended the debate.

That should have cinched it. But then BlameTheEx tried to wiggle out by saying that the concepts I brought up applied only to special relativity, in which the observers are moving relative to each other. I then spent more time tracking down and typing out Brian Greene's explanation for why this is not so. By showing that the length contraction I discussed applied in BlameTheEx's example, I tied up all the lose end.

This SURELY should have ended the debate. Yet it didn't. BlameTheEx - in typical Creationist style - refused to listen to logic, continued to put forth ideas that violate well-supported pillars of modern science, and attempted to twist science into fitting his view. His view is right - science needs to bend to meet him.


So exactly what science is anyone here going to learn from BlameTheEx? That general relativity is wrong? That special relativity is wrong? That black holes can't form? His positions are ANTI-scientific.

[BlameTheEx]

Freethinker

Too late. As I have allready made clear. I ain't replying to people who won't be polite. Truth is I am not even reading TeleMad's replies now. Do me a favour, and let me know if he calms down and apologises. Oh, and I would also like news of flying pigs.

[Tormod]

Okay, I enjoyed this discussion for a while, TeleMad had some very decent explanations but this thread is dying now. I say let's close it and move on?

Tormod

[katesisco]

Here's something interesting. I found this today: www.AIAS.com/us Myron Evans is a Welshman who has developed a new math to accomodate his GUT which so far has led to a new kind of MRI without heavy magnets. I do not pretend to understand the math, I only read fast. It seems from the web that there are quite a few that have offered new theories but of course the test of a theory is being able to make predictions as to future discoveries and/or solutions based on your therory. The current hot topic is how our sun, Sol, interacts with our planetary magnetic field. The article in this month's NG was absolutely thrilling in as much as know so little and have so much to learn. Quite possibly a Unified Theory of Everything is just around the corner, but right now it is interesting to see the sci-fi and imagine that it is real. One site I saw with quite a bit of substantiating material, said that the interreation with the magnetic fields, of which he posed 6 for the Eath at about 30-40 degree latitudes but north and south of the Equator caused massive ejections of radioactive material from the earth's fields of energy and you do have to admit there is OKLO. I like his idea, which is based on the Gaia hypothesus, better than attributing radioactive sites to a nuclear war in the far distant past.

[wavelength?]

Does any one have any info on what causes gravity?

I know that it is caused by the curvature of spacetime around an object of mass, but why does this curvature of spacetime harness this energy and where does it come from?

[Freethinker]

It is perhaps better to think of gravity not as "caused by" the curvature, but "is" the curvature.

Think of a flat surface, like a mattress. Think of placing a golf ball on that surface, a relatively small mass. It will curve the surface some, but not much. Now put a bowling ball on the mattress. It will cause a greater deformation of the surface (spacetime). If close enough, the bowling ball's curvature will make the golf ball roll toward it because of the curvature/ gravity.

Now some big fat butt sits down...

[wavelength?]

FT, That does not answer my question. There is a force being applied to all objects of mass from (or is)the curvature of spacetime, this force must come from somewhere. It seems like all objects of mass are bubbles of matter in the medium of spacetime. Could this force be or be caused by dark energy?

[Tormod]

Wavelength - I don't think there is a need for an "external" force. Freethinker's explanation is fairly standard.

All things have a "potential" to move towards a state of rest. Because space-time is curved, objects of mass will follow the path of least resistance as long as nothing is stopping it.

In classical physics (ie, Newton) things pulled at each other. It is a good theory and it stands true for calculation in most cases. However, it does not cater for things like the speed of gravity and how gravity fields affect the passage of time. This was what Einstein solved with his relativity theory.

Here is a more detailed take on gravity:
Wikipedia: Gravity
http://en.wikipedia.org/wiki/Gravity

[Freethinker]

Quote

Originally posted by: wavelength?
FT, That does not answer my question. There is a force being applied to all objects of mass from (or is)the curvature of spacetime, this force must come from somewhere.

This force IS gravity. Or perhaps we can say that gravity is the name we give to that force. You seem to want to assume that some OTHER force from some other place is needed.

Are you familiar with Einstein's Elevator thought experiment?

Quote

It seems like all objects of mass are bubbles of matter in the medium of spacetime. Could this force be or be caused by dark energy?

Good question. At this point it seems that "dark energy" is the name we are assigning to the interactions we are observing. Perhaps as just a way to carry on a discussion about what is being observed. As I understand it, it works more like the opposite of gravity. It is a repulsive force causing an acceleration in expansion of the universe. Perhaps the dipolar component of gravity?

[Uncle Martin]

Is it equally possible that gravity is getting weaker over time? I'm talking millions or billions of years, not something recent. Does this also explain the accelerated expansion?

[BlameTheEx]

Uncle

I doubt it. If gravity is now weaker then the deceleration in the past would be greater than expected, but a reduced deceleration can't explain a complete reversal to acceleration.