(Mike Helland) wrote in message . com...

I have a question, matter causes space-time to curve, correct? What do
we call that phenomenon?

We call that phenomenon spacetime curvature. It's described by
Einstein's field equations for a gravitational field:

R_{\mu\nu} - \frac{1}{2}g_{\mu\nu}R = 8\pi T_{\mu\nu}

where R_{\mu\nu} is the Ricci tensor (contraction on first and third
indices of the Riemann curvature tensor), R is the Ricci scalar
(contraction on Ricci tensor), g_{\mu\nu} is the spacetime metric you
choose to endow upon your manifold, and T_{\mu\nu} is the
stress-energy tensor. It's all so simple: on the left-hand side you
have the curvature of spacetime, and on the right-hand side you've got
the essential description of the matter distribution that causes the
spacetime curvature. Of course, "curvature with respect to what?" is a
question you could ask, but that would take us into the details of
whether describing the intrinsic curvature of a spacetime manifold is
better than speaking of the extrinsic curvature of (M,g) embedded in
some higher-dimensional manifold.

Wasn't the title of this thread "GR doesn't make sense because SR is
wrong"? How can one hope to have an understanding of GR, much less
attempt to point out flaws in it, when one thinks that "The Special
Theory of Relativity says that nothing travels faster than light
because light is the speed of existence."? The speed of existence?
News to me.

I have not been following this thread, but just happened to see this.

Mike Helland wrote:
I have a question, matter causes space-time to curve, correct? What do
we call that phenomenon?

Gravitation.


Tom Roberts

Bilge,

I have a question though. If what I'm saying is right, that the time
we perceive in nature is a result of some other time where a
completely different nature (QM) interacts, that would mean that our
laws of nature only apply to our nature.

At the risk of misinterpreting what you mean, I can say that such
an idea is a topic debated in fundamental physics with many specific
ideas on what "some other time" means.

Cool. Would you mind pointing me to any starting places? I must not
have the right search terms.

Obviously any theory without general
relativity as a fundamental construct, must reduce to general relativity
in some limit, since general relativity is known to work for gravity
at the present time in the universe.

I know this might be more radical than you care for, but hear me out
on this. Does General Relativity really "work" for gravity? If General
Relativity says that Gravity requires curved space, curved by matter,
there is a phenomenon there where matter is curving space. If thats
so, the phenomenon needs a name. The way I see it, the best name for
what is behind space being curved by matter is gravity. That means the
whole idea behind General Relativity is self referencing, even though
the Mathematical models were devised to work.

If I understood your statement above, there is nothing wrong with what I
perceive as your idea. It just isn't possible to address it one way or the
other as it stands.

I think that the difference between this idea and other ideas is that
here we really understand why we cannot understand. Given your
statements about how difficult it is to verify any of the unifying
ideas we have, even if you do not agree with me, you must certainly
see where I'm coming from when I say that these studies go further and
further beyond our rationality, and therefore, beyond our
understanding.

Mike Helland wrote:

Tom Roberts wrote in message
Mike Helland wrote:
I have a question, matter causes space-time to curve, correct? What do
we call that phenomenon?
Gravitation.

This is my point. If GR says that gravity requires the curvature of
space-time, and the curvature of space-time is gravitation, as you
say, than its equal to saying that Gravity requires Gravity. Then we
really haven't said anything.

Not so. GR makes specific predictions of the results of experiments.No
credible experiment has falsified one of those predictions.

You're concentrating too much on explanations. Physics is about
theories that correlate the results of different experiments, not
about explaining things.

John Anderson

Not so. GR makes specific predictions of the results of experiments.No
credible experiment has falsified one of those predictions.

And I completely agree that GR has given us a useful tool in
understanding the effects of gravity.

You're concentrating too much on explanations. Physics is about
theories that correlate the results of different experiments, not
about explaining things.

I completely agree. My goal in learning in physics is alot more
similar to Aristotle's goals than contemporary physics' goals.

However, if you admit that a theory like General Relativity is not a
theory that explains gravity, but rather, how to interpret and predict
the effects of gravity, why would there be resistence to my suggestion
that GR says absolutely nothing about the true cause of gravity?

(Oh, and please don't get hung up on "true cause." I just think its
important to note that GR is 100% about the effects of gravity and
does not make any statements about the cause of gravity)

I have a question, matter causes space-time to curve, correct? What do
we call that phenomenon?
Gravity.

So to paraphrase GR, gravity requires gravity.
Thats consistent with what I've been saying.

Giving names to things is trivial. Establishing a theory
that is not falsified by experiments is much harder.

And establishing a theory that is not falsified by experiments and
that is not falsified by critical reasoning is even harder still. I
suspect we have no disagreement here.

Mike Helland:
Bilge,

What you are saying is what is that general relativity is not
formulated against a fixed background.

Not quite. What I'm saying is that General Relativity is extremely
useful for understanding the effects of gravity.

OK, then you don't realize that is what you are saying. This is
evident in your comment below:

I'm also saying that while GR gives us a great tool for understanding
the effects of gravity, and correlations between the effects of
gravity (I'm explaining the curving of spacetime as gravity as well as
the movement of objects along curves as gravity; which would be
consistent with GR's equation) its says nothing of relevance about the
actual cause and mechanics of gravity.

In general relativity, the "actual cause" of gravity is essentially
the same thing that "causes" newton's first law in newtonian mechanics:
Objects in uniform motion remain in uniform motion unless acted upon
by an external force. General relativity doesn't make the (unwarranted)
assumption about what "uniform motion" (i.e., "straight line") means
that newton made. In effect, gravity doesn't need a "cause" because
it is nothing but the "uniform motion" of objects through spacetime.
This may be a subtle point, but it's the basic idea behind general
relativity. Unless you believe that a stone thrown out in space needs
a reason to not continue in the direction it was thrown without changing
velocity (as per newton's first law), your objection to general relativity
boils down to newtonian bias in defining inertial motion.

Einstein made another observation. A body which is free fall has
no forces acting on it.
...
Einstein didn't have the advantage of observing astronauts, so he used
an elevator to argue that if no forces are acting on a body in free fall,
then gravity must not be a force...

And based on everything you know about QM, you aren't suspicious of
this line of reasoning?

No. General relativity is not a quantum theory and it doesn't bother
me in the least if a quantum theory requires a different description of
the universe in which spacetime itself ceases to be meaningful. I think
it's relatively clear that general relativity describes the universe
in terms of the four dimensions we observe.

I do, but my argument is more philisophical than physical. Perhaps you
could show me were I'm going wrong:

Lets say I'm standing at the edge of Helland's Pond. Beneath the
surface of this theoritical pond there exists a different universe
with its own unique GUT.

That makes the other universe intrinsically different. Such a universe
could conceivably have physics which is completely different from our own,
in which case it doesn't make much sense to try and use it for any
ontology without understanding the physics. One of the fundamental
questions associated with quantum gravity is whether or not a different
type of universe could even exist. That won't be known until (or if)
the reason is known that constants like \alpha exist. It might be
that this universe is the only type possible. Or, it might not.

When I throw a rock into this pond, I notice that the rock gets thrown
bcak to me. However, it does not re-enter my universe at the same
point in the surface of the pond where it exits my universe.

That possibility exists withing general relativity. There's no
need to resort to alternate universes.

Now, I can study this behaivor, perhaps to the point where I can
create a theory of formula to predict where this rock comes out and
how fast. And if the existing mathematics isn't sufficient, I could
probably even devise a system to explain the observations I'm making
of the rock coming out of the pond.

Sure, and with enough observations, you should be able to (1)
understand the physics of your hypothetical universe and (2) understand
the connection to this one. The fact that the two would be connected
begs the question of why you would consider two different universes,
though.

I could even write a theory to explain how the rock is going to come
out. But all that aside, I still have no idea how or why the rock was
thrown back from the other universe.

People used to have no idea why the sun rose and set or why lodestones
exhibited strange behaviour either, but lots of observations and study
explained those things.

The parellel here is that I believe (as long as my hypothesis is not
demonstrated as false) that our universe is created by the forces of
nature (including gravity and light + electromag and strong and weak),
and that is the GUT for our universe. Quantum Mechanics can be viewed
as its own universe wich will require its own GUT, and the observation
of light can be seen as the surface of my pond between these universe.

By definition a GUT is a theory which unifies nature. We already have
separate thoeries which are adequate to describe nature and that only
requires two theories. The goal is to find one.

In light of all this, we should see that gravity is alot like the rock
being thrown back. We can observe and theorize how the effects of that
action will work, and indeed, we have done so rather well with General
Relativity. However, it should not be difficult to admit that we
really haven't begun to discuss the mechanics of that action.

The "mechanics of that action" is no different than expecting a
rock thrown out in space to continue along its path without being
deflected. Requiring that path to be a straight line in the euclidean
sense is classical bias.

if one accepts that the universe isn't classical.

I'm thinking that we will need to clarify the term universe, if you're
willing to entertain my suggestion that QM and Classical Physics
shoudl be regarded as two different systems each requiring their own
unique unified theory.

Such a prospect would be very unsatisfactory for both physical and
philosophical standpoints.

Does that mean they're two different universes? Or maybe two different
existences in the same universe? I'm not sure how exactly to answer
those questions because, as someone here noted, its trivial to name
something. But it still needs to be done to clarify the situation.

A "universe" is self-contained.

Stephen,

: I completely agree. My goal in learning in physics is alot more
: similar to Aristotle's goals than contemporary physics' goals.
Why would you want to emulate Aristotle? He was wrong more
often than he was right.

Its not important whether he was right or wrong. The fact that he
essentially started physics means that the probability of him being
right is nearly impossible!

For example, lets take the theory that I developed over the last
couple weeks. None of that was obtained through hard work on my part.
It was people like Aristotle, Newton, Einstien, and everyone else who
added to the knowledge base that is the human memeplex that did all
the hard work. Chances are, that sooner or later they will be
corrected, but their work is still invaluable.

The reason it doesn't matter which of our historical figures is right
or wrong is because what matters in this field is the process one
takes to come to a conclusion.

Aristotle's goal in this process was to comprehend all phenomenon in
nature. Since we've used the scientific method to reach that goal, we
have realized that there are some things that we cannot comprehend. As
a result, the goal of physics changed. To be able to describe and
predict natural phenomenon.

While I think this is an admirable goal for science, and while I think
much useful knowledge technology can come out of it, it is simply not
as interesting to me as actually comprehending why. Its a personal
opinion.

That is why I take Aristotle's approach. (Un-knowingly of course, only
recently when confronted about my unorthodox goals in studying physics
I actually found most of this out.) And I feel that I have something
to contribute on this front. While it may be impossible to compeltely
understand physics, I do feel that I understand why I do not
understand.

The other reason I take this approach is because of the consequences
of the alternative. If we recognize that there is an observational
barrier in our universe, I believe that our mainstream science has the
mindset that explaining what is between us and that barrier will tell
us something about existence. They will continue to split things in
half until they get bored with infinity.

This is similiar to continually walking halfway between where you are
and where you want to go. It will take you a long time, and you will
never get there.

Mike Helland wrote:

Not so. GR makes specific predictions of the results of experiments.No
credible experiment has falsified one of those predictions.

And I completely agree that GR has given us a useful tool in
understanding the effects of gravity.

You're concentrating too much on explanations. Physics is about
theories that correlate the results of different experiments, not
about explaining things.

I completely agree. My goal in learning in physics is alot more
similar to Aristotle's goals than contemporary physics' goals.

However, if you admit that a theory like General Relativity is not a
theory that explains gravity, but rather, how to interpret and predict
the effects of gravity, why would there be resistence to my suggestion
that GR says absolutely nothing about the true cause of gravity?

(Oh, and please don't get hung up on "true cause." I just think its
important to note that GR is 100% about the effects of gravity and
does not make any statements about the cause of gravity)

Nor does ANY physical theory.

Theories correlate observations. They don't explain
things. Newton's laws don't EXPLAIN their consequences.

Physics is based on experiments. The experimental results
can be explained by many different theories. You can use
experiments to eliminate theories whose predictions disagree
with experiment. You can't eliminate alternative theories
that agree with all known experiments. If the "explanations"
that different viable theories disagree, which "explanation"
is correct?

Think about it.

John Anderson

Mike Helland wrote:

I have a question, matter causes space-time to curve, correct? What do
we call that phenomenon?
Gravity.

So to paraphrase GR, gravity requires gravity.
Thats consistent with what I've been saying.

Giving names to things is trivial. Establishing a theory
that is not falsified by experiments is much harder.

And establishing a theory that is not falsified by experiments and
that is not falsified by critical reasoning is even harder still. I
suspect we have no disagreement here.

In physics, theories aren't falsified by "critical reasoning" unless they
are logically inconsistent. In that case, they are useless, since
anyone ought to see that they are inconsistent from the day they
appeared.

Physics is an experimental science. Theories that are logically
consistent but which predict different results for the same experiment
get judged by the results of that experiment.

End of story. You need to think a lot more about the logical
basis of science.

John Anderson