41

Physics, Astronomy & Cosmology / Re: How can the field equation be zero while the Ricci tensor is not?

« on: 28/10/2017 20:42:27 »

But when deriving the Schwarzschild solution, after calculating the Ricci tensor (R^μν) and the Ricci scalar (R), from the spherical symmetries of the problem, both are non zero.

If so then that's news to me. Can you find a source on the internet which shows that to be true? Clearly from Einstein's equations in vacuo R = 0 so I can't see how it can not be zero.

How is it possible that the field equation are zero while R^μν and R are non zero?

They can't be. It seems to me that there has to be problem with your assertion above where you state that the Ricci scalar and tensor as zero.

Note: caution should be used when using the "/" operator in textual form. The expression 1/ab is defined as 1/(ab). I say this because you wrote 1/2*4 where you meant to write (1/2)*4. It really means 1/(2*4).

42

Physics, Astronomy & Cosmology / Re: Were Michelson and Morley wrong in their predictions?

« on: 20/09/2017 20:08:56 »

For those familiar with the experiment, If you think about the resistance a river would put on a ball moving directly against its current as being one or maximum resistance, and then a ball moving with the current as being at 0 or lowest resistance, the resistance travelling perpendicular to the current will be half of these two resistances added together.

There is no resistance that needs to be taken into account here. When a boat is moving in water at constant speed its because the force due to the propeller is equal and opposite to the drag force of the water on the boat. Therefore all one needs to do is consider an object moving at constant speed relative to a medium and that's what the derivations of the interferometer are all about. And there is zero resistance to the motion of anything moving relative to the "ether." If there were then the Earth would have slowed down in its orbit around the Sun due to a loss of energy. Since that hasn't happened there's no resistance.

43

Just Chat! / Re: Non theist but not atheist? What do you believe?

« on: 15/07/2017 16:42:09 »

David,
It appears as though your God concept is identical to the Christian God, omnipotent, all-knowing, etc.  If so, your God cannot think.  Thought, as humans experience it, involves the creation of new concepts, ideas previously unknown.

Regarding your comment "the Christian God." The God of Christianity is the same God as that of Judaism and Islam, i.e. The God of Abraham. Its unfortunate that most people who aren't Muslims are completely unaware of the fact that the God of Islam is the exact same God/being as that of Christianity and Judaism. Its also unfortunate that those who know that the God of Islam is the God of Abraham also believe that the Christian God, the God of Judaism and the God of Islam are all different Gods even though they all believe that their God is the God of Abraham. That's extremely illogical. I've had that discussion with a few Christians and they hold that to be case because they have "different beliefs" about God. That's pretty sad logic to me.

A anyway, since when does human thought require the creation of new concepts? A new thought such as "I'm going to choose to have OJ for breakfast then I'll shower and go to work" does not constitute the creation of a new concept.

I don't accept that the God of Abraham (GoA) knows everything. I don't believe that the Bible even states that God ever said that he did know everything. Had that been true he never would have regretted creating Man and had have no need to destroy them with a flood nor would God have regretted making Saul King.

I did a bit of searching today on this notion and learned that my not accepting that the GoA not knowing everything is hardly a new thought. I learned that his notion is referred to as Open Theism and is a evangelical and post-evangelical Protestant Christianity concept. See: https://en.wikipedia.org/wiki/Open_theism

This has been decribed in short here: http://www.desiringgod.org/interviews/why-does-god-regret-and-repent-in-the-bible

This is a huge and important issue. Back in the mid-1990s, I was embroiled in disputes over what is called “Open Theism,” which argues that God is open to the future in the sense that he does not have exhaustive knowledge of what is coming in the future.

Note that the person who wrote that holds it to be wrong with his reasoning being that its akin to us saying "I'm going to regret doing X but here I go and do it."  I consider that to be nonsense. Especially when the consequence is killing mankind and since it removes free-will. At least in my opinion. Christians seem to hold that GoA has he same emotions we have and they at the same time hold that the GoA doesn't have the same emotions. I can't accept arguments with such logical contradictions. Especially when its not backed up in the Bible. The author's arguments are not logical ones, they're all guesswork with him almost always using terms like "I think" and "may have/be". For example

He may well be capable of lamenting over something he chose to bring about. And God may be capable of looking back on the very act of bringing something about and lamenting that act in one regard, while affirming it as best in another regard.

So here we see him use the phrases "may well be capable" and "may be capable". He also bases his argument on the verse

The Glory of Israel will not lie or have regret [or repent], for he is not a man, that he should have regret [or repent].

One is forced to interpret "The Glory of Israel" as being identical to "God." But notice that this is not God speaking but the author, who may have been Samuel himself but nobody is certain of that but Jewish tradition holds that it was Samuel that wrote the books of Samuel.

Christians etc will always argue that the books of the Bible are the "inspired word of God" meaning that God put what to write in the minds of the authors and then they just wrote down what God told them to. However there's a place in the New Testament where it said that a few of the apostles were arguing over the meaning of something. If what was in their minds was the inspired word of God then there'd be no argument among their meaning between  the apostles.


Note: When I speak of what's in the Bible I do so not on someone else's interpretation of its content but what I actually read in it. Someone once suggested to me that I read the Bible cover to cover, every single word, at last five times. I've only done it twice. I'll keep going though since the Bible is the most widely read book that there is.

The Bible is flawed too. I've read places where there are contradictions. I think it was in the two stories of how King Saul (?) died. If it wasn't King Saul it was how someone else died. But they contradict each other. I also found it extremely odd that in Numbers the exact count of the tribes were almost always rounded off to the nearest hundred. There were never numbers like 45,234 people. There is one place where the count is rounded to the nearest 50, i.e. the tribe of Gad.

There may be places in the Bible where men have stated that God knows everything but that's different than God himself having stated it. In the book of Job God is held to have made many statements about his abilities but nobody is sure about who wrote that book and whether its supposed to be as told by God, being a real story with actual statements held to be made by God or whether its merely a story told an attempt to explain something.

Thus it would seem as though such a being cannot create anything, including a universe with animate life and humans.

Not having any new thoughts doesn't imply that such a being cannot have an original physical creation of something such as the universe.

What is the use of such a God concept in a rational discussion? 

While I don't accept David's view on the definition of God it doesn't seem to me that one cannot have a rational discussion about such a God which is still useful. In fact there are always discussions of that kind going on as their have been since the creation of such an idea.

44

Just Chat! / Re: Non theist but not atheist? What do you believe?

« on: 13/07/2017 00:36:53 »

Scientists are the most inclined to doubt the resurrection of Christ... Stephen Hawking says he does not believe in God, because before the big bang, there was no time for God to exist in.

First off, a person who is a "non theist but not atheist" is called an agnostic. I've gone back and forth between agnostic and theist. An atheist has a poor logical position because he holds that God doesn't exist. Since it's not logically possible to prove that something doesn't exist then the atheist must believe it with no proof. Do you know what its called when you believe something when you don't have proof of it? It's called faith. Frankly I could never have enough faith to be an atheist because I think more logically than atheists do.

Second, I believe that Hawking is a smart man. But with all men, smart or otherwise, he has said some dumb things, and that was one of them. Where exactly did he say that anyway? We have zero knowledge of what happened back to a certain instant of time and before that we know nothing. As stated by Peebles in Principles of Physical Cosmology (1976) page 6

If there were an instant, at a "big bang," when our universe started expanding, it is not in the cosmology as now accepted, because no one has thought of a way to adduce objective physical evidence that such an event really happened.

and that's as true today as it was in 1976. There are even ideas of multiple universes from which an advanced civilization might actually create a universe from their own, leaving their own universe intact. Such a universe is referred to as a child universe. Suppose that there is a scientists in such an advanced civilization who created our universe designed as he chose fit. Then, by the definition of the term, that scientist would in fact be God.


e are theorists today who hold that the universe is infinitely old such as proponents of the Pre-Big Bang Scenario


 Although Christians believe Jesus Christ pre-incarnate is the Father of Eternity. From outside fills the universe with His presence.

What do you believe? In a god, in God, in a higher power, or in an intelligence behind the universe...?
[/quote]

45

Just Chat! / Re: ‘inhumane treatment’ of pain patients

« on: 30/06/2017 20:03:35 »

If anybody would like to read a story which will break your heart then I recommend reading the following:

The Other Victims of the Opioid Epidemic June 1, 2017, Glod S.A. N Engl J Med 2017; 376:2101-2102
http://www.nejm.org/doi/pdf/10.1056/NEJMp1702188

46

Just Chat! / Re: ‘inhumane treatment’ of pain patients

« on: 30/06/2017 19:36:24 »

If you want to talk about inhumane treatment of pain patients:

My friend, having been diagnosed as having Weigners disease, was told she had 2 years to live.

16 years later, having been inadvertently infected with Hep C 10 years earlier by the hospital conducting her care for all those years, and having been prescribed a steadily increasing dose of opiates for the pain associated with her crumbling facial bones and neck vertebrae - guess what?
NHS brings in a zero tolerance policy regarding long term opiate prescription and during a hospitalization for a minor fall decided to put their Hep C patient into forced opiate withdrawal.

For those of you who are not familiar, a forced opiate withdrawal is life threatening for a Hep C patient.  Withdrawal exacerbates the Hep C.  The exacerbated Hep C causes damage to the liver, and my friend 'the Weigners patient' that was requiring the pain killer was left unable to ingest opiates.

I've never been so angry in all my life.  I printed the Hep C info off the net and gave it to the doctor responsible for the decision who couldn't find enough nurses to put between us before he slunk off.  I daresay he hadn't bothered to read my friends file that had built up over 16 years to require a trolley of it's own...
...but why would a trained doctor put a regular Hep C patient into forced withdrawal from a 16 year opiate prescription anyway?
Based on the fact that a forced withdrawal will exacerbate Hep C and destroy the liver, what benefit could there be in forcing an opiate withdrawal on a Hep C patient?

Never assume that a doctor is intelligent merely because they're a doctor. I know that from an experience with a doctor I once had. She had the audacity to compare what I was taking for chronic pain with her experience taking a low dose Percocet.  My last exchange with a physicians assistant pissed me off big time because she claimed my dose was way too high, even though I've been on and off opiates for 12 years now. Dumb woman!!!

47

Just Chat! / Re: ‘inhumane treatment’ of pain patients

« on: 30/06/2017 15:41:59 »

opiate-cocaine combo is a specific synergistic thing which people are known to indulge in.

What does that have to do with chronic pain patients use of opiates? In any case that doesn't address my question  which is why doctors care about that? I.e. does it mean a lower quality of life than living with no opiates and having the pain?

Besides, a visiting nurse can make sure that the opiates are taken exactly as prescribed.

48

Just Chat! / Re: ‘inhumane treatment’ of pain patients

« on: 30/06/2017 15:40:17 »

I have a neighbor with severe chronic pain, who takes large amounts of very powerful opiates every day, and she gets drug tested routinely. But she ascribes this to her Dr. wanting to verify that she is in fact taking the drugs (instead of selling them), not necessarily to screen for other drugs in her system.

Pain contracts require patients to refrain from alcohol and recreational drugs. Violation means being taken off opiates.

Note: All opiates are powerful. Being on a high dose only means that their body has adapted to the lower dose and only a higher dose will work. I does not mean the patient is experiencing euphoria from them or is high. That's from personal experience and my "patients education" in opiates.

I'm concerned that this line of discussion is detracting from the real issue which I wanted to discuss. The refraining of giving opiates to chronic pain patients because a few of them abuse them.

What almost all doctors refuse to understand is that they can always require the opiates be distributed by a visiting nurse who keeps them in a safe and gives you one days worth. Or they can visit in the morning and night and watch you take the extended relief opiates like oxycontin or mscontin. Or even a pain pump.

49

Just Chat! / Re: ‘inhumane treatment’ of pain patients

« on: 30/06/2017 14:12:22 »

Pete, cocaine and opiates are quite different types of drug; totally different family and mechanism.

Yeah. I know. But that doesn't address my question. I.e. why put opiate users on a pain contract requiring urine screening?

Patients are never placed on pain contracts when taking meds like Xanax and you can die from a Xanax overdoes.

50

Just Chat! / Re: ‘inhumane treatment’ of pain patients

« on: 30/06/2017 08:06:36 »

Something that I've never understood is the reason for urine screens to test for cocaine when a person is being prescribed opiates. What I want to know is what the danger is of being on opiates when using cocaine. And please don't bore me with anecdotes about people dying from overdoses of the combination since I can provide just as many anecdotes about people who have used both at the same time a huge number of times and were fine.

I'm thinking about cocaine users with chronic pain who aren't prescribed pain-killers for that reason. It's inhumane to do nothing about the pain. Why? Because some people will kill themselves because the pain is intolerable. That's something I have first hand experience in. And I'm referring only to those situations when all else has failed. Thanks.

51

Just Chat! / ‘inhumane treatment’ of pain patients

« on: 30/06/2017 05:37:20 »

I noticed that one of my fellow moderators suffers from chronic pain like I do. I thought she'd appreciate this article

https://www.statnews.com/2017/02/24/opioids-prescribing-limits-pain-patients/

It makes two excellent points

In effect, pain patients currently taking opioids long-term have become involuntary participants in an experiment, with their lives at stake.

To its credit, the guideline endorsed treating patients as individuals, not numbers.

Unfortunately doctors don't in general have a solid understanding of pain meds nor do they understand the meaning of statistics.

52

Physics, Astronomy & Cosmology / Re: How do I explain gravity to my children?

« on: 29/06/2017 19:26:29 »

-

I am getting confused about gravity! When it comes to gravity what do I tell my kids? Are we still telling our kids that an invisible force is pulling them towards the centre of the earth? The shape of space/time is the reason we don't float around? What would you suggest? 

Yes. We are still telling our kids, and all scientists, that an invisible force is pulling them towards the centre of the earth. It has always been true that the force of gravity, in fact all forces, are not visible, at least not to the naked eye. You still tell  them that they are breathing an invisible gas to stay alive aren't you?

Try explaining it like this - Around all planets there is a field of force, one that cannot be seen. When an object is place in that field the object is accelerated. When Einstein came along he showed that what we observe in an accelerated frame of reference is identical to what we observe in a gravitational field (there are caveats to this which are hard to explain to children). Einstein also showed that the matter which creates the field also alters both time and space.

53

General Science / Re: Could more intelligent beings than us have evolved since the Big Bang?

« on: 28/06/2017 14:09:52 »

George says:

Brian Greene in his book 'The Fabric of the Cosmos' claims that time throughout the universe is the same due to inflation. Considering the time it's taken, since the Big Bang, for the evolution of human beings, could any other life exist elsewhere in the universe that's more intellectually advanced than us?

What do you think?

I think that comment by Greene is either misleading or just plain wrong, depending on exactly what he meant when he said that.

But yes. That's quite possible. Even probable. Its also possible that the universe is infinitely large and if their are galaxies and stars throughout the universe then its 100% certain that much more advanced beings than ourselves exist somewhere in the universe.

54

Physics, Astronomy & Cosmology / Re: Do neutron stars spin? If so, why, and how fast?

« on: 24/06/2017 18:39:21 »

has anyone ever said before that neutron stars and black holes spin at light speed or near it because all the composite neutrons are packed so tightly that there effort to spin turns the whole star? I was always told to think of it as a soup which doesn't make much sense.

No neutron star as ever been found any part of which moves at near light speed. The fastest ever found moved at 24% the speed of light. The fastest spinning neutron star found yet is a pulsar 18000 light years away. Its catalogued as PSR J1748-2446ad.

And its well-known why they rotate that fast. A neutron star forms when a star collapses in on itself. All stars rotate naturally because the matter from which they were formed was originally moving and as such the resulting star has some angular momentum. As the neutron star is formed from the shrinking star the rate of spin increases in order for angular momentum to be conserved, If the star had a companion then the mass gained from stripping the star of matter also goes into increasing the angular momentum of the neutron star.

See: https://www.newscientist.com/article/dn8576-fast-spinning-neutron-star-smashes-speed-limit/

55

New Theories / Re: New theory of dark matter and quantum gravity.

« on: 11/06/2017 23:05:29 »

The first thing to get out of the way is that the exponential functions governing the wave functions of electrons are just heuristics.

What so you mean by that precisely.

There is a probability of 1:4.17 x 10^42 that the electron will appear at at least some distance beyond the Van Der Waals radius of the atom to which it belongs. So this is a tiny probability that the electron volume probability density of an atom extends somewhere beyond the Van Der Waals radius, i.e. an electron can pop-up somewhere beyond the radius of the atom for a very brief amount of time before it interacts with a photon and changes position again.

That is incorrect. You misinterpreted the probability incorrectly. The probability associated with the wavefunction refers to the probability of finding an electron in a specified volume of space when the position of the particle is measured. It doesn't refer to the electron popping up somewhere nor does it mean that a photon will collide with it changing its position.

I strongly recommend learning more about the wave function and its correct interpretation. See:
https://en.wikipedia.org/wiki/Wave_function

I also recommend that you learn the philosophy of physics and why the notion of proof is not part of science. Here's a place to start. The following video is of Alan Guth, an MIT cosmologist/particle physicist. Highly respected and well-known in his fields.

http://www.newenglandphysics.org/common_misconceptions/Alan_Guth_04.mp4

56

Physics, Astronomy & Cosmology / Re: How does Heat Relate to Gravity?

« on: 11/06/2017 20:32:56 »

The first thing to say is that in normal usage, heat and temperature are used interchangeably.
In Physics, they are quite different things, and the amount of heat in a substance is proportional to its mass and (sort of) proportional to its temperature (if you ignore phase changes).

Your response is based on the common misconception that a body "contains" heat. This is incorrect. Heat is thermal energy in motion, i.e. Heat is the amount of energy flowing from one body to another spontaneously due to their temperature difference. You were thinking of thermal energy. A body can have/contain thermal energy, but not heat.

57

Physics, Astronomy & Cosmology / Re: How is the mass loss of the Sun calculated?

« on: 09/06/2017 23:05:50 »

These incredibly precise astronomical measurements are able to detect extremely small changes in the mass of the Sun. But any changes have been too small to measure with current techniques.

Evan - Can you please clarify this response for me? These two statements seem to me to contradict each other. In the first sentence you state that we are able to detect extremely small changes in the Sun's mass while the second states that they're too small to be detected by current techniques. Huh?

58

General Science / Re: Could you see the past if you could travel faster than light?

« on: 01/06/2017 19:53:27 »

Jack wants to know:

If you went faster than light, which i know is theoretically impossible - but if you could, would you see that light from before and thus see the past?

What do you think?

Yes.

Jeff - I believe the OP is asking about the seeing the past of the place that they're located, e.g. Earth. While we can see the past of Proxima Centari we can't see the past of Boston.

59

New Theories / Re: On Einstein’s ‘Light Box’ thought experiment.

« on: 29/05/2017 13:56:10 »

If we send the light by the angle φ (tangentφ = c/v); ...

It's unclear what angle you're referring to since c/v is not the tangent of any angle in that diagram.

Are you referring to the angle tan φ = L/(vt/2)?

at this position the path of light will be perpendicular line according to mirrors //

What does "perpendicular line according to mirrors" refer to?

Sorry but your response makes no sense. Please restate it.

60

Physics, Astronomy & Cosmology / Re: Is a radial geodesic possible towards a rotating body?

« on: 28/05/2017 14:23:19 »

I am thinking of a geodesic that is 'geostationary' for want of a better term.

It's quite unclear to me what you mean by "geostationary." Please define that term for me.

So that it is always heading towards the same point on the central body.

If a body is in free-fall towards a rotating body then (1) it will be moving on a geodesic in spacetime and (2) will not be moving directly towards the body since spacetime dragging will sweep it along the direction of rotation.

Therefore it has to rotate with the body. At some radial distance it has to rotate at the speed of light to keep up.

Why?

FYI - You're confusing the term "rotating" with "revolving." A body which is orbit of a gravitational body is said to be "revolving" around that body. A body which is spinning is said to be rotating.