disarray

Gilga-flesh says that "Ironically plenty of inmates try to kill themselves, apparently agreeing with my viewpoint."

while

John's rebuttal is that "People on death row appeal the sentence hoping for life in prison instead. They presumably know more about it than you do."

On the face of it, I would suggest that Gilga's comment is more likely to have merit, simply because it refers to some inmates, while John's comment implies that all those on death row appeal (or presumably would appeal) their sentence hoping for life imprisonment instead...and hence is likely to be a false generalization.

Obviously thousands of inmates have attempted suicide, and thousands of inmates have completed suicide, for one reason or another. Some because they did not want to be hanged, for example, some because they were extremely ashamed and/or depressed, etc. In any case, they chose to end their lives rather than to continue living, and usually we don't really know whether they would have still wanted to end their lives if they had been given a lesser sentence, e.g., 20 years. Indeed, many Native Americans, for example, hang themselves in their cells from the sheer (arguably, somewhat culture-specific) trauma of being captured and enclosed while under the influence of the a depressant (alcohol), knowing full well that they would be released in a day or two given the nature of their "crime" e.g., disorderly conduct and drunkenness.

As for John's argument, I strongly suspect that not everyone on death row would appeal their sentence (of death) or would even choose to live if they had the the choice to do so. Obviously many people who are not incarcerated are so disenchanted with the idea of living any longer that they are willing to actively or passively end their lives as soon as convenient/possible even though they are not precipitously dashing themselves out some 12th story window, so it seems reasonable to presume that there are some inmates who, given the choice to live if only they made, for example, further appeals, similarly couldn't be all that bothered resisting death at the hands of prison officials, particularly if such a death was reputed to be quick and painless, thereby escaping a continuation of their futile, unendurable, and seemingly meaningless lives in prison. (Let us not forget that life in many prison cells is something of a subdued but prolonged form of torture. The reality is that a person who successfully gained a reprieve from the death sentence may later find prison life so unbearable, at least on some days, that he sincerely wishes he were dead...or had been put to death).

Finally, there may be the factor of self-determination, personal pride, autonomy, etc. It is likely that a person is willing to take his own life, given that he is calling the shots, whereas the same person would resist others, e.g., 'the establishment' taking his life.

Gilga comments that instead of letting the inmate decide, perhaps the victims and/or their surviving relatives should have a say instead: "They might veto to allow the criminal to suffer or might relish the notion that the perpetrator is dead far more so." I think it highly unlikely that this would happen (e.g., in the U.S.). For one thing, what happened to letting the legislative/judicial/executive aspects of government make such decisions...are we to willy-nilly let disgruntled and vindictive victims/relatives mete out punishments as they see fit? And what happens if vindictive victims think that the death penalty is the worser option while the inmate prefers death over life in prison? In any case, such a proposal seems to focus on the role of vengeance in our legal system, and I would have thought that our enlightened culture was moving away from that sort of attitude.

Nor can I foresee in the immediate future that the legal system would allow those convicted to decide their own fate, as giving them the option to choose between life in prison or a death sentence is tantamount to offering them the option of committing suicide. Indeed, in the sci-fi scenario where a society operated in this way, one could envisage the possibility that the legal system would make the prospect of life in prison so unpalatable as to encourage convicts to rush to the gallows (electric chair, gas chamber, or what have you) rather than deal with the harsh realities of life in prison. (Though in States where euthanasia is legal or 'virtually legal', one wonders who is to decide who has the right to have themselves euthanized and who doesn't....Would not an inmate who faces the prospect of life in prison unacceptably onerous, or indeed, who finds prison life unendurable after, say, a few years have passed, also have the right to end his own life? Where does one draw the line between suicide and euthanasia....shouldn't we all have the freedom to die when we want?)

Finally, I would point out that the prospect of death means different things in different cultures. I have read that some Easterners (e.g., Buddhists, Hindus) have the bizarre diversion of drawing straws to see who jumps out of an airplane to his death, and thus to the next incarnation. This tale may or may not be true, but it makes the point that not everyone fears death and for some, dying is no big deal. In some other societies, the death sentence could be construed as a form of torture, since it is hastens, for example, the (presumably guilty) inmate's descent into hell and everlasting torment.

The 'expansion simulates gravity' theory is inconsistent with observation.

How can it answer the "why masses gravitate' question ?

The article does address this and other weaknesses of a 'basic' physical expansion concept, but comes up with a modified version that supposedly avoids these problems. Did you read the article?

I for one would stop asking questions if a scientist just said that gravity was, unexplainable beyond that it "just is", much like the electric charges between particles;.... and indeed, the equation for the degree of attraction (re distance) is virtually the same.

However, I did post recently a credible site that sought to actually give an answer to the "Why" it happens that was purportedly consistent with Relativity and indeed is based on the physical expansion of the universe. No comments?

Again, the article is at http://www.mathpages...77/kmath077.htm

.But just how the Earth is pushing up against this medium of gravity field I have proposed , I am not sure . The rubber sheet model is too upside down in its modelling , it invokes more questions than answers
. I am trying to think of an alternative to a rubber sheet model ? Like large dense swarm of honey bees surrounding the earth , pressing down on us . ( joke )

The only theory that I have come across with respect to the earth pushing up, so to speak, is the physical expansion concept (which, I gather, is the result of the expanding universe):

"Beginning with the naïve idea of physical expansion as the cause of gravity, we are compelled step-by-step to the conclusion that the effective metric of spacetime must be contracting around massive bodies. If we examine in detail the requirement for the surface of an object to be accelerating outward in terms of the local inertial frames, even though the surface itself is stationary, we find that this “accelerating in place” implies that space is curved in time, and the rate of proper time is lower near massive bodies. This leads to the curved spacetime interpretation of general relativity, which of course gives a very satisfactory representation of all known gravitational phenomena."

http://www.mathpages.com/home/kmath077/kmath077.htm

This is an interesting article, though I don't know how sound it is.

Mike asks "WHY is there not an ' Aether like Medium ' within space-time , for gravity waves to propagate? When nearly every other wave , vibration , and oscillation , in the entire Universe , uses such a type of facility to efficiently propagate its energy or information ?"

I agree that the "Why" part of this is too vague. Really, I think that he is just making the observation that it seems improbable and inconsistent (with the 'norm') that gravity waves don't seem to need a 'medium' in which to propagate when virtually every other wave, etc. does....and that perhaps this apparent anomaly might be worthy of further investigation. (While others on this forum constantly retort, 'been there, done that....found nothing...maybe in the future...next question).

So in a sense, asking "why" is a little 'presumptuous' in that it presumes the generalization that all wave-like 'entities' need such a medium, which is an 'intuitive' and unproven generalization based on mundane experience, not solid science.

My own armchair philosophy hunch, which I supported with quotes from various science sites further above, is that space, 'time', gravity, and content (e.g., matter/energy/force) are all mutually dependent or inclusive. Thus, gravity (waves) could not propagate through some presumed 'nothingness' or 'multiverse fabric' without and until all of the four ingredients existed at once.

So yes, space is an elusive and perhaps illusive concept (and maybe entity), but space/time/gravity/energy-force is, a combined 'product' that came into existence over 14 billion years ago...(not trillions or some indeterminate number), so, given mathematical speculations that there is indeed a 'multiverse' (i.e., other universes), it seems possible that the question is not really 'what is space that gravity and other things can travel through it' but rather what are all of these things combined...and that is where, I guess, one just gets back to the basic buck-stops-here answer that 'things just are as they are'.

I tend to say "philosophical" as opposed to "scientific" hunch in this regard, because, apart from the opinions of various scientists, it seems to me that the Big Bang took place under what one might call 'primordial' or 'pristine' conditions, i.e., nothingness. (As Malraux, as I recall, once poeticized: "Being is the flaw in nothingness".) That is, there was no God with a particular personality that fashioned the universe in a particular way. Thus, as I think Leibnitz remarked, the universe could not be any other way than what it is....one could not just have 'space' or just have 'time' or just have 'gravity' or just have 'matter-energy', it's all or nothing. For Leibnitz then, the universe was as perfect as it possibly could be.

Disarray: I do not know whether scientists themselves could or should focus a little more on looking for cause-effect questions (for the sake of our future, or whatever).

I don't quite follow your point - lots of science is about understanding mechanisms of cause and effect. In physics this us usually understood mathematically.

I was rephrasing Mike Smith Cosmos' comment: "we need a lot more WHY , areas explored. Do we not ?"

My line of argument was that "why" questions do indeed become rather pointless philosophical vagaries unless one can phrase the "why question" in a way that more specifically resembles scientific investigation , e.g., "what causes" type of questions.

I take your point that science does indeed do plenty of investigation of causes, as long as the answers seem to be useful....And indeed, evolutionary psychologists point out that the brain is so effective because it is so goal oriented, as opposed to just being idly speculative. One wonders, though, whether a bit more idle speculation would ultimately bring productive results. Indeed, I wonder how many inventions and discoveries began, for the most part, with idle speculation, e.g., Einstein's "I wonder whether one could see ones reflection in a mirror held in front of ones face if one was traveling at or near the speed of light." On the face of it, what possible use could such a question seem to have.

As far a what is meant by the terminology and geometry behind spacetime. The best answer is learn the calculations

Well, yes, of course. But it does help to learn the concepts as one learns the calculations, and for most people, that often involves asking questions such as "what causes....", "why does that happen," "what if," etc. As I mentioned previously, people have different types and configurations of learning "intelligences," which means that many people, especially when it comes to the mystifying concepts of relativity and quantum theory, will nowadays want all sorts of educational aids (e.g., metaphors, illustrations, stories, film clips, descriptions, explanations, etc.) in addition to just learning the math. In many people's minds, just learning the math is just rote learning (despite the fact that those proficient in math can see logical connections that the average person can't). And rote learning, as we know, may be effective, but is often discouraging and unsatisfying.

You should read up on metaphysics and the philosophical implications of modern physics. I hope someone here can offer you some suggested reading as I cannot.

One can indeed find information about different theoretical and philosophical perspectives about such things as relativity.

Philosophy of science example:

Harvey Brown takes sides in a debate about the explanatory role spacetime plays. (Although Brown repeatedly expresses solidarity with those who deny that spacetime exists, all parties to this debate are substantivalists -- they accept that spacetime exists. So Brown, too, accepts this view, for purposes of his argument). According to (what Brown alleges is) the dominant view among substantivalists, the geometrical structure of Minkowski spacetime plays some role in explaining why moving rods shrink and why moving clocks run slow. Brown rejects this view. He asserts, instead, that in order to explain why moving rods shrink we must appeal to the dynamical laws governing the forces that hold the parts of the rod together. The geometry of Minkowski spacetime plays no role in this explanation.

http://ndpr.nd.edu/news/25025-physical-relativity-space-time-structure-from-a-dynamical-perspective/

Also, one can find information about the philosophical (social) implications of Relativity:

Einstein’s theories of relativity have not only affected our daily lives in such basic ways as how we heat our homes, reach our destinations, and measure our days. His theories of relativity were used by philosophers, politicians, and activists to turn moral philosophy upside-down. Relativity fueled postmodernism and philosophic relativism.

https://helix.northwestern.edu/article/einsteins-theory-relativity-implications-beyond-science

And of course, one can find information as to how Relativity affected philosophy in general:

General relativity raises questions about the relation between physics and geometry, denying the latter its traditional role as an a priori discipline. That is the main philosophical relevance of relativity theory. But the theory also bears on the traditionally metaphysical dispute whether all motion is relative and whether space and time are relations among things or exist independently. Both sides of the metaphysical debate cite relativity as supporting their position.

http://forums.philosophyforums.com/threads/philosophical-implications-of-einsteins-theory-of-relativity-12199.html

In general, I think that the distinction between "how" and "why" is often a gray one, just as, often, is the distinction between science and philosophy. Indeed, both fields tend to have their roots in magic, myth, and religion.

The question is are you looking for a mathematical description of the some mechanisms - so some calculations of some observables that we can measure - or do you want more? If you want more, then you are really getting into metaphysics and maybe religion - both of which cannot give you clear answers.

Well, perhaps giving accurate answers to questions from the general public about Relativity and Quantum theory seems impossible because of the higher math knowledge needed.

But as I look through hundreds of answers about general science questions, including those about gravity and relativity, I in fact see that one can make an attempt to give some sort of answer to just about any question without resorting to higher mathematics:

Q: What keeps an airplane in the air:

A: Four forces keep an airplane in the sky. They are lift, weight, thrust and drag. Lift pushes the airplane up. The way air moves around the wings gives the airplane lift.

Q: What property of matter causes geodesics to curve near them:

A: Matter produces gravity. We don't exactly know how this works because we do not have a sufficiently detailed theory of gravity that covers the graininess of matter and energy in a 'quantum theory of gravity'. Anyway, gravity according to general relativity is equivalent to the geometric properties of space-time; in fact they are equal and inseparable descriptions which you are free to move between. Geodesics are geometric objects which represent the straightest possible line that can be drawn between two points, so whenever you talk about what geodesics look like, you are invoking the geometric description of gravity and not its familiar Newtonian description in terms of forces. Geodesics curve near matter because the geometry of space-time is curved...another way to say that gravity is present. Your question is now equivalent to asking why it is that on a flat piece of paper, a straight line is 'straight'. It is the result of the fact that the background space is the way it is. https://einstein.stanford.edu/content/relativity/qanda.html

I do not know whether scientists themselves could or should focus a little more on looking for cause-effect questions (for the sake of our future, or whatever). I do not know whether an increased focus on causation would lead to greater scientific progress, particularly when a slavish focus on cause-effect may hinder progress in the field of quantum theory. However, it does seem that looking a little more for explanations, as well as for what measurements reflect what happens, and how we can make predictions, and how we can make rockets, etc., might be productive.

I think that for the most part, people who read about scientific discoveries or inventions and ask "why" are not usually looking for any ultimate philosophical (religious or poetic) answers, e.g.,

• Why is there something rather than nothing at all?
• Why does light exist?
• Why is the cosmological constant what it is and not something else?

but rather they are interested in looking for cause and effect relationships (as is perhaps, human nature, to do so), e.g.

• What causes the universe to expand?
• What causes the sky look blue?
• What cause airplanes to stay in the air rather than fall to the ground?

Indeed, I would suggest that most basic books for kids and adults that are filled with questions and answers about scientific facts generally follow the format of looking for causes.

So when a layperson asks questions about Relativity and Gravity, they are, like classical scientists, looking for cause and effect relationships.

• What property of matter causes geodesics to curve near them?
• Would the collision of two photons cause them to slow down as a result?
• What factors determine the strength of gravitational force?

Perhaps it would help the general public if scientists were more clear that they either don't know of a specific cause (e.g., the causal connection between energy/momentum and gravity), or that they don't think that there is a classical cause-effect relationship (e..g, as sometimes is claimed in quantum mechanics), or if there are a variety of causes (as there are in global warming), or if the causes are not what they seem (e.g., the fact that coffee drinkers have higher rates of cancer is not caused by the coffee, which may actually be preventive, but by the fact that coffee drinkers on average smoke more than non coffee drinkers.

Ajb: You state that "The best we can do is hand you a model and we can discuss mechanism within that model. But really the question why is one for philosophy."

I presume that science can often tell us the why of things better with some phenomena than with others, e.g., thunder, volcanic eruptions, rain, etc.

I agree that the question might be one for philosophy, if by that you mean the philosophy of science (e.g., the sort of lateral thinking involved in Hume and Einsteins efforts) as opposed to the sort of idle armchair (metaphysical) philosophizing that logical positivism tried to put an end to.

Ajb: You state that "The Einstein field equations say 'geometry/gravity = matter/stuff'. The 'stuff' is mathematically including in the equations as the energy-momentum tensor associated with the 'stuff' - loosely it is the fact that 'stuff' has energy and momentum that connects mass and gravity/ '

Ah, so if scientists don't understand just why it is that the energy and momentum of matter/stuff is connected with gravity, then there is no benefit at this point to ferret through textbooks trying to find an explanation that is not (yet) there. And again, is there any possibility that the expansion of the universe has anything to do with such energy/momentum.

As an aside, is it a fair statement to say that the most significant advancement that Einstein made over Newton, when it comes to gravity, is the equivalence principle?

Ajb: Thanks for the comment about the present lack of deeper explanations for the attraction between, say, the sun and the earth. Science sometimes seems to be a mixture of descriptions and explanations. Scientists seem to be more easily satisfied with just the former (as long as it works and as long as the model fits the measurements) than those with more philosophical inclinations. But again, I have read in a few places that scientists don't particularly understand why bodies with (esp. greater) mass attract.

Could you elaborate on this relevant and very recent statement of yours though:

"Massless particle still carry energy-momentum and so can act as a source of gravity."

This statement seems to hint at a 'genuine' explanation as to the connection between mass and gravity (and even, as you state, massless particles).

Ajb: So do we even have an explanation for the basic equation, viz., that the gravitational force one object exerts on another is related to the mass of the two objects and the distance between them.

(Apparently, to be more precise, increasing the size or radius and keeping the mass the same will cause gravity to decrease. On the other hand if one decreases the radius and keeps the mass same, gravity would increase. But if the density is constant i.e. the mass to volume ratio is constant, then the gravity will increase if one increases the radius.)

In terms of relativity, 'heavier' objects (e.g., the heavier planets in our solar system as opposed to the lighter ones) have a greater impact on the spacetime fabric (as the usual spheres on a net illustrate). But does Relativity give an explanation above and beyond this description as to why this is so.

Again, I don't think that scientists generally presume to have all the answers as to the accuracy of Relativity, e.g., :

"Mass is linked to space in a way that physicists today still do not completely understand." http://hubblesite.org/reference_desk/faq/answer.php.id=58&cat=exotic

Of course, the equivalence principle states that gravity gives virtually the same effects as acceleration (hence, time dilation). But how does one get from that principle to an explanation for light curving (either literally or just as a measurement of events?) as it passes the sun?

One theory is that it is caused by universal expansion:

"This acceleration can only result from the linear expansion of the matter comprising the earth. It is this universal expansion of matter that is the

simple and local cause of gravity.

.....It is this constant upward velocity at the surface of matter that is the universal constant for gravity." http://www.circlon.com/living-universe/015-cause-of-gravity.html

But it seems we are talking small amounts and for very fast moving things:

"The curvature of space alone has almost no effect on the movement of objects until they are moving really fast...the total stretching of space due to

the Earth amounts to less than 1cm."

Other scientists, while also admitting that they don't fully understand gravity, suggest that a greater understanding of dark matter will some day provide more clues:

"We think we understand gravity in most situations," he says "but when we look at galaxies and, on much larger scales, at galaxy clusters, we see

things happening that we don’t understand using our familiar equations, like Newton’s equation of gravity or even Einstein’s gravity. So we have to

assume there’s this mysterious form of matter, which we call dark matter, which we cannot see."

http://www.dailygalaxy.com/my_weblog/2013/11/our-understanding-of-gravity-is-fundamentally-wrong-two-conflicting-theories-of-the-universe.html

So no, I am guessing that few scientists would claim that Einstein's theory of GR gives a complete picture of gravity.

Space-time is the co-ordinate map that we use to model the universe.

It is akin to a flat Cartesian map of the Earth as opposed to a globe map, such that the points on the far right side identify with the points on the far left. If you go off the right hand side of the map, you re-appear on the left. This is called intrinsic curvature, it is not embedded in a higher dimension.

The globe map on the other hand, has what's normally considered 'curvature', as you have to circumnavigate around the globe to get to the other side.

This is called extrinsic curvature, and requires an embedding dimension.

Mike you keep asking " Is there something tangible 'there' ? "

And people keep telling you "No".

Yet you cannot accept that, and keep repeating the question.

I don't think this is getting any of us anywhere and its time you started adjusting your thinking regarding this requirement to have something tangible.

 

It seems that you are suggesting that we shouldn't search for something tangible about spacetime (with its own brand of 'curvature') because, unlike the tangible earth (which is perhaps just mass/energy anyway), there is no higher dimension for the universe. However, the fact that there may be no higher dimension in itself does not negate the possibility that spacetime is, if not as tangible as a spade, something more than nothing (particularly given its specific 'qualities' such as gravity, time dilation, and curvature). Indeed, could one not suggest that the backdrop of the multiverse (that some physicists propose) provides such a higher dimension? However, I do take the point that space-time is a sort of trade off and that this has something to do with gravity (with the role of mass seeming less clear). Indeed, it is amazing that math of Relativity fits 'reality' so well, as Einstein himself quipped, given that, in his own case, he penciled the math all out in his room in a couple of weeks without any particular appeal to data or empirical verification (while his poor wife was instructed to leave him alone except to leave his food on a tray outside his door).

 

But no, it would be nice to understand a little bit more about the "why" of spacetime than just that we can map it out....that does not mean that one wants to understand it in such a literally "tangible" manner that one can see or touch it.

 

Personally, I don't think that there is anything wrong with being Socratically persistent in pursuing a question. Of course, it is good to rephrase the question or perhaps give an illustration or to suggest possible answers, etc. Whether people want to continue to explain or not is up to them. Indeed, Einstein stated that he asked some pretty simple questions about the nature of light for years in order to galvanize his thinking, despite the fact that few if any could give him any answers at all. Also, I don't think one should ever give up trying to explain things in different ways to people who have different types of intelligence (in accordance with multiple intelligence theory). Even if images are misleading in some respects, such as spheres rolling around on the net of space time (even though the spheres are a part of spacetime themselves), they can be an immense comfort and initial help to those who are not particularly mathematically minded, such as myself.

 

 

 

I think a key question is whether nature really does abhor a vacuum (apart from the mathematical speculations) so that one does not know whether time exists in a vacuum in pure spacetime without matter. Since Einstein predicted that we'd be able to tell gravity was present during those early moments, thanks to gravitational waves (or changes in a gravitational field), I wonder whether, just as you can't have one without the other when it comes to love and marriage according to the old pop song, you can't have time without space as well as, perhaps, gravity and matter. If so, perhaps one can't say whether one is more basic or precedes the other, or whether they are all inevitably interwoven as one.

Relevant quotes:

"if the universe can't curve (because gravity doesn't exist), then there can be no matter or energy within it."

http://www.livescience.com/17809-gravity.html

"The spacetime structure of the metric field is shaped by what it contains. This may mean that space and time would not exist if there were not matter or energy in the universe."

http://www.thestargarden.co.uk/General-relativity.html from Norton, J. D., 'The Hole Argument', Stanford Encyclopedia of Philosophy, last accessed 15-02-16.

What I do need to know in this instance is " what exactly ( in reality terms ) is Space or Space - Time that it can be bent or curved or what ever . Is it a field , if so what sort of field , grit field , rubber field , electromagnetic field . Atomic field ,

 

I agree that from a strictly semantic standpoint, the degree of "nothingness" that we presume that space (or should I say 'spacetime' ) has can not be very high if it contains properties such as time dilation and curvature, so that we intuitively assume that it must have a degree of "somethingness." If it is indeed, a field of some sort, as ones intuition seems to suggest, then it would seem that scientists either have not detected what sort of field it might be, or else categorically deny that it is a such a "spatial field" (for lack of a better term) that "is somehow involved with" the properties, directly or indirectly, associated with time dilation and curvature.

 

Similalry (I think), Lawrence Krauss remarked that there could not have been absolute nothingness originally, since there would not be the necessary ingredients for a Big Bang to take place if that were the case....that is, there was a sort of partial nothingess.

 

He also is quoted as stating that "If you removed all of the particles, all of the radiation, absolutely everything from space and all that remained was nothing, that nothing would weigh something."

 

Article on Krauss's views on multiverse and types of Nothingness: http://www.nytimes.com/2012/02/21/science/space/cosmologists-try-to-explain-a-universe-springing-from-nothing.html

 

 

 

Because they have energy-momentum. For ordinary bodies, their mass would be what makes up most of the contribution, but if they have a substantial amount of angular momentum or net electric charge, or if they carry a magnetic field, then that would play a role as well ( albeit a small one ). What's more, if the bodies have spatial extension ( i.e. if they can't be considered point-like ), then their shape and internal composition would also matter.

Amazing. So can I presume that mass, angular momentum, (angular velocity?), net electric charge, magnetic field, and spatial extension all have an effect on time as well as the 'curvature' of space?

Isn't angular velocity, or just velocity, also a factor?

To change topic a little, what seems odd to me is that everything in the spaceship, in effect, slows down, (though we say time dilates) in proportion to how fast the ship goes. This suggests to me that the faster all the molecules of the ship are traveling away from the twin on earth, the slower, in effect, that they are actually moving about as they go, e.g., the slower the DNA of an astronaut is replicating. Sounds like a contradiction. In any case, the twin on earth isn't really in some sort of inertial or stationary position as the earth is both turning at a rate of 1000 mph (at the equator), as well as around the sun at 67,500 miles an hour, as milling around the galaxy along with the sun at a rate of 43,000 mph towards the star Vega.

I suppose that these are not considered a factor in the twin paradox because they are so small in comparison with the hypothetical speed at which the spaceship is said to go in the thought experiment.

When viewed from 'far away' - as far as the person in the well nothing changes for his/her clocks. You only get time dilation effects when one compares clocks.

That seems like you are suggesting that the younger spaceship twin will only notice that his earthbound twin has more wrinkles when he gets back to earth and compares complexions. This suggests that they looked the same until they met up.

Or, the equivalent, that a person living near the dead sea will only notice that his twin living in the Himalayas has (slightly) more wrinkles (for arguments sake...I doubt any difference would be perceptible) when they meet up for the first time since childhood fifty years later. Again, this suggests that they looked the same until they met up.

Surely such ageing is real and continuous (e.g., during all the time that the twins were separated), and not just a matter of people observing time differently depending upon their frame of reference, or of their suddenly ageing when they meet up or compare clocks.

That is not what happens. Time dilation is a relationship between different clocks in spacetime, it is not a physical "change" of some sort that "happens" to a clock.

I have read something to the effect that "Clocks just tick slower in a deeper gravity well. Hearts beat slower. Synapses fire slower. Food is digested slower. Lungs extract air slower. Molecules move slower. DNA breaks down slower. Absolutely every single thing happens more slowly when in a deeper gravity well."

This was the sort of thing I am referring to when I suggested that "time" is just an umbrella term that describes how things "happen" more slowly in comparison with similar clocks or people elsewhere.

In short, it seems to me that "time" is synonymous with "happening." If the twin who returns in the spaceship really is younger than the one that stayed on earth when they shake hands, we can't just say that time dilation is a relative/observational phenomena....the aging is real.

I am wondering whether, in terms of the spacetime model, whether the word "time" itself is not misleading: Isn't the so-called "curvature" of space enough to explain the apparent time dilation effects that have been detected? For a lay person such as myself, one might ask whether time just "seems" to slow down under certain conditions (e.g., depending upon distance from earth) because everything in a clock slows down (not to mention the rate of cell divisions).

I have read a couple of places that photon clocks, unlike atomic clocks, are not affected by gravity or whatever with respect to time dilation....true or false?

Perhaps one might use the term "curved space" instead of "spacetime." Could we not also use a term such as "compression" to refer to the fact that things slow down in space, just as someone walks more slowly when in shallow water? Doesn't the term "compression" make more sense in terms of explaining how gravity is found everywhere on our spherical planet....seems hard to envisage space bending entirely around a sphere. Light bending as it passes the sun seems to be a pretty literal example of spacetime curvature....so then wondering why scientists say, no, the term "curvature" is just an expression that is used to explain the measurements, but shouldn't be taken in the usual sense of the word.

In general, I get the feeling that lay persons are less concerned with whether or not scientific models (e.g., Theory of relativity) come up with workable measurements, than they are with getting some sort of metaphor that will help them partially understand what seems counterintuitive and that can not be visually modeled. (As an aside, i recall reading that Einstein said when asked what might be unusual about the way he thought, he replied that he thought in terms of "more or less distinct visual images.")

"spacetime works without any process in it...time is still ticking away"

i think that this is rather speculative. Perhaps we can construct models that suggest that, but it is something of a fallacy to think that our models, however neat and tidy, must represent what is going on. I think that the claim that one fully understand time is as spurious as the claim that one understands quantum theory. I have have come across quite a few comments from various physicists on this question, and it seems that there are many different opinions, e.g., Kurt Godel or Sorli and Fiscaletti. It is one thing to say that "spacetime works without any process in it" with respect to a particular model of a universe, and quite another to make this statement as if it is an indisputable fact. This is hardly an open and shut case and I suggest the jury is still out with regards to speculations, for example, as to whether we can have space without anything in it, or whether there is such a thing as an absolute vacuum apart from theory, etc.

Not to mention that evolutionary theory in general rubs fundamentalists/literalists/creationists the wrong way, to say the least: Actually it brings their whole world view crumbling down like the walls of Jericho.

Strange. Keats? Perhaps a quote might be in order as I have no idea what you are referring to.

I have still seen no evidence that Freud used anything approaching science.

 

Freud kept track of the effect that various treatments had on patients. As I said, even evolutionary psychologists such as David Buss and David Schmidt who use rigorous scientific methods to validate their claims are often dismissed as being unscientific....so it is a matter of opinion as to just what constitutes science when dealing with the vagaries of psychology. I see no point in going around the mulberry bush any more on this issue.

 

We get a lot of people presenting their ... ahem ... "personal theories" of physics on these forums. They make various claims about what science will discover in future (based on no science at all). If some of those guesses turn out to be correct, it doesn't show that their theory had any scientific basis, just that they were lucky.

 

I don't follow. If said amateur physicists wrote extensively as to what they believed, and it turned out that their idea of, say causality were confirmed, I see no reason to derogate their rudimentary efforts. Indeed, one could say of many pioneers of science that they made a lot of blunders...they key idea is that they posed various questions and opened up various issues. Neuroscientists, for example, find correlative areas in the brain for Freud's theory that there is a biological basis for cognitive conflict, e.g., areas of the brain that, often without our being aware, conflict with and try to suppress other desires. I would say that Freud was making a pretty good educated guess with regards to many issues (e.g., the defense mechanisms have withstood the test of time and are standard tools in many a modern day therapists toolbox) given what was known at the time..I see no need to begrudgingly belittle people's insights, be they amateur physicists with pet theories or professionals starting up a new field.

 

All that neuroscience's confirmation of some of Freud's ideas shows is that you can learn something about human nature by (informally) looking at the way people behave. Not exactly surprising. And not evidence of him "doing science".

 

Again, I have acknowledged that his efforts to be scientific were compromised by the lack of information he had at the time as to how to conduct psychological research as well as his own professional-political agenda, so i don't know why you keep bringing that up. No, neuroscientists have done a lot more than just show that he looked at the way people behaved. In particular, they have shown parallels between his superego-ego-id construct and neuroscience, however valid or invalid such parallels might be, e.g., the evolutionary model of the triune brain. Sounds like you are just off handedly throwing out criticisms as if just shooting in the dark here without referring to anything specific in the literature.

 

I'm quite sure that many other common ideas about the mind have been confirmed by science. And I am certain that, like most of Freud's ideas, many popular ideas will have been shown to be misconceptions.

 

Perhaps you could elaborate on what "common ideas" you had in mind. Of course, Freud made many claims that we find inane today. But again, Freud's originality has made him one of the most influential thinkers of the century, so I think your efforts to summarily dismiss seem rather strange.

 

And I guess he would be disappointed to find that such studies, as well as those taking a scientific approach to psychology, show most of his ideas to be wrong.

 

No, but he seemed to be aware of which of his ideas would most likely be confirmed in the future.

 

You think I should approve of his methods because of his conclusions?

 

Again, didn't say that.

 

 

Strange states that, "even if religion has an origin in evolution/survival that is no reason to criticize it. That is like saying people shouldn't like music or fall in love because they have an evolutionary basis." And then, "It seems just as irrational to say they shouldn't have those beliefs as to say someone shouldn't like a particular type of music."

I am with Memammal on this one. It is not a matter of saying that the they shouldn't have beliefs, but it does raise the issue as to whether the beliefs are valid. Pointing to the fact that something might have an evolutionary basis doesn't always or even very often suggest that it is not valid. It has been argued, for example, that the fear of snakes and spiders has evolved because those who avoided them in general, avoided the poisonous ones, and lived to pass on what eventually became an instinct...and the instinct is valid, despite being, in practice, rather indiscriminate.

But religion is, I think, an unusual case. Religious people are generally unwilling (rightly or wrongly) to accept the notion that the desire to believe in god(s), for example, is just an instinctive desire to feel protected. (E.g. evolutionary psychologists, building on Freud's concept of religion as a projection of ones parents, argue that women tend to be more actively religious because they feel generally more vulnerable than men, particularly if pregnant perhaps, and thus, create an imaginary figure of a protective god to help them get through life). Thus, you can see that a religious person would be reluctant to reject such an explanation, because it basically tends to reduce religion in general, and a person's faith in particular to nothing more than wishful thinking (though evolutionary psychologists don't generally come right out and say that).

However, if you tell a drummer that his or her skills are based on evolved instincts (e.g., in relation to mating, hunting, or weather controlling rituals) that go back thousands of years, music is not depreciated at all. It is still as moving, if not moreso, than ever.