SeekingToUnderstand

In the nomenclature of physics, is there a formal name for "light pressure" or "photon density"? losfomot, I don't know what you are referring to? Also is there a word for a vacuum that is not just that absence of atoms, but also the absence of photons? And does the technology exist to create such a vacuum? swansont, What are the names of the phenomena that use this effect?

Given that photons have a momentum, is there an analogy to atmospheric pressure that can be made - but in this case for light instead of for atmospheric atoms? If so, how strong or weak compared to atmospheric pressure would this "light pressure" be?

On a website regarding the physics of solar sailing, I read that "At Earth's distance from the sun, the solar flux, Ss, in space is about 1.4 kilowatts per square meter. This is enough power to run a hair dryer continuously, but not enough to power a car." I would like to know on the surface of the earth what an average range for the number of photons per cubic meter is? I know this is not the typical units of measurement for quantifying light in space. Any help is appreciated.

Suppose two spaceships originate at the same point on the x-axis and go in opposite directions, each moving at 0.8c. I would think that relative to one another either one would be moving at 1.6c. I know SR/GR states this is impossible. Why?

I sincerely appreciate all the help that everyone has provided in helping me to understand this subject matter. I believe I am finally beginning to get more of a grasp on it and it is the most bizarre theory. If it possible for a theory to be both correct and insane at the same time, then surely SR and GR meets the criteria. (assuming they are correct)

Cap'n Refsmmat, I certainly don't believe I am referring to the doppler effect.

Consider the twins paradox which states that one twin returns to earth actually being much younger than the other twin. When time actually slowed for the younger twin, what actually was occurring to the movement of the particles that compose him? Were the atoms jiggling slower compared to the twin on earth? I have no idea, but this is what I am trying to understand.

I really can't speak to the topic of atomic clocks, because they have the disadvantage that their mechanism is not apparent as it is with the ideal light clock. But with the light clock, by the very nature of the mechanism, the ticks will be less frequent from the arbitrary observer's point of view and the slower time is merely a definition of the clock itself.

In the case of an arbitrary observer looking at an ideal clock on a spaceship (composed of two mirrors, incrementing every time the same photon bounces back and forth), it is no mystery why the clock ticks slower. The light has to go a longer distance because it has a horizontal movement added to its vertical movement. As far as the arbitrary observer is concerned, a longer distance (lightpath) with a constant speed of light means the clock ticks slower.

There are many clocks that tick slowly. How do you decide when this means that time is moving slowly and how do you decide when this means that the clock is broken? In the context of the previous conversation regarding an arbitrary (randomly chosen) observer. If the observer has his own clock and sees that the clock on the spaceship is slow, shouldn't the observer come to the determination that the spaceship's clock is broken? And if the observer suspects that this is not a "typical" case of a broken clock, shouldn't the observer be able to look to the underlying mechanics of the clock to determine what is going on? Isn't it vital to be able to determine if a clock is only representative of itself or if it is representative of the system in which it is in. This is the deeper meaning of time that I am trying to understand and am asking for help in understanding.

Yes, as you stated, the arbitrary observer should have their set of the universe's position data generated according to their own clock - I didn't intend to suggest otherwise. So what exactly then is meant by SR and GR when it states that when an object moves fast relative to the arbitrarily observer, the arbitrary observer (who has his own valid clock) sees that the fast moving objects time has slowed down? To the arbitrary observer, his own time is the time, and the position of the fast moving object exists for each moment at his time. Does this mean the arbitrary observer views the fast moving object's atoms as jiggling slowly - would this mean the arbitrary observer would view the fast moving object as having a low thermal energy? Part of my difficulty in discussing the subject matter with clarity is that Einstein in my opinion really never gave a definition of time - to me, he basically sidestepped the issue by discussing clocks. Therefore, I am trying to understand the meaning of SR/GR when it states that the arbitrary observer sees a fast moving object as having slower time. To the arbitrary observer we have been discussing, his time using his clock is the time and the notion that he views an object of having a slower time is something I need clarification on.

md65536, I need to think about the cyclical reasoning, but regarding the Turing machine recording the state of the entire universe at a single time - yes this is definitely a fundamental part of the machine I am describing. Choose any observer's point of view (irregardless of whether one observer's view is any more correct than any other observer's point of view). For a randomly chosen observer, shouldn't there be a complete set of data describing the positional state of the universe because at that moment for that observer isn't his position compared to every other particle in the universe fixed, thus providing a complete positional data set for said observer. Philosophically restated, from the point of view of any observer (pick whatever one you want) doesn't the entire universe exist at once? If so, let this observer's position data about the universe be provided to the Turing machine for the current state. And if there is not a complete set of data for any particular observer, exactly what does this imply about the universe - doesn't the very idea of the existence of a universe for any given observer imply a complete data set for that observer?

swansont and anyone else who might be of assistance, I have been considering this point you make about the mathematical definitions that Cantor developed for comparing different types of infinity, specifically as it relates to line segments. In a deep sense, Cantor is correct that any two line segments have equivalent amounts of infinity, for if you zoom in or zoom out on a line segment, one can see that any line segment of any proposed length has the same internal relationships of all of its parts to itself (in this sense, when thinking about infinity in this relational way, the specific values for the endpoints are quite irrelevant and quite meaningless). However, if one does not have the option to zoom in or zoom out on the line segment, say because there is another line segment to be considered because both are measured in the same units. In this case, a line segment of length one clearly cannot contain an exactly equal amount of points as a line segment of length 10 (Since one could place the small line segment on top of the long line segment which necessitates a one-to-one mapping and the long line segment would still have a length of 9 which is not covered by the small segment). In the physical universe (which is not just a single line segment), but deals with line segments of a set unit and the relationship between line segments and everything else in the universe, I would argue that Cantor's notion of comparing infinity is not adequate. In physics, I believe the values of the end points of a line segment are crucial in comparing the number of data points contained therein explicitly because physics has the inherent practical purpose of comparing things in the universe. Just as the values of the end points matter, I would argue that the density of data points contained therein matter as well. So, if time slows for one object relative to another, then there cannot be pragmatic (for comparison in the physical universe) one-to-one mapping unless the second part of my proof holds true. And if one asks why it matters if there is a one-to-one mapping of data points (what does it matter if the object going slower in time has a null value for some data points), I would argue that the very ability of physics to make comparisons at a very fundamental level is attacked if one accepts null data. This is a very real shortcoming of Special and General Relativity because a primary goal of physics is to make comparisons at any level and an acceptance of null data muddies the waters in which to make those comparisons. In this sense, Special and General Relativity is at the very least contains major shortcomings (and at the most is simple incorrect).

Baryon, Swanson, and anyone else who will help, Alright, this is quite fascinating for me and I really appreciate your help. I accept the idea that there may indeed be infinite points in space and that it may be essentially possible to jump from one point to another (part 1 of the proof is flawed), but doesn't part 2 hold water anyways. If time is going slower for object A than for object B (because object A is moving fast relative to B), both of which are part of universe U, doesn't this mean that there must be positional data sets available for object B at which object A would be forced to have either null values or sequentially the same values? And aren't the inherent contradictions of both of these possibilities, that object A either does not exist (contradiction is object A does exist) or object A is not moving (contradiction is that object A is moving fast relative to B which is why it's time is slower) still proof that Special and General Relativity are incorrect?

I am lost. What is a false dilemma? Also, I thought you were suggesting that that if you need to get to points in a sequential order along a line was the part of the initial assumption that was wrong. What part is wrong?

Swansont, So then, are points on a line accessed in a non-sequential manner by someone who is walking along the line?

Are we in a shared universe or are we each in our own universe? And if we are each in our own universe, if each of our perspectives can be both absolutely correct and yet completely different, then what are we to make of the very clear indications that we occupy the same universe - are we not to agree that two objects cannot occupy the same place in space? I read the first several parts of Einstein's paper on Special Relativity and as far as I can tell, my thought experiment involving the spheres and string is very comparable to the types of thought experiments Einstein discussed with rigid rods. Can you please explain in more detail why if the string that goes between and through the two spheres shortens in length, how this can not mean that the two spheres would need to have the length between them shorten (considering the string is a viewable physical representation of the distance between the two spheres). I feel like I sensed the slightest bit of hesitation in your previous reply when you qualified your answer with an "i think" at the end. I sincerely appreciate your patience in helping me to understand this. ydoaPs, My point was exactly that Xeno's paradox was incorrect - I was absolutely not saying it is correct. My point was a philosophical one relating to the physical universe and I am certainly not the first to point it out (I mentioned this so as not to claim like it was a new discovery or taking credit for something that was thought of long ago). All I was getting at was the idea that, at least as far as I can tell, the physical universe must consist of discrete units of space because otherwise motion would be impossible. That is assuming you need to get to points in a sequential order along a line, something I assume implicitly - if the line contains infinite points, one can't get very far (technically nowhere) because you need to get between here and there first (a recursive notion that goes on forever). This is why I argue that surely the concept of a line as one made of continuous and infinitely many points could not be a proper representation of the physical universe and therefore that space must consist of discrete units. Regarding the topic of calculus or any other field of mathematics, just because a math can be formulated that is intrinsically consistent and correct does not mean that actually is an exact description of our physical universe. Rocket, notice that in your proof you suggest that you start out walking at a pace. If you assume you are walking at a pace, then you are already covering distance and the discussion of how to travel between two points is mute because you already assumed this traveling is possible in the first place simply by providing a pace. I am not an advocate of Xeno's paradox - it certainly does not apply to our physical universe as can be evidenced simply by moving in space. My point is that if our physical universe was constructed of lines in which every line segment has an infinite number of points between them, then Xeno's paradox would apply. The fact that we can move is a philosophical proof that the physical universe must consist of discrete units of space (regardless of how very tiny they are and regardless of how for most practical purposes we can simply consider that for most typical purposes, the concept of a line as described in Euclidean Geometry is all that is needed to perform calculations in physics)

Cap'n Refsmmat, I am very confused about whether relativity states that space just appears shortened or if space actually is shortened. In general I am very confused about relativity is saying how things appear or whether there is an actual change. In my example with the spheres, if from the perspective of the sphere the length of the string shortens immensely, given that the string goes from one sphere to the other, wouldn't that mean that the spheres must also perceive the space between them as having shortened (given that the string is the physical representation of this space). In the twins paradox, the information I have seen states that for the one twin going fast time really does slowdown which is why when he returns to earth he is younger than the other twin. Is relativity dealing with perception or reality? For anyone who is willing to help me understand this, I really appreciate it. I did not come here with an axe to grind - I came here to learn. What I wrote in my "proof" and the following discussion is simply my current understanding. I am asking for help in understanding where I have gone wrong. I sincerely want to learn and did not come here with an assumption that I am right - I just don't get it and am hoping to see where my flaws in thinking about the subject matter are. Thank you for your help, David To the others that replied, Please note my response to Cap'n. I didn't come here with a notion that I am right. I sincerely want to learn. I just thought the best way to do this would to show my current state of thinking about the subject matter and asking for clarifications on where my reasoning has gone astray. Please understand that I did not come here with an intent to teach, but rather than an intent to learn. Regarding Xeno's paradox, can you please explain to me how it would be possible to get anywhere in the physical universe if you had to progress across a continuous line. To my viewpoint, if this were the case, then Xeno would be correct and getting from point A to point B would be impossible because you would always have to get half-way there first. I took this to mean that since we clearly do move in space that space must be made up of discrete "units." Where have I gone wrong?

(very rough draft, interested in feedback, just wanted to get these ideas out there) A Formal Proof that the Theories of Both Special and General Relativity Are Incorrect followed by A Comparison of a Turing Machine to the Physical Universe, The Human Concept of Time, and a Critique of Special and General Relativity by David Ephraim Formal Proof: Part 1 (the argument here is nothing new but sets the context for Part 2): The physical universe must consist of discrete space increments because otherwise, according to Xeno's paradoxes, movement would be impossible. To reiterate, the physical universe is not continuous in the Euclidean sense because if it were movement would be impossible. Part 2: Consider the set U, representing the universe, which is composed of the position data of every particle in the universe. Consider the set O, representing an object in the universe, which is a subset of U. If O is moving very fast relative to other parts of U, then according to the theories of both Special and General Relativity, the time that O experiences must slow down. Given that O is a subset of U, the position data that composes O must be contained in U. Since parts of U will be experiencing fast time compared to O, there will need to be position data for O available even though this position data is being generated at faster rates for different parts of U. In order for O's time to be going slower and in order for O to be a subset of the position data available in U, the position data for O would either need to be null or it would need to sequentially have the same values as other data in U changes due to the differences in the speed of time. If the position data is null, then the object O would not exist which is a contradiction because by definition object O does exist. If the position data is sequentially the same then object O must not be moving which is a contradiction because object O is moving very fast. Thus, by reason of contradiction, Special and General Relativity are an incorrect description of the physical universe. Discussion: Imagine observing two theoretical universes. In the first universe, there is no correlation between anything. Observations yield no rules, nothing is predictable, and one moment is totally unconnected to the next. In the second universe, observations yield correlations between aspects of the universe . Predictions can be made and rules can be formulated to describe the universe. From the viewpoint of computer science, the second universe can be considered as a progression of data sets* which can be analyzed to find rules that govern the relationships between these data sets. Physicists have no contribution to make in the first universe. However, in the second universe, where the progression of observable data follows rules (which would be described as algorithms in computer science), physicists are delighted because they have an important role to play. The various rules (aka algorithms) that dictate the progression of the second universe can be compiled and a theory of everything (from the view of computer science, this can be considered a program that operates on the data sets presented by the universe) in the second universe can be established. Consider that in a very broad sense our physical universe, which is comparable to the second theoretical universe, can be viewed as a computation. Further consider that the simplicity of a Turing machine, which can perform any computation, can help to clarify the fundamental properties necessary to describe the physical universe. Generally, a Turing machine can be summarized with the following parts: there is an array (the physical universe's equivalent of position), there is a set of symbols (the physical universe's equivalent of fundamental particles), there is a state of the machine (the physical universe's equivalent of the positions of all particles in space) and there are rules to be applied (which can be thought of as the laws that physics seeks to learn about the physical universe) which move the machine from one state to the next (the following positions in space of all particles in the physical universe). Importantly for this conversation, the closest thing there is to time in a Turing machine is the application of next. There are no rules for the "pace" at which next needs to be applied - the results of the Turing machine will always be the same. This should help to clarify that for physics to describe the physical universe, time need not be considered a fundamental property. Indeed, the physical universe can be viewed as a change of states due to the application of the next function independent of the human concept of time. The human concept of time is based upon the relation of observed data to each other (i.e. the position of an hour hand in relation to the position of the sun, etc.). Without the relationships between this observable data, the human concept of time would be meaningless. Furthermore, when considering a Turing machine or the physical universe, the relationship between this observable data is created without any need for time to be a fundamental principle. Instead of the human concept of time, a fundamental property that is necessary to describe the physical universe is sequential observable data. Given that the human concept of time is not a fundamental property of the physical universe, the Theory of Special Relativity and the Theory of General Relativity are inherently flawed. Consider what would happen to the data set that represents an object moving in space at a very fast velocity such that "time" would have to slow down relative to other objects in space which are experiencing "faster time". Either the data set that represents the slowed down object would have to have null values (i.e. it would cease to exist) or it must have a sequence of the same values (i.e. the object would not be moving at all). Since, by definition, the very fast moving object cannot cease to exist and since it is moving very fast, it is impossible that it is not moving at all. Consider the following thought experiment which will show the inherently flawed contradictions that arise from the concept of length contraction. Suppose two massive spheres are separated by a vast distance. They have a narrow whole drilled through their cores and the wholes are linearly aligned such that a very long string can be pulled through both simultaneously. Further suppose that the string has length increments marked across its entire length. Suppose the string is pulled such that it reaches a very fast velocity - say 99.5% the speed of light. According to the theory of Special Relativity, due to length contraction the space that the string occupies between the two celestial bodies will contract immensely. But this implies that the length between the two celestial bodies would contract immensely. This is quite patently absurd. Given that one can imagine strings of different masses in this thought experiment, the force that needs to be applied to reach 99.5% the velocity of light can vary - and yet somehow any string moving fast enough can contract space and thereby pull the two celestial objects together. Einsteinian Relativity was conceived in an attempt to reconcile Gauss's equations with Classical Relativity. Philosophically, there is no logical reason that it must be possible to apply Classical Relativity to a massively smaller scale such as photons. Philosophically, just because it would be convenient from the view of formulating universal physical laws if our observations of data at one scale applied to all scales does not make it true.