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Posts posted by Sisyphus

  1. How do you know that matter-energy receding away from each other faster than the SOL won't curve around and reappear on new horizons of each other?


    Recession is not motion, so that's impossible no matter what shape the universe has.


    Not "simply in another universe." I said that the interior of a black hole could generate spacetime-expansion within its contents and that this could appear as a "big bang" of an independent universe from the perspective of an observer within that universe (assuming such an observer could/would be able to observe it).


    What mechanism are you suggesting for that? What is it that you mean by "the interior of a black hole?"


    Which energy? In what context? If the universe is prone to irreversible fragmentation into regions unreachable from one another (as you said earlier), in what sense could energy be infinite?


    Presumably, in the whole.


    How can gravity and mass cancel each other? Are you just talking about variable in an equation or are you actually proposing that there is some physical mechanism where gravity and mass can cancel each other somehow?


    Mass is positive energy. Gravitational field energy is negative. If the density of the two are equal, then the total density is zero, and they "cancel out."


    How can energy be infinite in any context if it is conserved in every context?


    Each expression of energy in a physical manifestation is a finite amount of energy. The only way it could be infinite is if it somehow multiplies itself under certain conditions, like if somehow unbeknowst to anyone the sun was multiplying energy and radiating it endlessly. How else could energy be infinite? You can't rely on the whole transcending the parts. If energy is conserved in every observable part of any imaginable universe, how could it be infinite on a grander level?


    It seems you're confusing "infinite" with "finite and endlessly increasing." That misunderstanding seems to be the basis for much of this thread, actually. Infinite does not mean increasing over time. It means right now, the amount is larger than any finite amount.

  2. Say you buy two new laptops. The first one is an ordinary laptop with nothing pre-installed. The second one is exactly similar but with many programmes preinstalled and downloaded (word processing, photos, music tracks, films, adobe, thesaurus etc). Both are switched on and in idle mode -no programmes actively running. If I had to choose which one had the most 'energy' inside, I would choose the second, even though they both use the same amount of electrical energy at that passive stage. The second one with the information in it has the potential to do stuff (a characteristic of energy). Energy does stuff, no energy equals uselessness i.e death.


    If you can't measure it in joules, it isn't "energy." End of story. That something happens to be more useful to you personally doesn't mean there is more energy present or vice versa (the laptop still works if you put in in the freezer, but not if you set it on fire!), and just because something takes more information to describe does not make it more useful or vice versa.


    In fact, if anything the opposite is true. Entropy doesn't change the total energy of a system, but it does decrease the useful capacity for work but tends to increase the information needed to describe it.

  3. What you mean is that probably, following Pythagorean logic, Minkowski made a first try with plus signs everywhere and saw that something was not corresponding to reality. Putting a minus sign solved the problem, and that's it?


    No. The following link is an excerpt from Einstein's own book explaining relativity to the layperson. It's a derivation of that equation.



  4. I'm having trouble understanding what "competing goods" means in the context of this discussion. Surely conflicts between "good" ends are a consequence of circumstance. But doesn't an omnipotent being create its own circumstance, by definition?

  5. It is unlikely to be infinite...


    Says who?


    Why is there no outside? No edge? How about a surface?


    Because the universe, by definition, is everything that exists. An edge is a boundary between things inside and things outside.


    And why would you end up back where you started if you were travelling through space?


    Because that's its shape. The same reason if you travel in a straight line on the surface of the Earth, you end up back where you started.


    Gives me the names of your centre-less shapes...


    Some of the various possibilities are given here:



    The example I gave, the 3D analog to the 2D surface of a sphere, is called a3-sphere.


    [Many things form spheres in space so it too may be spherical. As it is spreading out equally in all directions it is likely to be a spherical shape IMO.]


    It is not spreading out through space, though. That's the whole point of this.


    You can use flying equipment to leave the surface of a planet...Why no a special kind of space-ship to leave the universe.


    In order to leave the surface of the planet, you have to enter the third spatial dimension. To similarly "leave" the universe, you would have to enter a 4th spatial dimension. There is no direction in space that will lead you out, just like you can't leave the Earth by walking.

  6. First off, you need to stop the ad hominems, right now. "Only potheads support legalization." "No intelligent people support legalization." These are logical fallacies, and are against our rules.


    Second, your hypothesis is incorrect: I don't smoke marijuana at all, and I fully support legalization. Is it only people with alcoholism who support the 21st Amendment?


    What you're doing is making a circular argument. You basically seem to be saying that it is illegal because it is wrong, and it is wrong because it is illegal.


    And I'm not saying that marijuana isn't harmful. It isn't nearly as harmful as many things which are legal, like alcohol, but that isn't the point. Eating cheeseburgers is bad for you, too. You say there is no reason for marijuana to be legalized. Ok, what is the reason for cheeseburgers to be legalized? How about in a free country, you don't need a good reason for something to be legal?


    Beyond that, the prohibition of marijuana is extremely expensive and laughably ineffective. Everyone who wants it can already get it. All prohibition accomplishes is making the product less safe, funding organized crime, and putting a whole lot of otherwise law abiding and productive members of society behind bars for something about as harmful to society as drinking a glass of wine. All of the same reasons the prohibition of alcohol in the 1920s was a bad idea also apply to marijuana.

  7. Well now it's time to answer the title question...The universe must have a centre...In order for it to not have a centre it must either be infinite [which it is not]


    We don't know that it isn't infinite.


    or doughnut/bagel shaped...but that would mean that the universe has a hollow centre and therefore still has one.


    That isn't true. You can't think of the shape of the universe as some 3D object (like a donut) inside a larger space, because we're talking about the shape of space itself. In other words, that "hollow center" is part of the universe, too. There is no "outside," and there are no edges.


    However, there are plenty of finite shapes with a finite volume but no center or edges. These aren't very difficult to describe mathematically, but can be very difficult to imagine if you're not used to it, as is the whole concept of curved space.


    One example is a universe where if you travel in a straight line in any direction, you will eventually get back to where you started. This is similar to how if you walk in a straight line on the surface of a planet, you'll eventually get back to where you started, except the surface of a planet is 2 dimensions, and space is 3.

  8. I'm sure I have read that various forms of incest were the norm among the ruling class of ancient Egypt. I think it is generally believed that this led to various genetically based problems - both physical and mental. It seems therefore a good idea for any government to discourage this activity.


    It's the norm among the ruling class of Europe, also. The geneologies of the various royal families (or really royal family, since they're all related) include a huge number of first cousin and uncle-niece marriages. Here's a quote from Wikipedia about Charles II of Spain:


    The most famous example of a genetic disorder aggravated by royal family intermarriage was the House of Habsburg, which inmarried particularly often. Famous in this case is the Habsburger (Unter) Lippe (Habsburg jaw/Habsburg lip/"Austrian lip"), typical for many Habsburg relatives over a period of six centuries.[22] The condition progressed through the generations to the point that the last of the Spanish Habsburgs, Charles II of Spain, could not properly chew his food.[23] (See mandibular prognathism.)


    Besides the jaw deformity, Charles II also had a huge number of other genetic physical, intellectual, sexual, and emotional problems. It is speculated that the simultaneous occurrence in Charles II of two different genetic disorders: combined pituitary hormone deficiency and distal renal tubular acidosis could explain most of the complex clinical profile of this king, including his impotence/infertility which in last instance led to the extinction of the dynasty.[24]


    And when you look at his family tree, it's not surprising:




    Despite all that, I don't really understand why it's illegal, given how firmly we as a society are against all other forms of eugenics. And honestly, I think if it were legal, it would still be so uncommon as to have negligible effect on society as a whole. The only real justification I can think of is that it could be considered "child abuse" merely to bring an incest baby to term, but again, we're hardly consistent as far as that goes, since in no other instance is it illegal to conceive a child that it is known will be prone to genetic disorders.

  9. ...If we don't have all the answers yet, why is Steven Hawking wasting his time? [in trying to create a theory of everything.] He should be trying to find the missing answers...

    Topic closed methinks...[if there is no answer there is no point in me asking the question until someone finds the answer]


    If we already had all the answers, people like Stephen Hawking would be out of a job.


    Also, I said we don't have complete answers, not that we don't have any idea. (I also said I didn't really personally understand it.) Here's a quote from the Wikipedia article on metric expansion:


    Until the theoretical developments in the 1980s no one had an explanation for why this seemed to be the case, but with the development of models of cosmic inflation, the expansion of the universe became a general feature resulting from vacuum decay. Accordingly, the question "why is the universe expanding?" is now answered by understanding the details of the inflation decay process which occurred in the first 10−32 seconds of the existence of our universe. It is suggested that in this time the metric itself changed exponentially, causing space to change from smaller than an atom to around 100 million light years across.
  10. That melodramatically xenophobic video is ridiculous for a whole host of reasons, but let's start with:


    1) Islam is not genetic, it's a belief system. All four of my grandparents were devout Christians. I am not. Perhaps there will be a larger proportion of people descended from Muslims. That does not mean there will be a larger proportion of Muslims.


    2) Current trends are just that: current. It is illogical to assume that current birth rates will remain the same, since they have changed constantly in the past. My prediction is that as the Islamic world becomes wealthier and more stable, it will also become more liberal/secular and birth rates will decline, just like they did in "Christendom." Birth rates have a strong inverse correlation with prosperity and quality of life.

  11. No, Sir. You did not answer any of my doubts.


    I will be satisfied if you will clear my one doubt as given in my last post: Why are spring tides, both at opposition (when sun and moon are on opposite sides of earth) and at conjunction (when sun and moon are on the same side of earth) are equal?


    Tides are symmetrical - the bulge is on the near side as the attractor as well as the far side. (The near ocean is attracted more than the center, and the center is attracted more than the far ocean.) Two attractors on opposite sides will therefore add together the same as if they were on the same side.



    @Sisyphus: If there is more space...where did it come from?...


    Space is just the distances between objects. It doesn't have to come from anywhere. If you mean "why is it expanding," then that's a pretty complicated question that we still don't have a complete answer to, and which I don't particularly understand myself.


    and planets can move through space...they aren't fixed like dots on a bloon.


    Why does that matter? If you want, use ants walking around on it instead of dots drawn on it.


    It's not supposed to be a perfect analogy for the actual universe. Just a way to get at the concept of getting farther apart without moving.

  13. well, if we are on the topic of theoretical physics, we cant just say that the universe in infinite is size, when theoretically, it could be curved around itself. We could all be living a giant "hyperdonut". In this case, there definitely would be a finite size of the universe, there still would be no "endpoints", but it is still finite none-the-less, and you would not be able to fit an infinite amount of energy inside of it.


    I didn't say it's infinite in size. I said if it's infinite in size, which.

  14. Exactly what is in the title...


    I am confusion...How can it be possible for all galaxies to appear to move away from the one you are using as the point of view?


    Looking from one galaxy it appears that the others move away but if you use many as your point of view how can they all move away from each other?


    It isn't possible for them to move that way. However, the expansion of the universe is not motion through space. It is an increase of the amount of space.


    One common analogy is an inflating balloon with dots drawn on the surface. The surface area of the balloon represents space, the dots represent stars, galaxies, etc. As the balloon inflates, the surface area of the balloon increases, and the dots get farther apart. However, the dots are not changing position - there is just more and more "space" between them.


    If you universe began from a singularity how can it not have a centre...everything must have expanded from that singularity...therefore everything must be expanding evenly from 1 central point.


    The singularity would have been everywhere. It wouldn't be a point in space, it would be space, just with everything infinitely close together. Imagine instead the balloon is shrinking so that the dots get closer and closer together and the surface shrinks more and more, until finally it shrinks down to zero and there is zero distance between the dots. That is the singularity. It isn't a "where." It's a "when."

  15. Why is it that in one post someone claims that the position of electrons is unknowable and in another someone claims that the orbital shapes are defined?


    Because both are true. The shape of the wave is defined, but the position and momentum of its interactions are unknowable ahead of time. That's wave-particle duality for you.

  16. Thank you for good answering.

    But its not all sufficient for explaining gravity role in the Universe.

    Sloan Great Wall is not one galaxy.

    Why galaxy does not become huge amount of size beyond our imagination!!!

    According to our thought, Gravity is an attraction force, it can pull everything nearby without any trouble.

    There may be something we don't know.


    Our galaxy is huge beyond my imagination.

  17. lemur, orbitals and orbits are completely different things. If you must make an analogy to some classical situation, you'll be closer to the truth if you think of an electron as a standing wave instead of a little object zipping around. The orbital is just the shape of that standing wave.


    The reason only certain energy levels are "allowed" is just a mathematical consequence of their wave nature, similar to how it's only possible to have certain patterns of peaks and troughs on a vibrating drum.

  18. The more distant a galaxy, the greater the redshift. But is that really a vaild support for the expanding universe? The farther a galaxy is, its light will have to travel farther distances. The farther it has to travel, it will have a greater chances of interacting with atoms/molecules in space-as a result of the interaction, it will have less energy(thus resulting a red wavelength). So is the red shift really doppler effect or simply just the interaction of light?


    Just as a note, that redshift isn't the doppler effect. There are three kinds of redshift: doppler effect due to relative motion of the emitter and receiver, gravitational redshift from "climbing" out of a gravity well, and cosmological redshift, which is due to the expansion of space through which the light is traveling. It's the third which we talk about when we talk about the expanding universe.


    What you're suggesting is basically a "tired light" cosmology, which for various reasons have been discredited. I don't know a lot about it, but check out the "criticisms" section of the linked article, which lists some basic problems. Basically expansion successfully predicts a lot of observations that tired light does not (time dilation, ages of stars, etc.), and there are no known viable mechanisms for "tiring" light that would result in what we actually see.

  19. I think there's some confusion here. There aren't different kinds of energy, though we often speak that way. All energy is measured in joules, etc. Energy is also not a substance in itself - it is a property that other things have.


    There are, however, various ways energy is manifested that are useful to talk about. For example, it would be silly and impractical to talk about the individual and constantly changing kinetic energies of every atom in an object. However, we have a very useful and simple way to describe the macroscopic effect of the sum of those energies, and we call that temperature, or "thermal energy." You could, in theory, talk about every atom of steam in a piston and how each collides with the edges and on and on, or you can talk about the thermal energy being converted into mechanical energy, and everyone will understand what you mean.

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