Select Page
Poker Forum
Over 1,286,000 Posts!
Poker ForumFTR Community

**Ask a monkey a physics question thread**

Page 20 of 30 FirstFirst ... 101819202122 ... LastLast
Results 1,426 to 1,500 of 2239
  1. #1426
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by Poopadoop View Post
    right foot is gas or velocirator or whatever people call it here.
    It's definitely controlling the angular acceleration of the engine, which is equivalent to controlling the linear acceleration of the car, given the drive train is not switching gears. It increases the fuel-air flow into the cylinders (and some other things to facilitate this), which increases the force delivered per engine cycle, which increases the acceleration, 'cause F = ma.

    It can seem like you're controlling the velocity of the car with that pedal, because it's easy to forget that the wind resistance accelerating your car in the opposite direction increases with the square of velocity. When you increase your forward acceleration, the backward acceleration increases, too, so you reach a "terminal velocity" rather than keep increasing in velocity.

    What it's called may not be relevant to the physics, though.
  2. #1427
    http://www.hampshiredome.com/club/sc...?NS=FAQ&DN=FAQ

    ^So this thing collapsed this week. 20 inches a snow and pffffffft.

    What brilliant branch of physics came up with the idea that giant balloons make good buildings?
  3. #1428
    So they drive on the left, but the accelerator is still on the right? Fucking weird.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  4. #1429
    That's cool.

    Back to the laces though. What actually happens, physically, that would cause a knot to come undone? I can imagine there being two things: First, physical pushing and pulling which might happen if (e.g.) the arch of the foot were pushing against the laces. Second, vibration which might happen when (e.g.) the foot hits the ground on each step.

    Similarly, what are the qualities, physically, that makes a knot resistant to these forces and stay done up? Is it the friction between the laces of a tight knot that does it?
  5. #1430
    Quote Originally Posted by Poopadoop View Post
    physical pushing and pulling which might happen if (e.g.) the arch of the foot were pushing against the laces.
    You mean like the flexing of a foot operating a gas pedal?
    Quote Originally Posted by Poopadoop View Post
    vibration which might happen when (e.g.) the foot hits the ground on each step.
    or maybe vibrations caused by being in contact with something attached to a running engine?
    Quote Originally Posted by Poopadoop View Post
    Similarly, what are the qualities, physically, that makes a knot resistant to these forces and stay done up?
    Even I know that one!
    Quote Originally Posted by Poopadoop View Post
    Is it the friction between the laces of a tight knot that does it?
    Yeah
  6. #1431
    What actually happens, physically, that would cause a knot to come undone?
    I would have thought there are two main culrpits... vibration, and tension... and both will be overcome by not tying a slack knot. Where the knot is slack, the vibrations/tension allows motion of the lace.

    When you tie a knot, after letting go of the lace, you might note the knot will slacken a touch if it's loose enough. For example, I just tied up my dressing gown belt, and immediately after letting go, it undoes slightly and is a touch more comfortable than when I first pulled it. That's not my breathing, or air movement. That's tension and would happen if there were no other factors at play. Once the tension of the belt reaches equilibrium, it will no longer slacken. The eqilibrium in question is affected by the geometry of the knot... the tighter it is, the less space there is for movement. Ideally, the loop is exactly the same size as the thread going through it. And yes, I think friction is the reason that under such circumstance, there is no motion.

    This is all a guess though.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  7. #1432
    Quote Originally Posted by OngBonga View Post
    So they drive on the left, but the accelerator is still on the right? Fucking weird.
    It's all pretty arbitary and thus irrelevant which side the gas pedal is on. If pushing the right pedal made your car go left I could see this being a problem.
  8. #1433
    Quote Originally Posted by BananaStand View Post
    You mean like the flexing of a foot operating a gas pedal?
    Or walking or just about anything that involves moving the foot.

    Point is, if you tie a proper knot this shouldn't be enough to loosen it. Many people drive for a living. Go to a truck stop and see how many of them are walking around with their right laces undone.
  9. #1434
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by BananaStand View Post
    What brilliant branch of physics came up with the idea that giant balloons make good buildings?
    That would be civil engineering.

    David H. Geiger invented the air-supported structure.
  10. #1435
    Quote Originally Posted by BananaStand View Post

    or maybe vibrations caused by being in contact with something attached to a running engine?
    So you hold your left foot in the air while you drive? Cause the floorboards are probably getting the same amount of vibration as the gas pedal.

    maybe your gas pedal is loose and vibrates more though. dunno.
  11. #1436
    Quote Originally Posted by OngBonga View Post
    I would have thought there are two main culrpits... vibration, and tension... and both will be overcome by not tying a slack knot. Where the knot is slack, the vibrations/tension allows motion of the lace.
    Good point about the tension. I'm guessing that has something to do with the elasticity of the laces. So when you pull it tight you stretch the lace, then it springs back.


    Quote Originally Posted by OngBonga View Post
    I just tied up my dressing gown belt.
    I like the idea that it's past noon and you're still in your getting out of bed clothes.
  12. #1437
    For some knots it must also be the case that outside push/pull forces work to loosen one part of the knot but tighten the other, making the knot thus more resistant to loosening.
  13. #1438
    We need an experiment where Banana puts each foot on a vibrating plate and times how long it takes for the laces to come undone. If those times are statistically indistinguishable then it's not the tying that's the issue. If the time is less for the right vs. left foot, then tying is the problem.

    Get to work banana. You'll need to do a lot of trials for each foot so we get some reliable data.
  14. #1439
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    I strongly suspect that the driving / gas pedal is a red herring.

    My foremost hypothesis has not been directly refuted yet, so I'm not sure if I should drop it or not.
    I.e. are you 100% certain that you're tying square knots and not granny knots?

    ***
    There are many knots and they serve different purposes.
    Some have moving or slippery parts and stationary or fixed parts, yes. A slipknot has a loose part that forms the actual loop, and a fixed part which holds the loop closed.
  15. #1440
    Quote Originally Posted by MadMojoMonkey View Post
    I.e. are you 100% certain that you're tying square knots and not granny knots?
    I make an x, loop one end through the bottom of the x and pull.

    Then I make two bunny ears. I make an X with bunny ears, loop one through the bottom and pull
  16. #1441
    Quote Originally Posted by MadMojoMonkey View Post

    My foremost hypothesis has not been directly refuted yet, so I'm not sure if I should drop it or not.
    I.e. are you 100% certain that you're tying square knots and not granny knots?
    I thought you just finished telling me this wasn't your hypothesis?

    Also, the hypothesis assumes he's tying two different knots in the left and right shoe, so you're asking the wrong question Mr. Science.

    Banana, do you tie the knots with the exact same steps in each shoe?
  17. #1442
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by Poopadoop View Post
    I thought you just finished telling me this wasn't your hypothesis?

    Also, the hypothesis assumes he's tying two different knots in the left and right shoe, so you're asking the wrong question Mr. Science.

    Banana, do you tie the knots with the exact same steps in each shoe?
    Well... I am still not directly hypothesizing that he's tying 2 different knots, but you have made an excellent point.

    I was opining that he was tying granny knots on both shoes, and that they are more likely to slip. That completely ignores the issue that only one is consistently coming untied, which implies that my question is still moot unless I'm suggesting he's tying 2 different knots, which I'm not.

    Fair play. Good observation. My bad.
    Thanks for catching it.
  18. #1443
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by BananaStand View Post
    I make an x, loop one end through the bottom of the x and pull.

    Then I make two bunny ears. I make an X with bunny ears, loop one through the bottom and pull
    If you go right-over-left on the x, then go left-over-right on the X, that's a square knot.
    Also if you do those in reverse order.

    If you repeat the same thing twice, it is a granny knot.
    I.e. if you go right-over-left on the x and the X, or left-over-right on the x and the X, then granny.

    (lol, an alternate name for a granny knot is a lubber knot. I'm guessing as in land lubber. This knot is only known by insulting names. lol.)
  19. #1444
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by Poopadoop View Post
    You're saying a retard would do that with one shoe but replace the OVER movement with an UNDER movement on the other shoe? And then spend the next thirty-odd years wondering why one lace never stays tied up?
    I hypothesize this would be less likely in a retarded person than an otherwise intelligent person.

    'Cause the tactile feedback of doing something the same over and over is a reinforcing mechanism which requires conscious mental effort to change.

    Still... if someone, retarded or not, decided when they were first learning to tie their shoes (barely not a toddler), that there was some aesthetic preference to tie them differently, then that could go unnoticed by the conscious mind for ever. This for exactly the same reasons that it's so easy to tie them both the same always every time. Muscle memory was established and the subconscious deems the result "good enough to avoid re-inventing the process."

    Disclaimer: I'm not a psychologist or psychiatrist, and mostly distracting from the greater point, here 'cause I'm out of ideas, but still want to figure it out.
  20. #1445
    Quote Originally Posted by MadMojoMonkey View Post
    I hypothesize this would be less likely in a retarded person than an otherwise intelligent person.
    But it's a clearly noticeable difference in how it looks when you're doing it one way versus the other (at least to me). My point was mostly that someone who wasn't a tard would notice the correlation between doing things differently depending on the shoe and the one shoe's knot continuously coming undone.

    The fact that banana can't seem to answer the question about whether he does it the same way or differently for the two shoes suggests he is probably doing it the same and can't see a difference because there is none. Or possibly he is a tard and can't see it, but if so he is pretty articulate for a tard.


    Quote Originally Posted by MadMojoMonkey View Post
    'Cause the tactile feedback of doing something the same over and over is a reinforcing mechanism which requires conscious mental effort to change.
    Not sure what you mean by 'reinforcing'. Unless he gets a treat every time he does it the same way, the tactile feedback wouldn't have a reinforcing effect. It could theoretically be that he was reinforced by whoever taught him to tie his shoes to do it differently for each shoe ('good boy, have a banana'), in which case it is the teacher who created the problem.



    Quote Originally Posted by MadMojoMonkey View Post
    Still... if someone, retarded or not, decided when they were first learning to tie their shoes (barely not a toddler), that there was some aesthetic preference to tie them differently, then that could go unnoticed by the conscious mind for ever.
    Perhaps. But two issues arise here: First, we learn by being taught, so he would have had to have been taught to do it the correct way on one shoe and the incorrect way on the other. This would imply his teacher was a tard who was in turn taught by the tard method, and so on up the family tree.

    Second, he could have been taught properly but then made a mistake one day on one shoe and had his tying behavior continue in that direction from there on. It wouldn't be beyond a young kid to do that sort of thing. But iin that case my point above stands - they are visibly different methods, which shouldn't go unnoticed indefinitely.


    Quote Originally Posted by MadMojoMonkey View Post
    This for exactly the same reasons that it's so easy to tie them both the same always every time. Muscle memory was established and the subconscious deems the result "good enough to avoid re-inventing the process."
    Pretty much correct except it's the conscious mind deciding whether it's good enough or not, just like the conscious mind decided to make a post asking why it happens that one shoe comes undone more than the other.
  21. #1446
    Assuming the person ties the same knots on the left and right shoe, there's going to be differences in the postures of their two hands when they tie one shoe versus the other. These differences can range from subtle and probably inconsequential to large and possibly consequential.

    The degree of difference depends largely on the overall posture of the person, and to a lesser extent on the relative size of different parts of their body. Regarding posture, if they tie their shoes by sitting down and leaning over to tie each shoe the difference in posture is almost certainly not going to be large enough to have an effect. OTOH, if they tie them by crossing each leg over the other in turn, the differences in posture will be large and possibly make a difference. Further, in that example, the foot (and by proxy the shoe) will be prone to moving during the tying process, which can make it more difficult to tie a good knot.

    Regarding relative size of body parts, a person with long legs relative to the arms will generally have to adopt a more unusual posture when tying their shoes and thus be more prone to error.

    The brain works best when the joints are in the middle of their range because it gets the most accurate input from the position sense (the body telling the brain where its parts are, based on information from the muscle spindles, skin and joints). I vaguely remember learning the muscles can exert more force with the joints in the middle of their range as well - something to do with the stretch of the tendons or some such - but not sure if that would be relevant to tying one's shoes since it's more of a question of precision than force.

    Another issue could arise due to handedness. Everyone falls on a handedness continuum between strongly left- and strongly right-handed, with ambidextrous people in the middle. Counter-intuitively, the non-dominant hand tends to be the more precise one whereas the dominant hand tends to have more strength. In a movement where precision is key, being ambidextrous would be the ideal, and the further one is on the scale towards strongly left- or strongly right-handed the more likely the brain would have problems with executing precision movements with the dominant hand.
  22. #1447
    Another point is that since the shoes are mirror-images of each other, the habitual placement of the knot to one side of center could also have an effect that differs on each shoe. If you (say) put the knot right of center on both shoes and each foot experiences roughly a mirror image of the combination of forces the other foot experiences, that could (in theory) make a difference.
  23. #1448
    Holy shit you guys got a lot of mileage out of this
  24. #1449
    Quote Originally Posted by BananaStand View Post
    Holy shit you guys got a lot of mileage out of this

    I can get milage out of a conversation about how much milage we can get from inane conversations.
    Last edited by OngBonga; 03-17-2017 at 09:25 PM.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  25. #1450
    At extreme temperatures, such as those in the first few billionths of a second of the universe according to big bang, electromagnetism and the weak nuclear force are unified into the electrowaek force.

    The question begs... as the universe expands and cools further, would we not expect more forces to emerge as the forces we currently observe as one break down? If not, how can we be sure? And if so, would it be an abrupt change?

    Is superconductivity, ie zero electrical resistance, an example of different forces at super-cool temperatures?
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  26. #1451
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    The question begs... as the universe expands and cools further, would we not expect more forces to emerge as the forces we currently observe as one break down? If not, how can we be sure? And if so, would it be an abrupt change?
    I don't think so.
    We can be sure by looking at the current theory and seeing what it predicts about that temperature regime. We can do experiments where we cool things down to ludicrously low temperatures (many orders of magnitude colder than anything expected to be naturally occurring in the universe), and see what's up with them.

    Depending on your criteria, the lowest temp achieved by a lab is open to interpretation.
    Collections of sodium atoms have been cooled to 500 picoKelvin (1/2 a billionth of a degree C). These are miniscule in volume, but do exhibit an exotic form of matter called the Bose-Einstein condensate. This is predicted by the Standard Model of Particle Physics. This phase of matter may qualify under your hypothesis, but it's not likely to be a widespread state of matter in the universe on any timescale that I know of.

    Some solids have been cooled to a few milliKelvin. A 1m by 1m by 1m block of copper has been cooled such by an Italian group of researchers. I don't believe they discovered any new forces or any physics that isn't predicted by the Standard Model.


    If so, it would be an abrupt change. Anything which goes from a steady state of 0 to a non-0 is abrupt.

    Quote Originally Posted by OngBonga View Post
    Is superconductivity, ie zero electrical resistance, an example of different forces at super-cool temperatures?
    Kind of... they're different from the macroscopic world you and I find intuitive, but they're fully described by the Standard Model.

    Superconductivity is described in multiple ways, and I'm not sure if those ways are equivalent or if they're complimentary.
    I've gotten different information from different sources and it's not clear to me if either explanation is simplifying things so that I am less confused.

    One way is the formation of Cooper Pairs of electrons at cold temperatures. A spin-up and a spin-down electron can become entangled if their thermal energy is low enough to not break this bond as soon as it would have formed. This is essentially a new force which exists as the body cools. It was really there all along, but unable to express itself, due to the ambient energy density being so great that the pair would immediately dissociate if it formed in the first place, due to the bombardment of thermal particles all around.

    This is directly analogous to the early universe. The energy density was so high that at first no particles could form. Then only the lightest particles could form and interact via other light particles. As the universe expanded and cooled, gradually more and more particles were able to coalesce out of the maelstrom of energy and interact with other stuffs.

    The formation of the Cooper pair is remarkable, in that it takes 2 spin 1/2 particles (fermions - which obey the exclusion principle) and binds them into a spin 1 particle system (a boson, which does not follow the exclusion principle). So the individual electrons cannot be in the same state as other electrons, but the cooper pair certainly can. Weird.

    Another way that superconductivity happens is due to the uniform vibrations which happen in the crystal lattice against which the Cooper pairs are moving. Standing waves can set up in the body of the crystal, which change the nature of applied forces on the particles moving nearby.

    When superconductivity happens, I suspect there is a resonance between the phonons (quanta of lattice vibrational states) and the Cooper pairs. This resonance is such that these 2 systems don't express any forces on each other, hence the 0 resistance of a superconductor.


    EDIT: The bit in red is mostly wrong, and where it's not wrong, it's probably misleading.
    A better description is hinted at below, but when the energy density is high, particles can spontaneously come into existence, so there would be massive particles. My understanding is that with the energy density higher than the electroweak epoch, anything larger than a quark or gluon would be so instantly annihilated, so that only quarks and gluons existed in any notable %-age. I'm not sure what this means for photons.

    I understand this poorly at best, to be perfectly honest. I'll see what I can learn in the next few days.
    Last edited by MadMojoMonkey; 03-21-2017 at 07:50 PM.
  27. #1452
    Thanks for that detailed answer. I have another question...

    How did light behave in the electoweak world? What about before when the strong force (assumingly) unified with EW?
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  28. #1453
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Thanks for that detailed answer.


    Quote Originally Posted by OngBonga View Post
    I have another question...
    Keep 'em comin'.

    Quote Originally Posted by OngBonga View Post
    How did light behave in the electoweak world?
    Light is light. Photons are photons. They behaved the same then as now. They mediate the electromagnetic interactions. By mediate, I mean they are the exchange particles which express transfers of momentum. Changes in momentum over time are forces, recall. F = dp/dt, where F is force, dp is a small change in momentum, dt is a small change in time, and dp/dt is the incremental change in momentum over an incremental change in time.

    What changed is the W and Z bosons. They mediate the weak nuclear interactions. I'm not an expert on symmetry breaking, and that's what all the information on this topic cites. What I understand about symmetry breaking is that as things get colder, the randomness of the particles lessens, and patterns can emerge.
    E.g. Iron above the Curie temperature is non-magnetic, because the thermal motions of the particles make all the internal magnets align randomly. As the metal cools, the magnets' forces of interaction with each other are no longer dominated by the thermal forces of collisions, and the magnets begin to align. The rise of a permanent magnetic field as the Iron cools is a spontaneous symmetry breaking.

    I can speak to the reference in our discussion of thermal energy in the early universe. The rest mass of the W and Z bosons is 80 GeV/c^2 and 90 GeV/c^2. So when the average thermal energy of the universe was greater than ~100 GeV, these particles could spontaneously manifest themselves in the universe, so the population was insanely much higher than after this period (the electroweak epoch) ended. Of course, they were likely to get blasted apart by anything they interacted with, so they were popping in and out of the universe in a constant wash. Symmetry.

    I presume that weak interactions were commonplace during this epoch, that quarks were freely changing their "flavor" constantly, due to interactions with the proliferation of W and Z bosons about. This means that protons and neutrons weren't so stable, and probably that loads of exotic particles were more abundant.

    Once the average thermal energy of the universe cooled below ~80 MeV, W and Z bosons could no longer be spontaneously created from the background wash of energy in the universe, so they would have decayed in their normal time and the universe was basically the one we observe today, with 4 forces. Broken symmetry.

    Quote Originally Posted by OngBonga View Post
    What about before when the strong force (assumingly) unified with EW?
    This is entirely hypothetical. Grand Unified Theories happen prior to electroweak epoch, by necessity. It is not clear if any hypotheses accurately describe the universe prior to the electroweak epoch.

    Even the electroweak theory has some questionable parts, but mostly is solid theory. The existence of the W and Z bosons, as well as the Higgs, were predicted by electroweak theory prior to their observation. Once again, this is a hallmark of good science, and supplies great credibility to the theory.

    One part that is up for debate is when, exactly, the electroweak epoch happened. Some hypotheses place is as early as 10^-36 s after the big bang, while others place it at 10^-12 s after the big bang.

    As far as I understand it, the establishment of the credibility of the electroweak theory is why we believe the Standard Model is an accurate description (excellent approximation) of the universe from after the end of inflation up to now, and why we believe the laws of physics have been constant for at least that long.
    Last edited by MadMojoMonkey; 03-21-2017 at 07:39 PM.
  29. #1454
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    I edited the prior post in red to indicate where I did a poor job 'splaining things.
  30. #1455
    Quote Originally Posted by mojo
    What I understand about symmetry breaking is that as things get colder, the randomness of the particles lessens, and patterns can emerge.
    This has a name, doesn't it? Entropy?

    One part that is up for debate is when, exactly, the electroweak epoch happened. Some hypotheses place is as early as 10^-36 s after the big bang, while others place it at 10^-12 s after the big bang.
    This is why I was curious about the behaviour of light in the EW epoch. I mean honestly, it seems ludicrous to use the word "epoch" to refer to a period of time so infintesimal that we can't even begin to comprehend how quick that is to us. How far does light travel in that time? It's like the entire era that was the electroweak epoch had started and was over before light could travel a nanometer. I really can't get my head around how so much can happen in such a short amount of time. How many high energy collisions can a particle experience in a nanosecond in the most insanely dense environment one cannot even begin to imagine?

    My head is melting.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  31. #1456
    Quote Originally Posted by ong
    How many high energy collisions can a particle experience in a nanosecond in the most insanely dense environment one cannot even begin to imagine?
    oh snap

    Quote Originally Posted by mojo
    This is directly analogous to the early universe. The energy density was so high that at first no particles could form. Then only the lightest particles could form and interact via other light particles. As the universe expanded and cooled, gradually more and more particles were able to coalesce out of the maelstrom of energy and interact with other stuffs.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  32. #1457
    Light is light. Photons are photons. They behaved the same then as now. They mediate the electromagnetic interactions. By mediate, I mean they are the exchange particles which express transfers of momentum. Changes in momentum over time are forces, recall. F = dp/dt, where F is force, dp is a small change in momentum, dt is a small change in time, and dp/dt is the incremental change in momentum over an incremental change in time.
    Ok, but what I wanted to know is if light still travels at c in the EW universe. I don't think it will, but not because EM is different, rather because gravity will be truly immense.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  33. #1458
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Ok, but what I wanted to know is if light still travels at c in the EW universe. I don't think it will, but not because EM is different, rather because gravity will be truly immense.
    Light always travels at c. It even does so when the Index of Refraction is not exactly 1, but the QM is trickier to understand than the classical approximation of just assuming it moves slower by a factor of the IoR.

    Gravity doesn't change the speed of light, only the wavelength of the light.... and the stuff you know about directions and geodesics. Block holes don't trap light by slowing it down. They trap light by red-shifting it to the limit of infinite red shift, which has infinite wavelength, and therefore 0 energy. If it has 0 energy, it's not really a photon, it's been wholly absorbed by the black hole and its energy is converted to ... IDK... heat? It's a black hole... anything else it would be heat. With black holes, I'm not sure what heat means.
  34. #1459
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    oh snap
    I ninja edited that bit. I'm sure I don't understand it all, but I hypothesize it's like this:

    Symmetry
    The energy density is off the charts, so anything can pop into existence. BUT the energy density is so high that as soon as it exists, it's annihilated by other stuffs. It's a quantum mess of random sameyness all over everywhere.

    I wonder if the quark-gluon plasma idea doesn't all arise from quark confinement. Quarks are funny because the strong force holds them to each other and the strong force doesn't diminish with increasing distance like the other forces. Rather the opposite happens. The further apart 2 quarks are, the more strongly they attract each other. The gluons are the mediators of the strong force.

    If you try to pull a pair of quarks apart, eventually, the energy density in the gap pulling them back together creates new quarks, and you'll end up with (at least) 2 pairs of quarks when you started by pulling apart 1 pair of quarks. This isn't hypothetical, this is everyday stuff in a particle accelerator lab.

    So, in the early universe, quarks start popping into existence, but then the energy density bombards them, destroying some and forcing others apart, which creates more quarks, which are immediately bombarded, etc.


    ***
    Your comments on how far can a photon travel in such a short time span are cool.

    IDK. This is all quite removed from what I've studied.
  35. #1460
    That stuff about quark tension is cool.

    Light always travels at c
    So we're back to the problem of the entire life of the EW universe happening before light can travel even a tiny distance. That really does bend my head. Certainly, I feel like our concept of time is redundant in this world. I mean, the best I can imagine is that the universe is so dense, that even though a photon only travels a tiny distance in during the entire EW epoch, it still interacts with a truly massive amount of energy. I keep thinking of particles colliding, but I know we're at a much more quantum level than that. Still, it's a reasonable metaphor for what I can't understand going on, so forgive me if I persist with it. When we talk of time, we have to think of space, too. I think a light cone (actually a sphere) one light second in diameter would be a fair spacial representation of a second in time. This is the range of causality. A light cone with a diameter of 10^-43 light seconds is practically a singularity, yet an enormous amount of stuff must be happening in this region. From a tiny universe in a fraction of a second came the hugest and most complex of systems. It really does make you wonder what the fuck time really is.

    Time doesn't flow backwards, as far as we can observe. It flows at different rates for different observers, but always in the same direction. That reminds me of the second law of thermodynamics. Is time just the flow of entropy? Nature's eternal quest for equlibrium?
    Last edited by OngBonga; 03-21-2017 at 09:51 PM.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  36. #1461
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Dwell on the fact that there was (from memory) ~ a billion times more stuff in the universe back then. Matter and anti-matter were believed to be in near equilibrium for a brief while there. The exact mechanism for why only 1 kind of matter dominates the universe isn't known, but there are strong beliefs held by string theorists that there is a weak reaction which annihilates 10^-9 less matter than anti-matter... meaning that of all the mass in the early universe, only ~1 billionth remains.

    How that is not a singularity is not remotely known or credibly speculated.
  37. #1462
    I think the matter vs antimatter thing is really a simple question of probability. If we flip a coin 100 trillion trillion times, are we to expect there to be exactly 50 trillion trillion heads? The probability of that happening is actually very slim indeed. It's extremely likely that one side will very slightly dominate over 100 trillion trillion flips. The same happened with antimatter vs matter. There was perhaps 0.1% more matter, so it won. It actually seems fairly simple to me. The scary thing about this hypothesis though is that basically god was rolling dice when he made the universe, and a double six would've meant exactly 50-50 ratio, total annihilation, and no universe*.

    * as we know it
    Last edited by OngBonga; 03-22-2017 at 09:38 AM.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  38. #1463
    Quote Originally Posted by mojo
    Dwell on the fact that there was (from memory) ~ a billion times more stuff in the universe back then.
    meaning that of all the mass in the early universe, only ~1 billionth remains.
    But the energy still exists. It must do. What happened to that energy? The energy content of the universe is exctly the same today as it was 10^-43 seconds after big bang. And since energy is mass... well that "stuff" just changed, it didn't disappear.
    Last edited by OngBonga; 03-22-2017 at 09:36 AM.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  39. #1464
    How that is not a singularity is not remotely known or credibly speculated.
    Seems obvious. A positive number minus a smaller positive number equals a number greater than zero, and a volume greater than zero is not a singularity.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  40. #1465
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Seems obvious. A positive number minus a smaller positive number equals a number greater than zero, and a volume greater than zero is not a singularity.
    The radius of the universe was smaller than the Swarzchild radius for that mass.

    Why was it expanding, and not collapsing under the curvature of spacetime caused by that much mass-energy in that small a volume?
  41. #1466
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    I think the matter vs antimatter thing is really a simple question of probability. If we flip a coin 100 trillion trillion times, are we to expect there to be exactly 50 trillion trillion heads? The probability of that happening is actually very slim indeed. It's extremely likely that one side will very slightly dominate over 100 trillion trillion flips. The same happened with antimatter vs matter. There was perhaps 0.1% more matter, so it won. It actually seems fairly simple to me. The scary thing about this hypothesis though is that basically god was rolling dice when he made the universe, and a double six would've meant exactly 50-50 ratio, total annihilation, and no universe*.

    * as we know it
    Whether or not and how often an interaction or reaction takes place is probabilistic in nature.
    Conservation laws are not probability based.

    With virtual particles, the conservation laws are bent by unobservable events, but all observable events follow conservation laws.
  42. #1467
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    But the energy still exists. It must do. What happened to that energy? The energy content of the universe is exactly the same today as it was 10^-43 seconds after big bang. And since energy is mass... well that "stuff" just changed, it didn't disappear.
    Yes. The mass-energy is conserved.

    It has been transformed predominantly into heat and the gravitational potential energy stored in the curvature of spacetime.

    The point is that matter and anti-matter annihilate each other in pairs by all known observed interactions. There are only hypothetical and unobserved interactions in which matter and anti-matter annihilate at a rate other than 1:1.
  43. #1468
    Quote Originally Posted by MadMojoMonkey View Post
    Why was it expanding, and not collapsing under the curvature of spacetime caused by that much mass-energy in that small a volume?
    Umm... because it was rotating at an incomprehensible rate, and therefore inertial forces were of the order required to do battle with gravity? That's my best guess.

    It has been transformed predominantly into heat and the gravitational potential energy stored in the curvature of spacetime.
    Right, so the energy still exists. The "annhiliation" of the matter and antimatter isn't annihilation in the context of "obliteration", it's to "convert to radiation". So all that matter and antimatter that was annihilating each other in the very early universe, it still contributes to the mass of the universe, because its energy remains part of the system. It's still "stuff".
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  44. #1469
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Umm... because it was rotating at an incomprehensible rate, and therefore inertial forces were of the order required to do battle with gravity? That's my best guess.
    My only critique is that IF the universe started as an idealized point mass (not even sure how absurd that is), then the notion that it was rotating is absurd. A thing with no measurable length dimension cannot be said to be rotating in any meaningful way.


    ***
    Just to be clear, this is a separate topic, which we are discussing at the same time.

    Quote Originally Posted by OngBonga View Post
    Right, so the energy still exists. The "annhiliation" of the matter and antimatter isn't annihilation in the context of "obliteration", it's to "convert to radiation". So all that matter and antimatter that was annihilating each other in the very early universe, it still contributes to the mass of the universe, because its energy remains part of the system. It's still "stuff".
    Which is true, but doesn't address, "Why, of all the stuff that's left, is there ANY matter, and not just energy?"

    "So all that matter and antimatter that was annihilating each other in the very early universe"

    Ahem: most of that matter and all of that antimatter
  45. #1470
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Time doesn't flow backwards, as far as we can observe. It flows at different rates for different observers, but always in the same direction. That reminds me of the second law of thermodynamics. Is time just the flow of entropy? Nature's eternal quest for equlibrium?
    The "thermodynamic arrow of time" is directly related to the 2nd Law of Thermo.
  46. #1471
    Quote Originally Posted by mojo
    My only critique is that IF the universe started as an idealized point mass (not even sure how absurd that is), then the notion that it was rotating is absurd. A thing with no measurable length dimension cannot be said to be rotating in any meaningful way.
    I suppose it could be rotating at infinity rps. Meaningful? Well no, not to us, but I'm thinking of an ice skater spinning and stretching her arms out... as the universe expands, the rotation slows... during the EW epoch, the universe was tiny, but not a singularity... rotation can be meaningful in this world, and therefore so too can intertial forces. Before then, who knows? I expect the universe to be rotating faster and faster as we go closer and closer to the big bang. That is, of course, assuming that the torus model, which I particularly like, is incorrect. In this model, the big bang is merely the centre of the universe, which is already rotating. Expansion is merely motion through the geometry of the universe, driven by outward pressure from the central singularity, and accelerated by inertial forces, which we call dark energy. I like this model more than the problematic ever-expanding model.

    Which is true, but doesn't address, "Why, of all the stuff that's left, is there ANY matter, and not just energy?"
    Did you not like the answer "probability"? I have another potential solution... initial conditions of matter vs antimatter were an odd number. If one particle of matter survives, along with all the energy that's left over, then we still have an interaction. There is a universe. Perhaps the universe as we know it "grew" from one solitary matter particle.

    idk, but in a truly random world, it seems statistically unlikely that with such large numbers of particles, there would be an exact match. So perhaps the probability answer is the easiest to digest.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  47. #1472
    Quote Originally Posted by MadMojoMonkey View Post
    The "thermodynamic arrow of time" is directly related to the 2nd Law of Thermo.
    Something I was watching about entropy yesterday seemed to suggest that it's the result of probability. This confused me, because they kept saying heat NEVER spontaneously moves from cold region to warm. Surely if probability governs this, then we should expet to see it happen rarely?
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  48. #1473
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    I suppose it could be rotating at infinity rps. Meaningful? Well no, not to us, but I'm thinking of an ice skater spinning and stretching her arms out... as the universe expands, the rotation slows... during the EW epoch, the universe was tiny, but not a singularity... rotation can be meaningful in this world, and therefore so too can intertial forces. Before then, who knows? I expect the universe to be rotating faster and faster as we go closer and closer to the big bang.
    OK, what is rotation? Motion about an axis, yeah?
    How can an object with no part of it lying off of any axis be said to be moving about said axis?
    (Granted this is all predicated on my IF an idealized point mass... statement)

    We're not talking EW epoch. We're talking quark-gluon plasma. EW epoch is post-inflation.

    If the universe is rotating, then we should see effects of centrifugal forces in our non-inertial, rotating reference frame on some length scales in the universe. There would be a definite center of rotation, i.e. center of the universe.
  49. #1474
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Did you not like the answer "probability"?
    As I explained, probability describes the rate of a process happening, not the outcome.

    To determine the rate of a nuclear reaction or interaction, you first calculate the probability of the outcome happening per chance to happen, then multiply by the chances to happen.
    Each observable outcome is a deterministic state, and the sum of probabilities of all observable outcomes is always 1.

    Probability describes whether or not a thing happened, it doesn't alter the outcomes of the thing happening.

    Quote Originally Posted by OngBonga View Post
    I have another potential solution... initial conditions of matter vs antimatter were an odd number. If one particle of matter survives, along with all the energy that's left over, then we still have an interaction. There is a universe. Perhaps the universe as we know it "grew" from one solitary matter particle.
    That explains the existence of 1 piece of matter in the universe, not the 10^big other particles out there with no anti-particle partner to annihilate with.
  50. #1475
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Something I was watching about entropy yesterday seemed to suggest that it's the result of probability. This confused me, because they kept saying heat NEVER spontaneously moves from cold region to warm. Surely if probability governs this, then we should expet to see it happen rarely?
    Thermodynamics describes systems with large numbers (greater than Avogadro's number) of particles.
    The statements of thermodynamics came about to explain and understand experimental results prior to the quantum description of nature.
    The statistical statement that heat never flows spontaneously from cold to hot is experimentally verified for systems of particles.
    Statistically speaking, the "never" is an overstatement, but not a terrible one. The equipartition theorem states, broadly, that systems of particles tend toward thermal equilibrium, and not toward isolated regions of high and low temperatures. "Tend toward" is a statistical statement, and we generally look at the large ensemble of particles as a dynamic equilibrium.

    A moving pendulum is in dynamic equilibrium. At any given time, it's total energy is constant, but whether that energy is kinetic or potential varies.
    This is similar for temperature. At any given time, the individual atoms of a molecule can have dramatically different thermal energy, but the overall energy of the molecule remains relatively constant and in thermal equilibrium with its environment.


    However, Quantum Mechanically, there is no such thing as entropy. All QM processes are time-reversible. I.e. any process that is observed to happen forward in time is also observed to happen in another experiment, but in the opposite order, and with particles and anti-particles swapped.

    So entropy is a breaking of symmetry at some scale of particle interactions?
  51. #1476
    Quote Originally Posted by mojo
    If the universe is rotating, then we should see effects of centrifugal forces in our non-inertial, rotating reference frame on some length scales in the universe. There would be a definite center of rotation, i.e. center of the universe.
    Well yeah. That centre is all around us in every direction... the past. We can't see where we're going, only calculate it. The further ahead we look, the further back in time we're seeing, and the bigger the light cone required to calculate where we're going. How long before that light cone becomes the observable universe? At that point we are utterly blind to our future.

    Dark energy is why we're told the universe's expansion is accelerating. That there is an outward motion from the centre, so why does dark energy not hint at a rotating universe with a definite centre of rotation? Because we see the acceleration in all directions? Of course we do! We're looking at the past, not the future!
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  52. #1477
    So entropy is a breaking of symmetry at some scale of particle interactions?
    It's really hard to get the concept of symmetry in the context of physics, but I think I'm getting there.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  53. #1478
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Well yeah. That centre is all around us in every direction... the past.
    If everywhere is the center, then it wasn't rotating at the initial moment of the big bang (because this affirms the point-mass assumption).

    Quote Originally Posted by OngBonga View Post
    We can't see where we're going, only calculate it.
    This is called the "psychological arrow of time."
    Rather the psychological arrow of time says we understand that time always flows in the same direction because we can remember the past, but not the future.

    Quote Originally Posted by OngBonga View Post
    The further ahead we look, the further back in time we're seeing
    The further away we look, the further back in time we're seeing.

    Quote Originally Posted by OngBonga View Post
    , and the bigger the light cone required to calculate where we're going.
    What?
    What does the knowledge of the distant in both space and time have to do with...?

    The vertex of a light cone is a spacetime event (in a 2-d plane, where one axis is distance and the other is time, so kind of a 1-D plane in time). The light cone describes that event's possible causal relationship with the rest of spacetime. The light cone is infinite in both directions, and contains all possible causal pasts in one direction and all possible causal futures in the other direction. Any spacetime coordinate not contained by the cone cannot have caused the event at the vertex or be affected by the event at the vertex, due to it being too far away in space and too close in time for the information from the event at the vertex to travel there at the speed of light.

    Quote Originally Posted by OngBonga View Post
    How long before that light cone becomes the observable universe? At that point we are utterly blind to our future.
    There will always be spacetime coordinates which are not causally related to other spacetime coordinates, based on the fact that the speed of light is finite.

    Look at any straight line through the universe at a single moment in your spacetime frame. Pick any point on that line. It is not causally related to any other point on the line in that frozen instant, because it takes some time for a signal moving at finite speed to move away from it.

    There is a unique light cone at every point in the universe which corresponds to that point in both space and time, which is the light cone's vertex.

    If you're talking about the big bang's light cone, then it already encompasses everything we know, because we know we are causally linked to the big bang, so must be within its light cone, like the rest of the universe.

    Quote Originally Posted by OngBonga View Post
    Dark energy is why we're told the universe's expansion is accelerating.
    But it's a non-answer.

    Why is the universe accelerating?
    Dark energy.
    What's dark energy?
    It's what we're saying is making the universe accelerate in its expansion.
    What is it beyond that, though?
    Dunno.
    Why are you even talking about it, then?
    It's kind of a place-holder name while we look into it more.
    ... and it sounds cool.

    Quote Originally Posted by OngBonga View Post
    That there is an outward motion from the centre, so why does dark energy not hint at a rotating universe with a definite centre of rotation? Because we see the acceleration in all directions? Of course we do! We're looking at the past, not the future!
    SAME acceleration in all directions. Only a function of distance, not direction.

    I don't understand your past/future argument, here.
  54. #1479
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    It's really hard to get the concept of symmetry in the context of physics, but I think I'm getting there.
    Jury's out. I'm still not confident and posing a question, there.
  55. #1480
    I don't understand your past/future argument, here.
    We see expansion in every direction. But we're looking at the past, so what we're observing is past expansion, not present expansion.

    SAME acceleration in all directions. Only a function of distance, not direction.
    In a 3D model, sure. But this is 4-dimensional expansion. We're talking about spacetime, not space. The same acceleration in all directions is because we're always looking in the same direction... the past.

    If we're seeing expansion at the very edge of the observable universe, then we're witnessing the expansion of the early universe, not the now universe. We know that was insane expansion. I mean, if we're seeing an acceleration of expansion, then surely what's actually happening is expansion is slowing down, because we're witnessing faster acceleration in the distant past to what we observe locally.

    I'm just confusing myself here. I'm sure that made sense before I read it back.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  56. #1481
    Quote Originally Posted by mojo
    Block holes don't trap light by slowing it down. They trap light by red-shifting it to the limit of infinite red shift, which has infinite wavelength, and therefore 0 energy.
    So the Newtonian view of the event horizon representing the region where escape velocity is c is... a coincidence? Or is it the same kind of coincidence that inertial and gravitational mass are... ie different ways of measuring the same effect?
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  57. #1482
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    We see expansion in every direction. But we're looking at the past, so what we're observing is past expansion, not present expansion.
    This is one reason why we know how much the universe was expanding in the past compared to now.
    This is one piece of evidence that the expansion is accelerating.

    We're looking into the past, but the closest things to see (which are, admittedly, pretty far out there) are still relatively not that far in the past compared to the CMBR. So we have a long record of what the expansion was over a wide span of time.

    Additionally, we've been watching the sky with decent instruments for a while now. We compare the past images to the present images with spectroscopy and we can see the red shift has changed.

    Quote Originally Posted by OngBonga View Post
    In a 3D model, sure. But this is 4-dimensional expansion. We're talking about spacetime, not space. The same acceleration in all directions is because we're always looking in the same direction... the past.

    If we're seeing expansion at the very edge of the observable universe, then we're witnessing the expansion of the early universe, not the now universe. We know that was insane expansion. I mean, if we're seeing an acceleration of expansion, then surely what's actually happening is expansion is slowing down, because we're witnessing faster acceleration in the distant past to what we observe locally.

    I'm just confusing myself here. I'm sure that made sense before I read it back.
    We're looking into the past, but it's still moving in chronological order.
    The scientists working on this know the GR much better than you and I. I'm certain the many measurements of the Hubble constant and the cosmological constant haven't all accidentally made some mistakes that end up all getting the sign (+/-) of their estimate wrong.
  58. #1483
    I'm still confused.

    If the universe's expansion is accelerating, then why aren't nearby galaxies (more recent) drifting apart at a faster rate than distant ones (less recent)? Why is it the other way round? Why was expansion greater in the distant past than it was in the recent past?

    What does the CMB tell us about the rate of expansion? Are we seeing an accelerated increase in wavelength? That would be pretty hard to explain without conceding the argument.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  59. #1484
    Additionally, we've been watching the sky with decent instruments for a while now. We compare the past images to the present images with spectroscopy and we can see the red shift has changed.
    I'm not arguing the universe isn't expanding. I still anticipate red shift.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  60. #1485
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    I'm still confused.
    I have to take some responsibility. I'm confused by some of this, too.
    My responses in this conversation are bound to have some of my misunderstandings woven in there as I work my way through some of this.
    I've tried to use question marks where appropriate.

    Quote Originally Posted by OngBonga View Post
    If the universe's expansion is accelerating, then why aren't nearby galaxies (more recent) drifting apart at a faster rate than distant ones (less recent)? Why is it the other way round? Why was expansion greater in the distant past than it was in the recent past?
    The spacetime in between galactic clusters is expanding. Stuff with more spacetime in between us and it will be moving away from us more quickly 'cause there's more stuff expanding in between us.

    Quote Originally Posted by OngBonga View Post
    What does the CMB tell us about the rate of expansion? Are we seeing an accelerated increase in wavelength? That would be pretty hard to explain without conceding the argument.
    Well, the photons' wavelentghts in the CMB have red shifted significantly, and measuring that red shift tells us the age of the CMB.

    IDK if we've measured a change in the red shift of the CMB.
  61. #1486
    I really enjoy reading this thread. I don't think MMM gets enough credit for not being a snobby ass when it comes to talking about this stuff with people. I know I tend to do that as do most people.
  62. #1487
    Quote Originally Posted by Savy View Post
    I really enjoy reading this thread. I don't think MMM gets enough credit for not being a snobby ass when it comes to talking about this stuff with people. I know I tend to do that as do most people.
    I really love talking shit in this thread. Obviously I like to talk about this kind of stuff with my friends, but I'm not IRL friends with a physicist, so it's really something I appreciate to be able to bounce my stoned ideas off someone qualified to refute them.
    Last edited by OngBonga; 03-23-2017 at 10:39 AM.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  63. #1488
    Quote Originally Posted by mojo
    I have to take some responsibility. I'm confused by some of this, too.
    Yeah I think my confusion is based on my misunderstanding of what "expansion" actually is.

    There is a feeling in me though that we're missing something simple, perhaps something as simple as an optical illusion. The fact we naturally think in three spacial dimensions is a hinderance to our intuition, imo. We're travelling through spacetime away from every direction we look in, and that isn't easy to imagine. Our motion is towards what we can't see, spactime that is yet to exist.

    Perhaps that's where the expansion is. We're moving into expanded space, it expands as we move into it.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  64. #1489
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by Savy View Post
    I really enjoy reading this thread. I don't think MMM gets enough credit for not being a snobby ass when it comes to talking about this stuff with people. I know I tend to do that as do most people.
    Thanks.

    I strongly believe that if I can't explain something to someone who is trying to understand it, then I don't understand it.

    It's not always true. There can be plenty of reasons to complicate this, but it serves me well most of the time.
  65. #1490
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    There is a feeling in me though that we're missing something simple, perhaps something as simple as an optical illusion. The fact we naturally think in three spacial dimensions is a hinderance to our intuition, imo. We're travelling through spacetime away from every direction we look in, and that isn't easy to imagine. Our motion is towards what we can't see, spactime that is yet to exist.

    Perhaps that's where the expansion is. We're moving into expanded space, it expands as we move into it.
    It bums me out a bit that someone with your interest and intelligence isn't more directly involved in the field.

    I mean... if you spent a week or two studying a book on GR, you'd know more about it than I do, probably. Your background understanding of Newtonian concepts is competent for any undergrad. I'm sure the calculus and linear algebra will be painful to learn, but you'd be good at it. You may not love doing it, but you'd love knowing that you understand the inner workings of GR.

    Plus, you're already familiar with light cones and other stuff that an undergrad has no knowledge of coming into the program.

    ***
    I mean... its selfish of me to want you in my field, but damn if you don't have excellent scientific instincts.
    Some scientific field would greatly benefit by you being in a building where they do stuff.
  66. #1491
    Quote Originally Posted by mojo
    It bums me out a bit that someone with your interest and intelligence isn't more directly involved in the field.
    Not sure if this post is a compliment or a moan! I think a bit of both!

    Honestly, it bums me out that I was so smart at school but left with no qualifications. I'm not getting into why that was, other than to say it wasn't my fault.

    Obviously I take responsibility for my actions (or rather, lack of) since becoming an adult, and certainly I could have studied better at college instead of drinking and smoking, but I was fresh out of an oppressive naughty-boys school regime and released into pure freedom, so it's no surprise I just did what I wanted to do... it was the first time in my life I had such freedom.

    I dunno, I guess there's a part of me that wants to learn, and a part of me that just wants to carry on being free.

    If I were going to study, I think it would have to be physics. I have an interest too in environmental sciences, but since I have controversial views about global warming, I think it's probably best I avoid that field! Physics isn't politically controversial, at least not to the same degree.

    Will I ever study? Possibly. I mean I'm seriously looking to get the fuck out of my shitty town and into the countryside. Once I've done that, I'd like to think I'll have more motivation. Until then, I'll probably just carry on as I am... getting stoned and learning what I can be bothered to learn, while talking shit about what I'm learning and how I interpret it. That must be better than doing nothing! At least I'm well placed if I eventually decide to study formally.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  67. #1492
    To give an example what I'd be like studying environmental science, when I studied psychology at college, it took me about a month before I started rejecting Freud and his ideas, arguing that he was applying his fucked up thoughts as a kid to everyone instead of acknowledging he was a wrong-un. I wanted to study Jung, and felt that were were learning the history of psychology, rather than psychology itself. Can you imagine what I'd be like when I'm being taught about climate change?
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  68. #1493
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Not sure if this post is a compliment or a moan! I think a bit of both!
    How could it possibly not be both?

    Quote Originally Posted by OngBonga View Post
    I dunno, I guess there's a part of me that wants to learn, and a part of me that just wants to carry on being free.
    pffft.
    Ignorance is a cage, man.
    *cough cough*


    ***
    Your controversial views about global warming are no reason to stay away if you're interested.

    In the sciences, we welcome controversial views. If data can't refute your views, then they're are no less valid than more popular unrefuted views.

    Einstein's relativity was controversial.
    QM was controversial.
    Simply defining "observe" is still a bit controversial in physics.
    Last edited by MadMojoMonkey; 03-24-2017 at 12:24 PM.
  69. #1494
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Quote Originally Posted by OngBonga View Post
    Can you imagine what I'd be like when I'm being taught about climate change?
    I imagine you'd be, like, relieved that you're in a hard science rather than a soft science.
    Your challenging questions will be answered with data or a nod that it's a good question. Not with hand-waving and conjecture.

    I imagine you'd be, like, "What a relief that what counts as knowledge in this field isn't just whatever BS sounds good to my culture right now."


    (Sorry, psychologists. My views on psychology can fall toward pretty rude at times. I don't think all psychology is misguided, but a lot of it is more a reflection of culture than of any hard, permanent truths about the mind.)
    Last edited by MadMojoMonkey; 03-24-2017 at 12:27 PM.
  70. #1495
    Quote Originally Posted by mojo
    In the sciences, we welcome controversial views.
    To a degree. The problem with disputing climate change is that you get treated the same as flat earthers, creationists, 9/11 truthers, holocaust deniers. You'd quickly be cast to the fringes.

    I imagine you'd be, like, relieved that you're in a hard science rather than a soft science.
    Climate change is way too politicised for me to consider it a hard science. There's too much external influence.
    Quote Originally Posted by wufwugy View Post
    ongies gonna ong
  71. #1496
    Jack Sawyer's Avatar
    Join Date
    Jan 2007
    Posts
    7,660
    Location
    Jack-high straight flush motherfucker
    Quote Originally Posted by OngBonga View Post
    To a degree. The problem with disputing climate change is that you get treated the same as flat earthers, creationists, 9/11 truthers, holocaust deniers. You'd quickly be cast to the fringes.



    Climate change is way too politicised for me to consider it a hard science. There's too much external influence.
    You bring forward your hypotheses and other scientists proceed to tear them to shreds. If they are bulletproof, they will withstand the intense scrutiny by other scientists, and if not, they will falter.

    The scientific method is an ongoing process. This is why science has little bullshit. It's not based on faith nor feelings, rather objective testing and retesting and scrutiny. You cannot be cast to the fringes if your data holds. If it doesn't and still you claim such findings, then yes, you will be declared a loon.
    My dream... is to fly... over the rainbow... so high...


    Cogito ergo sum

    VHS is like a book? and a book is like a stack of kindles.
    Hey, I'm in a movie!
    https://www.youtube.com/watch?v=fYdwe3ArFWA
  72. #1497
    Quote Originally Posted by Jack Sawyer View Post
    This is why science has little bullshit. It's not based on faith nor feelings, rather objective testing and retesting and scrutiny. You cannot be cast to the fringes if your data holds.
    Being a little idealistic there pal. Obviously the "right" side tends to pull through but this process can certainly take longer than a persons remaining life.
  73. #1498
    CoccoBill's Avatar
    Join Date
    May 2007
    Posts
    2,175
    Location
    Finding my game
    I was going to ask about this but now feel I don't have to.

    https://drivetribe.com/p/R5Q6z6jqSgG...Q8uVDBOg8SjjpA

    If, though, you feel you can add something to it, pls do.
    Our brains have just one scale, and we resize our experiences to fit.

  74. #1499
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    Torque is hard to understand. If anyone tells you otherwise, they're a liar and they want something from you.
    Even physicists who totally get it now had a hard time learning it. It's tricky. It does unexpected things sometimes.

    Fundamentally, a torque is the rotational equivalent of a force. A force causes an acceleration in a straight line, and a torque causes a spinning acceleration.

    In physics, we describe a lot of things with vectors. Vectors have a magnitude and a direction. An arrow has a length and a direction. We readily use arrows as symbols for vectors, with the magnitude of the vector corresponding to the length of the arrow, and direction is same for both.

    With force, if your butt pushes on the chair with your weight, we can describe that force with a vector located at your butt and pointing down. It's length would correspond to your weight. It's pretty straight forward. Your butt pushes down, so the arrow points down.

    With torque it's trickier. A thing starts spinning. Part of it is moving in every direction (except the directions parallel to the axis of rotation). There's no unique direction which indicates what the torque is doing. The axis of rotation would be the ideal place to put the vector, but that exact point doesn't move at all.
    So we make an executive decision.
    We decide to point the torque vector along the axis of rotation. This isn't fully solving the problem, though. The axis goes both ways. I mean... there's a spinning thing, and the axis goes through it. So depending on which side we attach the torque arrow, it could be flipped 180 in direction.
    Another executive decision.
    We still need to link the direction of spinning to the arrow, too. It could be going clockwise or counterclockwise (from a defined coordinate perspective). We can link the direction of rotation with the 180 flip of the arrow and clean up both problems if we simply pick a standardized way to link the direction of the spinning to the direction of the arrow which describes the vector which describes the spinning.

    We use the right hand rule.
    I can get into this in more detail if you like. For now, it's enough to say
    if I open my right palm with my thumb out,
    then close my fingers, keeping my thumb out,
    my thumb points in the direction of the vector which describes the spinning of my fingers.

    (Notice that if you do this with your left hand, it's a mirror image, and flips the direction of the thumb relative to the rotation. We could have used this rule in our 2nd executive decision. Which we use isn't relevant, so long as all of our math and physics is consistent. The right hand rule comes up a lot, so just go with it... even if you're left-handed.)

    Here's a somewhat more involved explanation of torque as pertains to not cars.
  75. #1500
    MadMojoMonkey's Avatar
    Join Date
    Apr 2012
    Posts
    9,424
    Location
    St Louis, MO
    This is worth the extra ~4 minutes if the other video didn't bore you.


    "None of this is intuitive. None of this is intuitive."

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •