« on: 14/11/2019 13:18:46 »
Of course. Sperm do not all contain identical genetic material.
Maybe your son would have been a girl.
Maybe your son would have been a girl.
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The sequence 1, 1½, 2, 2½, 3...... obviously (a) is infinite and (b) has twice as many members as the sequence of integersIf there is a value for 'how many members', then it isn't infinite. If there isn't, you can't meaningfully speak of doubling it. There exists a bijunction between the integers and the latter sequence you give, thus there are no more meinmbers one sequence than the other.
If we are at a point, does that not imply that there is a before and after relative to that point?There is (potentially) a before and after to any point in a temporal space. On the other hand, I by no means consider myself to be at only one such point. I'm at quite a number of them, none particularly special.
Didn't say I would not accept a different definition. I just personally would not choose the word to mean that other thing.Quote from: HalcI personally don't use the word 'eternity' to mean anything except a length of time.If your interpretation of eternity is that it is a length of time, and mine is that it is not, we will, probably, never make a great deal of progress, though.
In the “infinite universe” in which there is no change and no time;That I do not agree with. Infinite or not, there is very much change. At time 1 the candle is taller than at time 2, and then there's the rabbits. The count of rabbits is different at one time than at a subsequent one, and that means there is change.
Jibes then. Typo, sorry.Quote from: HalcSorry, but I cannot think how any of this jives with science. The BB theory is an explanation of the evolution of the universe since the BB, but not a model of how it came to be in the first place.If that is your understanding of the quote from me; all I can say is that we speak different languages. Your introduction of “dancing”, if intentional, is a colourful usage.
As a precursor to and cause of the big bang, yes. I don't pretend to understand it all. Look at some of Sean Carroll's publications. He's on top of that sort of stuff. I'm only mildly interested since I don't really care what caused the big bang. That event didn't do anything silly like 'cause existence', except it sort of did since it caused the only sort of existence that makes sense to me.Quotethese are typically QM theoriesYou seem to be saying that QM theories are applicable to the “something” posited as a precursor to the Universe. Could that be right?
I personally don't use the word 'eternity' to mean anything except a length of time. But I do use the word 'eternal' to mean 'not contained by time'.Quote from: BillA major problem seems to be that, however much the people providing the explanation insist that eternity is not a length of time, they inevitably lapse into treating it as though it were.Your response seem to reinforce this. Was that intentional?
So in neither of the “exceptions” you give is actually an exception, but then, I think you acknowledge that; so was there a point that I've missed?Nope. Just a habit to look for exceptions whenever somebody makes a statement with 'always' or 'never' in it somewhere.
Was the BB the beginning of the Universe? Of course, scientific veracity is not a matter of democratic “vote”, but informed opinion seems, widely, to hold that this is our best current theory. Given that response; the next question must be: “Did anything exist before the BB?”. A few decades ago, the answer usually found was, “nothing”. However, two things have happened to that “nothing” over time.Sorry, but I cannot think how any of this jives with science. The BB theory is an explanation of the evolution of the universe since the BB, but not a model of how it came to be in the first place. So it is the beginning of time as we know it (that which is measured by seconds or by vibrations of certain atoms, neither of which exists outside the BB), but the theory does not posit the absence of anything 'on the other side', which is arguably not 'before' and certainly doesn't posit 'nothing'. I'm no expert in the theories that do concern such things, and have little opinion on them, so I'll just say that theories exist, and I'm not aware of any of them suggesting a 'nothing', although 'no thing' is appropriate since the typical 'thing' we know like an atom likely doesn't exist there. All the theories seem to fall under 2) below, and not 1) here.
2. It has been replaced by the idea that there would almost certainly have been something, but we don’t know what it was. This must be the “safer” option, but still leaves the question as to the whether we can say something about this “something”, that is not simply conjecture or philosophy.Conjecture yes. Philosophy no, since these are typically QM theories and lead to models that make predictions.
There are those who hold that something could “emerge” from nothing, but I have yet to find an explanation that didn’t involve treating “nothing” as “something”.I agree with this.
A “get-out clause” is that science works with models, and we cannot model “nothing”. How satisfying is this?I've never seen a scientific model positing something from nothing. It seems contradictory. Science concerns the mechanism involved, and no viable mechanism does a 'something from nothing'. It is thus a philosophical stance, and a weak one since it defies logic for the reasons you give.
Answers to Q2 often devolve into discussions that, at best, are peripheral to the essential issue. A major problem seems to be that, however much the people providing the explanation insist that eternity is not a length of time, they inevitably lapse into treating it as though it were. Infinite regression is often a major component of these lines of reasoning, and the presence of the word “infinite” leads to an apparent assumption that the “sequence” under discussion is actually infinite, i.e. it somehow extends to infinity. This may be acceptable in principle, but has no practical counterpart.Language issues aside, our universe seems infinite in some ways: There is no apparent boundary to spacetime except the big bang itself, and possibly the big rip on the other side. Doesn't mean it isn't bounded, but the boundary isn't apparent. So it could work either way. I don't think it matters. The existence (as opposed to its nonexistence) of either a finite nor an infinite structure can be explained. It being finite or not seems to play no role in this essential issue.
3. Something that is finite can never become infinite.Trying to find exceptions to this. How about this?:
Really not intuitive... "So in the current inertial frame of either twin, the other twin is aging slower".That is basic time dilation. Time 'runs' at full speed if you're stationary, and all objects are stationary in their own frames. This is consistent with Galilean relativity: "Physics is the same in any frame". Time dilation means that time slows down for moving things, and in any frame, it is everything not stationary in that frame that is moving. So relative to the twin in the ship, the Earth twin is the one moving. Earth is just another ship after all, just a larger one than usual.
What I just can't get past is this idea that time appears to be slowing down for both twins, it just depends on whether you are measuring from one twin's position or the other's...Be careful about 'appears to be'. Time is computed to be slower in these other frames. The twins are not in each other's presence, and hence neither has a direct way to measure the other. In fact, if a clock is approaching you fast, it will 'appear' to be running faster, but that's mostly due to Doppler effect, and is why light from approaching galaxies is blue shifted despite being dilated a bit slower.
Perhaps, if it's not too much of a bother, and you understand my confusion, do you happen to know of any links to explanations that might help me...just idle curiosity as I don't NEED to know this.https://en.wikipedia.org/wiki/Relativity_of_simultaneity
The trouble I've had is that everything I've read/watched on Youtube that describes, for e.g., the twin thought experiment, always takes as a given that the "reference point" is the twin/you "here on earth"OK, I know that. For that very reason, I always choose the frame of the guy in the ship or the guy in the train, which really helps one discard a lot of the assumptions about absolute motion. With a westbound train it is pretty much true. A really fast train going west is actually more stationary (accelerates less) and has Earth rotating underneath it. Few trains move at fast enough speeds to actually cancel rotation, but jets sometimes do.
But if I assume that "I" am the other twin, the one zooming off in the space ship how can I demonstrate/reason that it is "I" that am moving and not the twin on earth that is zooming away from me at an equal and opposite velocity??Colin's answer to this is correct. There is no way to detect absolute motion, or more precisely, no local test. The two twins moving apart at high speed is entirely symmetrical, and thus each ages slower in the frame of the other. But one of them significantly changes reference frames, and does so a long distance from the other. That's what makes the difference when they are reunited. Remember RoS?
And as for astronomers not being able to observe this mass loss effect.They should. The sudden disappearance of a large star's worth of mass would generate a huge single spike in gravity waves that would dwarf the ripples detected by the close orbit. It would be comparable to somebody pulling down a trampoline and suddenly letting go, vs the small waves you get from twirling two bowling balls around each other on the trampoline. LIGO would have no trouble detecting it. It doesn't.
In this model there are no black holes. only super dense Netron stars that light can not escape from.If light cannot escape them, they're functionally the same as a black hole, despite what name you decide to give it.
Only thing this theory mentions is the flaw in the black hoke theory is that it cant explain what is between the event horizon and the singularity, or what a singularity is.A singularity is anywhere where the mathematics of standard physics breaks down, such as distance, force, time, whatever going to zero or infinity. There is a singularity at the event horizon, and there is another mathematical singularity at the center of a black hole, but only if it's a real black hole and not one of these compressed shell objects.
The original object wont retain the same gravitational field when it vanishes.Since this has never been observed, it's a pretty thin proposal.
The more massive objects, like the black hole at the center of our galaxy, according to this theory is just millions of these critical neutron stars near each other orbiting a common center. They haven't collided.A typical black hole is smaller than any neutron star, so one, let alone multiple neutron stars would not fit in there.
I am talking in regards to evidence of the dynamic steady state cosmology.That sounds pretty wrong. If the mass vanishes to elsewhere, why does the original object retain the gravitation field associated with the original mass. Neutron stars are nowhere near this limit since there are definitely small and more massive objects.
according to that theory, there is a limit to how much mass that can be in one given space, and the rest vanishes and comes out somewhere else.
So if you can find another orbiting star when these two neutron stars merge then, the orbit of that star will change due to the vanishing mass. Thus proving the validation of the theory.If they witness that, then I suppose it would validate the theory, but as I said, they've seen far more massive objects, so there seems to be no upper limit.
Given a full deterministic interpretation of QM (like what Bohm suggests) and a complete description of the wave function of the [system] (which includes the state of moon and anything else within 10 light seconds) plus all the immeasurable hidden variables involved, only then can an accurate prediction of [its state a few seconds from now] be made.This statement is wrong. One would need to include the full wave function and hidden variables of the universe to make a perfect determination of state 10 seconds from now since any interpretation of the nature I describe above (where the universe has a state) has causes that can come from outside the past light cone of the system being predicted, and from the future as well.
Do not blame science.You've been responding to a user that is no longer registered. Let me know how that works for you.
2. WIth LIGO up and running, we should be able in the future detect 2 neutron stars merging.Already did that. http://www.astronomy.com/news/2019/04/ligo-detects-gravitational-waves-from-another-neutron-star-merger
And if they merge and not orbit,They orbit until they merge.
then one of those masses should vanish.Mass cannot be destroyed. They become one object with mass nearly the same as the combined mass of the two. Some of the mass is sprayed into space as a result of the collision.
In fact, over 80% of it has been used up already. It will run completely out in 7.5 billion years, more due to the breakdown of the mechanism than to the tank running dry. In one billion years, the energy will become very difficult to access. The energy source for tidal energy is kinetic energy, not gravity at all. Gravity is a field or a force, not energy.Quote from: Dave LevSo, Tidal is based on Gravitational fields, it is renewable and it is not though of to be ceased in near future."Near future" being the operative word there. It will run out eventually.
The whole discussion is summed up here .https://m.xkcd.com/2217/Quote from: Dave LevDo you still see any contradiction with conservation of energy?You can answer that question yourself. Just ask yourself "does this create new energy?" If the answer is "yes", then you've contradicted the law of conservation of energy.
Because the wave function of a large object is negligible outside its classical radius (indeed you can use that as a definition of "mesoscopic") we can predict where a billiard ball will go.If this were true, they could publish tonight's billiards scores in today's paper. Only the one interpretation I mentioned actually asserts the game is fixed (completely determined) like that, and even then there is neither a way to 1) take anywhere near the necessary measurements, nor 2) perform the calculation, so no computer, even hypothetical, can actually perform such a calculation.
So if an astronaut left the space station and couldnt get back, or anyone's body was just let go in space would it freeze and stay like that for ever? Would it move or stay in one place?Being in a suit means you're under pressure, so the body might suffer a similar fate as one on Earth at a similar temperature, in an enclosed container. Space isn't particularly cold or hot as there is no matter to give it temperature, so the eventual temperature of the body in the suit will depend on how much time it spends in the sun or shade.
I guess what I've played isn't English Billiards. Thanks for the education.QuoteIn English Billiards ...My apologies, there are pockets.
Anyway, the fact remains that for a billiard ball p and x are so large compared with h that the indeterminacy of its position is negligible even when p is zeroTotally agree, but you're talking about measuring it, and not about predicting where it will be in the future. Yes, I can measure the position and momentum of a billiard ball to a lot of zeros of accuracy. No argument there.
I heard someone today saying, when talking about Voyageur 2, that it would go on travelling in space for billions of years. This suggests that it will never break down/'decay,change. is this true of anything that gets into space?All particles have a half-life of sorts, but given what space probes are made of, it is not of any real concern. Billions of years doesn't begin to touch that.
I thought I was quite careful. It's actually quite a weak statement since it references the limits of measuring something, and not magically having full knowledge of the state of a system.QM theory says no amount of measuring of a system will allow you to predict it.Be careful how you state this.
The wave function of a billiard ball is negligible in comparison with its apparent diameter, so for all practical purposes (e.g. potting the black) it is adequately predictable.I would disagree with that. You're thinking of a classic description of the ball, which isn't a wave function. A wave function might give probabilities of particles being measured here or there or not, and that function is unimaginably complex for something like a billard ball.
But its structure, mass and elasticity are all calculable from quantum mechanics.I agree that classic behavior and properties emerge from QM.
Indeed the "measuring" test isn't fundamental to QMI agree with this as well, but there are certain interpretations that give fundamental importance to measurements, and they don't all define measurement the same way.
Quoted from latest episode "eggs, eyes etc..., in answer to the question: "How fast a rocket can humans safely travel in?"Maybe where they are (Montreal?). At the equator, it is over 1000 mph. 25000 mile circumference in 24 hours, no?
"So the Earth rotates at 600 miles an hour.
So we're currently on the earth going 600 miles an hour, because we're on the earth we're also going 600 miles an hour.We're going 600 mph relative to the center of Earth. Speed is always relative, so not specifying the relation is wrong. I'm not moving 600 mph relative to my mailbox. I'm nearly stationary relative to that.
The Earth is speeding around the sun at 70,000 miles per hour. So we are also speeding around the sun at 70,000 miles an hour. The sun is speeding through the galaxy at 450,000 miles an hour, which means we're also spinning at 450,000 miles an hour."Just so, relative to the sun and the galaxy respectively.
I'm probably dim, but how can I understand "speed" in this statement? Are the references always implicit? For example, in the first statement "we're on earth going 600 mph", should I implicitly understand that the "reference" (if that's even the correct word!) is the centre of the earth, and this jumps to the sun in the second statement "The Earth is speeding around the sun at 70,000 miles per hour". In other words, in astronomy, when speeds are mentioned, should I just assume that I should understand the quoted speed relative to an "obvious" reference.You got it. Speed is always relative to something, and language usually lets you get away with letting it be implicit, but the reference is always there. The speedometer on my car shows speed relative to the road under it, and doesn't bother to say that explicitly.
The reason I'm asking the question is because I simply don't "get" relativity, time dilation etc...e.g. in the classic example of my "twin" charging off in a rocket at near the speed of light aging differently to me, am I not simply "aging" at the same rate relative to my twin, because relative to him/her, I'm charging off in the opposite direction at an equal and opposite speed, therefore cancelling out any warping of time?Under relativity, it is the other twin that is moving relative to either twin, so in the current inertial frame of either twin, the other twin is aging slower. Not intuitive, but that's how it works.
This is the second message of this type from different members. This wouldn't be an attempt to spam us, would it?It's about the 5th actually, different new member each time, same title.