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3. ## iNow

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## Popular Content

Showing content with the highest reputation since 03/28/04 in Posts

12 points
2. ## Mike Smith Cosmos

I was reading through Mordred's long standing thread on space and I came across some posts from Mike in the early part. Members may wish to know that Mike passed away earlier this month after a long standing degenerative illness (not covid). Mike was an interesting character, an artist with a degree in Physics and the founder of a successful manufacturing business before retirement to Cornwall. His artistic (dreamy) side gave him an unusual and sometimes frustrating perspective on Physics, especially later in life when we knew him. But he was a genuine character and sometimes offered suprising insights as well.
8 points
3. ## Rules update: bad faith discussions

Staff have decided to update the forum rules to include the following: This is in response to a number of threads and certain members who have made threads here under the premise of 'just asking a question,' only to reveal that they are in fact trying to peddle conspiratorial or otherwise nonsense ideas. While covered to some extent by pre-existing rules, we have decided to make it explicit that we will not be hosting these sorts of threads, if for no other reason than the fact that they are a waste of everyone's time.
8 points
4. ## Matter creates gravity

OK let's clarify something here. First consider the following definitions. Mass is resistance to inertia change Energy the ability to perform work. Spacetime a geometric model system with 3 spatial dimensions with 1 time dimension. In physics dimension is an independent variable or value that can change without affecting any other mathematical object. So how does mass curve spacetime. Well GR models bodies in free fall that is without any force applied. Time is given units of length and can be called an interval. This is done by setting c which is constant to all observers and adding a unit of time. So the time coordinate is given units of length by ct. $(t,x,y,z)=(ct,x,y,z)=(x^1,x^2x^3x,x^4)$ the last is in four momentum form for convenience as its useful to model a particle trajectory along the x axis. Now what is spacetime curvature. Well space is just volume... (Very important ) it isn't a stretchable bendable fabric... Those are just analogy descriptive. What spacetime truly means by curvature is the worldline paths for light it us the null geodesic. If you shoot two laser beams in flat spacetime those beams stay parallel. If spacetime is curved then the beams converge for positive curvature and spread apart for negative curvature. This is a consequence of how the mass term affects the time it takes for a particle to go from emitter to observer. That whole resistance to inertia. So let's drop two objects toward a planet. You have the usual Centre of mass. As the objects free fall they do not stay parallel. They will converge upon one another as they approach the center of mass. That what is really meant by curvature the free fall paths are curved. Not the volume of space.
8 points
5. ## When did God put the soul in humans during evolution?

So looking at the image below, it appears that Galagidae have recognizable soles, but Cynocephalidae do not : and when we look at a primate phylogeny, we see the split between these two groups is around 65 million years ago: So soles originated about 65 million years ago, give or take. You meant soles as in soles of the feet, right?
8 points
6. ## So are quantum entangled or teleported particles instantly there

So if I change the charge of one plate, somebody can measure an instantaneous change at the other plate. Wouldn't that be a violation of special relativity? @Menan You show that you do not understand entanglement. Let's go one step at a time. First a classical example. I have a bag of balls, they are all red or green. Without looking I pick two balls, and I put them in separate boxes. I keep one, and send the other far away. Then I open my box, and see it is a green ball. What can I conclude about the colour of the ball in the remote box? Right, nothing. And why? Because there was nothing special with my picks. It could have been two reds, two greens, or one red and green. Now I pick, looking of course, one red and one green, and put them in two separate boxes. So what I did here is 'entangle' the balls. Now I shuffle the two boxes, so that I do not know which one is which. If I open one, and see that it is red, I immediately know that the ball in the other box is green. And of course, this is independent on the distance. If I send the second box lightyears away, and only then open my box, I still know immediately what some alien sees when he opens his box. I know it because the observations are correlated. And the correlation already happened at the moment of my picks. That is the moment of entanglement. It is not when the boxes are opened. Now in quantum physics, there are processes where two particles pop out, which have e.g in one aspect always opposite values. Say the direction of spin. So if I measure the spin e.g. in a vertical direction, say it is 'up', then I immediately know that the other one will measure spin 'down', when also measured in the vertical direction. But as with the balls, the 'moment of entanglement' is when these particles popped into existence. But in quantum physics a few things are different: first, it is impossible to say which particle has which spin without measuring (it is as if I created the green and red balls, including their boxes, without knowing which ball is in which box). But as the two particles are entangled, if I measure both, the measurements will always be correlated. And there is nothing special with correlation: if I send one particle far away, and then measure my particle in the vertical direction, and the alien measures his particle in the same direction, I will always know what he measures: the opposite of my measurement. The 'spooky' aspect comes in when we do not know from each other in which direction we measure the spin. It can be vertical, horizontal, 30o, 45o, 55.3977o. What we find is that the correlation is stronger than one would expect if we would assume that the particles already had a definite spin from the beginning. But it still is correlation, not causation. As with the red and green balls, there is no direct causal relationship between my and the alien's observation. The causal relationship goes back to the moment of 'entanglement'. Everything afterwards is just correlation, and therefore cannot be used to transfer information. And because there is no causal relationship between my measurement of the spin of my particle, and the alien's measurement, I cannot use entanglement for sending information. And all this is very well understood by all quantum physicists, and is no secret at all.
8 points
7. ## Jordan Peterson's ideas on politis

You can label it Political Correctness, or whatever you wish. The fact is that our Western societies are now almost at a point where the individual right nt to be offended, trumps society's right to free speech. And where your own personal, subjective reality can be forced, under threat of law, on the rest of society. If it was someone in authority doing this to society, you would all label him a despot, or dictator, or fascist. When it is anyone with a gripe against the rest of society, or a pretentious, virtue signalling university student, who has no clue what being underpriviliged really is, you guys all stand and cheer, while disparaging those who stand up against the nonsense, claiming they are out of their area of expertise, or just in it for popularity and money. You guys need to give your collective heads a shake !
7 points

7 points
9. ## Can you be a scientist and still believe in religion?

Well, since Markus has expressed his desire to join a Monastery, I think that definitely answers the OP question. But, some words to Markus... ( no offence meant, just trying to lighten the mood ) A young monk arrives at the monastery. He is assigned to helping the other monks in copying the old laws of the church by hand. He notices, however, that all of the monks are copying from copies, not from the original manuscript. So, the new monk goes to the head monk to question this, pointing out that if someone made even a small error in the first copy, it would never be picked up! In fact, that error would be continued in all of the subsequent copies. The head monk, says, “You make a good point, my son.” He goes down into the dark caves underneath the monastery where the original manuscripts are held in a locked vault. Hours go by and nobody sees the head monk. The young monk gets worried and goes down to look for him. He sees him banging his head against the wall and wailing. “We missed the R! We missed the R! We missed the R!” “Father!” cries the young monk. “What’s wrong?” The head monk with tears in his eyes replies, “The word is CELEBRATE!"
7 points

7 points
11. ## My first thousand

Just did not want to let this pass without a party (Dutch treat...). You are all invited at the lakeside! (Just Click on the picture to see it full size.) Thank you to all from who I learned a lot, and also thank you all who understand less than I do about certain subjects, but force me me to rethink, or make my viewpoint clearer, or force me to read some book or article (again). I noticed that much of what I read is influenced by topics here in these fora. And thanks to those who make this forum possible, moderators, administrators, sponsors, etc. Up for the next 1000!
7 points
12. ## Special Relativity - simple questions?

SR does not claim that such an observer will always see the Earth clock run slow, if by see, you mean what his eyes or instruments directly record. In this usage of see, he will see it run at a rate of T = To ((1-v/c))(1+v/c))1/2 where v is positive if Earth and the Observer are receding from each other and negative if they are approaching each other. A factor contributing to this observation is the the distance and thus the propagation time for signals is constantly changing, getting longer when receding and getting shorter when approaching. This factor works out to be c/(c+v) When you factor this out of the first equation you are left with the time dilation equation. This means that there are two things to consider: what you see happening to the Earth clock, and what is happening to the Earth clock. So while while receding from the Earth, the observer will see the the 1000 Hz signal as being 500 hz and the Earth clock as ticking 1/2 as fast as his own,. Taking into account the effect of the increasing distance, he will determine that the Earth clock is ticking 0.8 as fast as his own. He will meet up with the object when his own clock reads 1.01.2022 (as the distance between Earth will be only 1.2 ly as measured by him and this is how long it takes to traverse this distance at 0.6c.) He will see the Earth clock reading 1.01.2021, but determine that it is 8.07.2021 on the Earth at that moment. Now at first, you might be tempted to think " But wait, if he sees 1.01.2021 on the Earth clock, and the Earth is, according to him, 1.2 ly away, wouldn't that mean that it should be 3.15.2022 on the Earth by his reckoning?" This is not the case. The light he is seeing at that moment left Earth at a time when the distance between them was less than 1.2 ly, so the time it took the light he is seeing took less than 1.2 years to reach him from the Earth. Now he accelerates in order to come start the trip back towards Earth. We will assume a minimal acceleration period. Now this is the part where people tend to get tripped up. After he is done and is now approaching the Earth and not receding, we will assume that he still reads 1.01.2021 on the Earth clock by visual means. However, he will no longer conclude from this that it is 8.07.2021 on the Earth. Instead he will conclude that it is 6.05.23. During the return trip he will see a frequency of 2000 hz from the signal and the Earth clock tick twice as fast as his own. But again, taking into account the decreasing distance effect, he will conclude that the Earth clock is ticking at a rate 0.8 as fast as his own. Thus he will see the Earth clock tick from 1.01.2021 to 1.01.2025, but conclude that it ticked from 6.05.23 to 1.01.2025 during his return leg. (see will see it tick off 4 years, but conclude that it ticked off 1.6 years. Again, it all come back to what happens during that acceleration period. As far as anyone at rest with respect to the Earth is concerned, nothing special beyond the standard SR effects take place. But for the observer actually undergoing the acceleration, things aren't this simple. For him, the rate at which clocks run depend on which direction they are from him relative to the acceleration he is undergoing and the distance from him in that direction. Clocks in the direction of the acceleration run fast, and those in the opposite direction run slow (beyond what he sees. This even effects clocks that share his acceleration. A clock in the nose of the Ship will run fast and one in the tail will run slow. ( in this case, since there is no changing distance between himself and the clocks, what he sees, will be in perfect agreement with what is happening to the clocks. While this may seem to be at odds with common sense, it is how a Relativistic universe works. A problem with your questions is that they only deal with particular points of the whole scenario without taking in the whole picture. It like comparing two men walking and only considering where they end up. Below we have the paths of two men, Red and Blue, over the same interval. If you just look at where they end up, you would conclude that Blue walked a shorter distance because he ends up closer to the starting point than Red does. But when you consider the whole interval, it is clear that Blue walked a further distance. The same thing is true with SR, if you only consider the end results, you are missing what is really going on.
7 points

7 points
14. ## War Games: Russia Takes Ukraine, China Takes Taiwan. US Response?

Despite a month of promises, on Thursday the 24th at night, conviniently while the Putin shitstorm started he reinstalled a prosecutor in the disciplinairy chamber who tormented a pregnant woman resulting in her death becuase of religious BS. The disiplinairy chamber is an illegal entity and a private tool of Kaczyński and Ziobro (minister of justice and prosecutor general in one person) and is the main reason which prevents us from receiving the 150 bln euro form the EU post Covid fund and results in us paying around 1mln euro in fines. Daily. The president is not autonomous, he's a tool and a clown, unfortunately. Just came back home from a day of trips, dropping people off at shelters and getting food and supplies.
6 points
15. ## What taxes a billionaire?

There are several parallel issues here. One is that wealth acquired by the ultra wealthy tends to get put into tax shelters and nebulous investments so it grows (but remains outside the system), whereas that same money in the hands of the less fortunate goes IMMEDIATELY into the community around them. They spend it on groceries and vehicle repairs and school clothes for kids and paying the electricity bill so it’s not dark in their apartment anymore at night and their kids can read. The providers of those goods and services in that community where this money is being spent ALSO spend the money once received for THEIR groceries and THEIR service needs and on THEIR kids. Dollar for dollar / unit for unit… the money in the hands of the less fortunate does more net good than money in the hands of the already fortunate. Yes, spending from the wealthy also creates jobs and injects money back into the system, but very little relative to money used in “trickle up” stimulation packages. Also, a bit of extra money in the hands of someone who already has a bunch of it doesn’t tend to change their behavior or encourage extra spending. Getting $1,000 tax break when you’re sitting on$50M isn’t going to suddenly result in them finally making a call to a plumber or the purchasing a new dishwasher… but for the person living paycheck to paycheck that money literally changes lives, gets spent and injected back into the system quickly, and results in lasting reductions in poverty and suffering. When you’re living at the margins, every dollar counts. It also costs a lot to be poor. When the washing machine breaks, you can’t afford a new one but you can afford to pump quarters into the machine at the laundromat… but that ends up being more expensive on net. When the car breaks down, you don’t get to work on time and you get fired. The rich, however, have tax protected ways of growing their wealth and can afford tax attorneys to hide it. Paying more tax has more impact on their ego than on their lived experience. The anger at the rich is out of hand, though. We need better policies and enforcement mechanisms, not more hate and vitriol directed at those doing better than us. Sadly, the anger is probably in large part intentionally being amplified by the very people on the receiving end. If they can keep everyone mad and focused on the wrong things, then the status quo remains stable and no progress or change gets made. Like most issues in economics, we make a huge mistake by treating it as a moral failure when at its core it’s a policy failure. Fixing the policy is just super hard because the people with the power to change the laws tend to be the same ones benefiting the most from them… and also because focusing on wonky policy details is hard for a public who’s often just trying to survive through to tomorrow and who’d much prefer throwing stones and being distracted with us/them tribalism. Perhaps this thread could try focusing on wonky policy details instead of distractions like yachts and steel boats… or not.
6 points

6 points
17. ## autism brain connectivity

I’m on the autism spectrum myself. The problem here is that we can’t isolate a specific sensory stimulus at the exclusion of everything else. So in this particular example, the stimuli coming from eye contact and his spoken words are both present, and both equally prominent simultaneously, which makes it difficult to focus on the actual content of either one of them. Averting eye contact simply makes it easier to focus on the person’s speech, so a lot of autistics will do this unconsciously and automatically. A better example would be a room full of people all talking to each other; it is very hard for me to just focus on what the person in front of me is saying, since I am forced to equally register all the other conversations in the room at the same time. There is no functioning filter there to limit and focus sensory stimuli - which is why we get sensory overload in certain stimuli-rich environments. Note that this is a matter of degree - different environments affect different autistic people in different ways and degrees.
6 points
18. ## 1. Thermodynamic work

A question about a sign convention that leads to a lot of confusion. This is not the only instance multiple sign conventions in Science. In this case it is a result of History. Thermodynamics was originally developed by physical scientists and engineers. They were concerned with making machines (steam engines) for the industrial revolution. Steam engines are heat engines. That is they thought in terms of input (heat in the form of fuel) and output (work). Both of these were thought of as 'naturally being' positive quantities. So they wrote their version of the Law of Conservation of Energy (The First Law of Thermodynamics) as ΔU = q - w. Chemists came to the scene from a different point of view. They wanted all forms of energy to have the same sign, whichever side of the conservation appearance they appeared so they could present the equation as a sum on both sides of the equation. So they wrote their equation as ΔU = q + w. By then it was also realised that, although all the terms are energies, there is a difference between ΔU , which is a state variable of the system, and q and w which are exchange variables of the energies crossing the system boundary. So they tidied up by stating that all energies crossing the boundary from the system to the surroundings are negative and all energies passing from the surroundings to the system are positive. Now they could add them up, move them about in equations and between equations in other parts of Science in a consistent manner. It is an improved system But it shows the importance of knowing the sign convention in use and the equations that go with it. This last remark also applies to other such instances of multiple conventions such as those in Electricity, Elasticity and elsewhere.
6 points
19. ## Last post of the first 1000

This is my 1000th post! Time to celebrate, This is a fine moment to open the Islay Single Malt I got for Christmas. Cheers from Ghideon, to all new and old form members!
6 points

6 points
21. ## My grand daughter!

My son holding my grand daughter!
6 points
22. ## The Border Wall or Fence

Implicit here is a false suggestion of equivalence. That’s not the case. If a kid walks down the hallway in school and gets punched in the face and has his lunch money stolen, is it his fault for carrying lunch money or walking freely down a public hallway? No, of course not, but if you think “both sides” need to compromise here then that’s precisely what you’re saying... that the kid is equally guilty as the bully. Trump last year said send a bill to my desk and I’ll sign it. Republicans were in control so drafted their version. Democrats agreed to vote for it and provide billions of dollars for this wall last year, and the compromise was that dreamers would get status. Trump backed out. He moved the goalposts. He said I want more. Funding ran out in December and Democrats said, fine... we’ll sign the republican bill yet again... we’ll compromise... but want money allocated to smarter enforcement options. A wall is not smart, and even countless republicans across the nation and some on Fox News itself agree. Trump said no. Eff you, a wall or nothing. Democrats said, Republicans still control all 3 branches of government. Since they’re in control, they need to get their president onboard. They couldn’t. President had a tantrum. Paper tiger in the Oval Office. Said he wants a shutdown. Shutdown began. Democrats took control of the house in January and on Day 1 passed a bill to reopen the government. Senate leader McConnell would not even bring it to the floor. Democrats later said they’d give more money for border protection, just not a wall. They compromised. President still refused. Wall or nothing. Eff the workers. Democrats passed multiple other bills to reopen parts of the government and agreed to negotiate terms on border security. They AGAIN voted for the previously passed republican funding bill from December. McConnel AGAIN wouldn’t bring it to the floor. Today Democrat senators continued to pressure McConnell to bring the bills up for a vote. He refused. He said it was pointless because the president won’t sign. Democratic Senators reminded him that they had the votes to override a presidential veto... that they are a co-equal branch of government and need to act like it. McConnell left. He just walked off the floor. Still no vote. Democrats will again pass a bill tomorrow to reopen the government. The bill will be the one drafted and previously agreed to by republicans. I agree there’s a lack of compromise here, but to say it’s equal across the aisle is absurd. The bully is trying to steal the lunch money. The other side has already offered to share their sandwich with him and are not at fault merely for having lunch money in their pocket.
6 points
23. ## What if Einsteins Definition of Simultaneity is incorrect?

Right, he is saying that the speed of light in both directions is the same with respect to any inertial frame as measured from that frame. So in the following example we have two observers. One standing along the tracks and the other traveling along the tracks in a railway car. Two flashes are emitted from two points along the tracks that are equal distance from the track observer. the light from these flashes arrive at the midpoint observer at the same moment as the railway observer is passing him. Thus both observers detect the light from the flashes at the same time. Like this: For the midpoint observer ( or anyone at rest with respect to the tracks) these flashes were emitted simultaneously, as shown by the expanding circles: However, for the railway car observer, events have to occur differently. He still detects the light from both flashes simultaneously, and they arrive when he is adjacent to the track observer. But unlike the track observer he has not remained halfway between the emission points the entire time. He is not an equal distance from the emission points when either of the flashes was emitted. But he must also measure the speed of light for each of the flashes as being the same relative to himself. But since the distances each of these flashes travel relative to him are not the same, in order for the light of the flashes to reach him simultaneously, they must have left at different times. And the sequence of the events for him occur like this: For the track observer, the flashes are emitted simultaneously, but for the railway observer they are not. This is the relativity of simultaneity: Events that are simultaneous in one inertial frame are not so according to another which in relative motion with respect to the first frame.
6 points
24. ## SFN's New Moderators Thread

I am pleased to now add CharonY and Strange to the list of gullible fools wonderful people willing to sacrifice their time for the greater good here at SFN. Congratulations!
6 points

6 points
26. ## Stephen Hawking Passed Away 3/14/2018

Stephen Hawking has passed away at the age of 76 on Pi day, 3/14/2018. http://www.bbc.com/news/uk-43396008 https://www.theguardian.com/science/2018/mar/14/stephen-hawking-professor-dies-aged-76?CMP=fb_us
6 points
27. ## Trump Effects

This is the rhetoric pushed by billionaires who don't need the government the way most of us do. Isn't it pretty obvious that the billionaires in politics today are only interested in removing restrictions on themselves, and limiting the money spent on the rest of us? These folks have been hammering this message of "bad government" and "sleazy politicians" for decades, while actively being the representatives with the sleaziest behavior, doing everything they can to make the government bad. They don't care if you have access to libraries, museums, parks, swimming pools, or healthcare. They have all those things taken care of due to their massive wealth, and object to taxes that make these things available to the rest of us. They've chosen to ignore our efforts that brought them great wealth, and instead spend money convincing folks that government needs to be dismantled for OUR good. And now they have this blatant racist sexual assaulter-in-chief who is morally and economically corrupt, and happens to have a deluded following all chanting about bringing down the Fed. Working class folks who think this billionaire has their backs while he whittles away at the very thing that has the best chance of making all their lives a lot better. The wolves have tricked the sheep into removing restrictive fences, and the sheep are all praising the freedom.
6 points
28. ## Why doesn't truth matter & middle ground

Puerto Rico agrees. Black athletes agree. The anti-fascist movement agrees.
6 points
29. ## God and science

Why do you limit your options to 'god did it' or 'everything popped out of nothing'? What about it didn't start, i.e. it's always existed? What about 'we don't know'? Also, as i understand it physicists have found that things do simply pop into existence. And yes, i'm frequently astonished by existence. Why does that imply god? I like this question. Many people seem to question that the universe could either just pop into existence or that it has always existed - but are happy to ascribe these exact same properties to something they call 'god'. Either way something has this property - why not discard the middleman and simply ascribe it to the universe. Depends how god is defined. A god that set up the conditions for the big bang but does not intervene at all thereafter would be impossible to detect, at least with our current capabilities. A personal god that answers prayers and parts seas has been pretty well debunked. Such a god would be easy to detect - we would just look for instances where the laws of physics contradict themselves (i.e. the rules change) - seas start to part, lakes turn into wine, whatever other crazy stuff you think a god might do. There is no sign of such a god.
6 points
30. ## Why is alcohol legal ?

We instituted a version of a safe zone in my household when my children were too young to drink. Coming home drunk was a violation of our rules, but if my kids were out with the car and under the influence, they could call home for a ride, 24 hours a day, with zero retribution for drinking. I was willing to accept law breaking and rule breaking if it meant saving them from harm. I suspect people who aren't willing to accept safe zones for drug use among strangers will usually feel differently if it is a loved one whose life is at risk.
5 points
31. ## Are there more than 2 sexes?

I think we can all agree that for the purpose of reproduction of the species ( human, that is ), only two sexes are needed. One is not enough, and three ( or more ) are superfluous. That doesn't mean that there are not people who don't fully fit into the male, or female, grouping; but for the criteria of reproduction, there is no third ( or 4th, or 5th ) category to place them in. One has to ask, then, what is the purpose ( or agenda, if you will ) for having more than the male and female sex classifications. Please explain. Thank God he's not Mexican, or you'd imply he was lazy. Or Oriental and a bad driver. Or Italian and a mobster. Can you see what is wrong with that line of thinking, Stringy ? I had hoped this thread had died, because I really don't like having people I consider friends call each other 'dicks', or make thinly veiled implications of transphobia, homophobia or racism, so this will be my only post on this thread. But I would like an answer ( I will still read ) as to WHY a third sex is needed, and what is the PURPOSE of the differentiation. Is more 'separation' really desirable to more 'inclusion' ? Is this just another social engineering exercise ? Is it to make some people, who feel 'different', feel better about themselves ? What am I not seeing ?
5 points
32. ## BLM, Capitol Riot, Hypocrisy and False equivalency -Split from: Blow to US Democracy

We can all agree that violence on either side is wrong and should be avoided. What we seemingly cannot agree upon is why so many feel the need to engage in whataboutism and mention a protest in favor of following our laws done in Portland with an insurrection on our democracy itself trying to dismantle our laws in Washington DC. Whether intentionally or not, this suggests an equivalence between the events which is false and which only distracts us from dealing with each separately, appropriately, and in accordance with our laws. Person A: Climate change is a major problem. Person B: What about covid?! That’s a problem, too. Me: Both are. They’re not equivalent. They’re not mutually exclusive. We must deal with both at once. Walk and chew bubble gum. Simply replace climate and covid with DC and Portland. This isn’t exactly rocket science.
5 points
33. ## FTL thought experiment

When you arrive at point C, you will see the same light coming from both stars as someone who never moved from point C; Light that left both stars 5 yrs ago. You see both stars as they were 5 yrs ago.
5 points
34. ## Examples of Awesome, Unexpected Beauty in Nature

Volcanic lightning is hard to beat. https://en.m.wikipedia.org/wiki/Volcanic_lightning Calbuco, The Awakening.” ... Calbuco Volcano is located in the lakes region south of Santiago, Chile’s capital city and is one of the 10 most dangerous volcanoes in the country. After more than 40 years of inactivity, the day April 23 the volcano erupts, spewing more than 200 million tons of ash https://www.dailytelegraph.com.au/news/photos/national-geographic-photo-contest-2015/image-gallery/a2afa2087ecd4f4d62475d231b129e31
5 points
35. ## Gravity

The 'bowling ball on a rubber sheet' is a two dimensional reduction of a 4 dimensional configuration. It has multiple problems, one of which is that you can observe it from an embedding third dimension. Space-time has no embedding dimension; both the bowling ball and you, the observer, would need to be intrinsic to the rubber sheet ( i.e. also two dimensional ). A three dimensional representation would already get rid of some problems, but not all. Picture a three dimensional grid, where x, y, and z axis divide up the space into cubic elements. A mass placed in this space would curve the x, y, and z lines such that the elements are moreskewed, and smaller, as you get closer to the mass. That is 'space' curvature, and one aspect of gravity, but already much harder to visualize than the two dimensional example of the bowling ball/rubber sheet. Actual gravity is four dimensional 'curvature' of space-time, and I can't help you visualize that as it is impossible. Some problems are just not suited to visualization, but understanding even just the basics of the math goes a long way to clarifying things.
5 points
36. ## Today I Learned

Today I learned that skills improved by participating here on scienceforums can, at least in some minor way, be helpful in the current virus situation. I joined a local initiative where students studying from home can ask about math and physics. Debating science here has made me more confident regarding mainstream science and how to respond with useful hints (instead of solutions) to homework questions.
5 points
37. ## How can the cosmos be eternal?

A better question is why $10^{-43}$. Would it help to recognize that number is one unit of Planck time with our current observable universe to the volume of 1 Planck length. The temperature being equivalent to Planck temperature. The Planck units are in essence boundary conditions on which our ability to mathematically describe in essence breaks down into Infinities and nonsensical results. You often only hear the space and time axis in essence flipping roles for the GR descriptive but cosmology must also include both macro and quantum effects. So its good to understand how the limits of the macro and quantum theories apply. (String theory also recognizes these limits) One detail as mentioned in this thread is were describing our Observable portion in essence the limits of shared observable causality with our current universe. Time being a measure of rate of change or duration you in essence need a dimension in order to have something to measure or even something that must be able to change. However one must also realize that the t=0 represents the collective worldlines of all particles in our observable portion extrapolated from the closest we can mathematically describe and potentially measure. In the closest to pointlike we can describe. It does not represent any time outside our region of shared causality. In essence $10^{-43}$ is the origin of time for all potential worldlines in our observable universe that are extrapolated to the beginning of our observable universe (as the emitter event).
5 points
38. ## Sorry about the downtime -- we're back!

Fake news! It was a perfect renewal! Absolutely perfect. In a world where even my fridge can give me reminders, I still managed to forget. Luckily Capn was able to social engineer his way through my answering service who sent a page out to me stating "CAPN REFSMMAT - RE: WEBSITE". They even listed a hospital he was calling from 😂. I wasn't on call today so when I heard my answering service text me I about lost my mind until I saw who it was.
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39. ## What if you fall through space time?

No. Space-time should not be comprised of anything like dough. It is not substance-like at all. The concept of space-time is just the recognition that the measurements of space and time are frame dependent and not absolute. The analogy is that in Newtonian physics, space and time are treated like North/South vs. East/West. In such a situation everyone, no matter what direction they are facing, all agree on these directions. Everyone, for example, agrees that town A is 40 miles North and 30 miles East of town B. However the Space-time manner of treating this is that each person uses his own sense of Left/Right and Front/Back. Thus one person facing one direction will say that town A is 30 miles to the left of and 40 miles in front of town B, while someone facing in another direction would say that town A is 50 miles directly to the right of town B. It makes no more sense to think of space-time as being "substance-like" than it would to think of Left/Right-Front/Back as being "substance like". Now I also realize that in GR, it is said that Space-time "curves" in the presence of mass. And to many people this implies space-time being a "structure or substance". This is not what this means. "Curvature" of space-time really just means that the geometry rules governing it are non-Euclidean. In other words, the rules of plane, Euclidean geometry just don't hold.
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40. ## The 11 dimensions of string theory

Glad to be back had some RL issues which are done with now
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41. ## Members in the Mod Queue

thethinkertank has been placed in the queue for spamming the forum with an impressive amount of nonsense.
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42. ## How to disprove these creationist claims?

It's pretty easy, and it's been done to death. Most of their arguments are strawmen, in that they make a false or misunderstood claim to attack, instead of a more difficult, legitimate claim. For instance, that the creation of proteins is astronomically improbable, therefore it couldn't have happened. Since they mistakenly think the universe is only a few thousand years old, they can't accept that evolution had millions of years to miss before it finally hit. Many of the arguments are nitpicking Darwin, as if the theory began and ended with him. They ignore what every scientist knows, that theories are dynamic, changing as new evidence shapes them into better and more accurate predictions. And they keep repeating arguments that have been refuted, which is seriously dishonest from an intellectual perspective. I still hear "If we descended from monkeys, why do we still have monkeys?" being spread to ignorant audiences. They study evolution only enough to cherry-pick the parts many don't understand, and then ask questions they don't want answers to. If they really studied evolution sincerely, with an open mind, they would come to the obvious conclusion that there's no other way it could work. Evolution is a fact, and the Theory of Evolution describes how it works, with observational accuracy backed up by more evidence than almost any other theory.
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43. ## The Border Wall or Fence

Trump has relentlessly insisted for 3 and a half years that Mexico would pay for a border wall. No nuance, no doubts, no maybes, Trump said Mexico would pay for the wall. He held rallies a;; over the country leading people in chants where he'd say "who's going the pay for the wall" and stadiums full of supporters when yell "MEXICO". Trump has given interviews and briefings where he'd cut reporters off and insult those who challenged how he'd get Mexico to pay. Now here we are with the govt shutdown as Trump demands a newly elected House majority give him the money tax payer money for his wall......and some people are actually trying to launch arguments blaming Democrats .
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44. ## Serial abusers of the reputation system

In previous threads, staff have mentioned that we have on occasion curtailed or removed the ability for people to use the reputation system. In previous versions of the forum software we were able to limit positive or negative reputation limits separately. This meant that the impact of people who wished to use the reputation system to target specific members was always low, and staff could easily reverse it. This no longer being the case means that the system is more open to being abused by people wishing to use it as a form of personal attack. Thankfully, we have had very few cases where staff have had to intervene. For those cases where we have had to do something, admin have created two new member groups with reputation point limits set to either 0 or 2, which limits the use of both positive and negative rep points.
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45. ## B Kavanough and MeToo

People are starting to argue with reputation points. I see more and more negatives, on both sides, even for valid points which deserve deliberation. It is a very sensitive subject but, I have come to know that everyone involved in this discussion is a sensible person. Discussion leads to understanding, so if you want your viewpoint understood, discuss it. Don't neg rep opposing views, they're just trying to make their viewpoint understood.
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46. ## Non-locality

It is difficult to explain why you are wrong because you don't understand the subject and so you just reject the explanations (this has been true in all of your threads). And yet you are the one who constantly quotes the words of others but ignores the science. For example: Dalo: I don't believe X Others: Here is a simple explanation why you are wrong ... D: That's a bit vague, can you be more specific? O: <detailed explanation with evidence and a mathematical analysis> D: I don't need all that maths and what about [irrelevant sidetrack] O: What exactly are you asking? D: How dare you! O: I'm just trying to clarify D: I don't believe Y, as I have been saying all along O: So you have changed the subject D: No, you keep introducing P and Q, but I want to talk about Z O: OK. Do you understand <basic schoolboy physics>? D: Why should I have to? If you can't prove me wrong ... O: <collective sigh>
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47. ## Time Does Not Exist

Ironically, under the title “time does not exist” it says “posted three hours ago”.
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49. ## Banned/Suspended Users

scherado has been banned for multiple instances of rule-breaking in his quest to become the Troll King. We apologize that his interruption in the normal rational discourse was all noise and no signal whatsoever. Roger Dynamic Motion has been banned, NOT for incessant hijacking and almost daily irrationality, but for failing to respond to requests for clarity, EVER. Discussion requires that we express our ideas so others can understand. We wish him good luck with his ideas, whatever they were supposed to be.
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