exchemist

20 minutes ago, abdullahrana3089 said:

While I cannot really comment on the physicist part, I would like to add that one should have realistic expectations regarding potential research positions, especially if one is interested in a particular field. Pubg Name Generator There are not a lot of permanent research focused positions out there (and those that are are disproportionately competitive). So it is good to keep that in mind and look for career paths early on.

 

Hahaha. “Pubg Name Generator” is something of a giveaway.😀

On 8/14/2023 at 6:03 AM, npts2020 said:

Citation? I was always under the impression that stress caused slower growth of all types of hair due to increased corticosterone levels hindering that growth.

 Grimm J & Grimm W : Rapunzel .

10 hours ago, poolesa said:

In the realm of academic research, citation counts and references to authoritative sources are often used as indicators of a paper's credibility and impact within a particular field. However, as you rightly pointed out, citations don't necessarily equate to validation or agreement with the content of the paper. Citations can encompass a range of relationships, including critiques, responses, disagreements, and extensions of the original work.

It's important for researchers and critical thinkers to strike a balance between respecting authority and exercising a healthy degree of skepticism. While relying on established experts and reputable sources can be a practical approach, it's also essential to engage in critical evaluation, open inquiry, and independent analysis when warranted.

Yes. We also need to keep aware of low quality, predatory or pay-to-publish journals, like those published by SCIRP for example. These are a new disease that has spread to an alarming degree among science publications. Caveat lector indeed. 

3 hours ago, Genady said:

There are two traffic related threads going on right now, and here is a traffic related question which would've been OT in both, so I post it here.

The points A and B are connected by two roads, APB and AQB.

The section AP takes 20 minutes regardless of traffic. The section PB takes time equal to T/10, where T is the number of cars on the road. For example, if there are 200 cars on it, it takes 200/10 = 20 minutes.

Similarly, AQ takes T/10 minutes and QB takes 20 minutes regardless of traffic.

The city planners came up with an ingenious way of connecting points P and Q with a road that does not take any time at all regardless of traffic:

How will it affect the average time of travel from A to B?

Don't tell me, the road PQ goes over a bridge, at a place called Wheatstone. 😀

16 hours ago, Photon Guy said:

Sometimes in science fiction they have planets that have very strong gravity and as a result the people from such planets are really strong. For instance, people from a planet that has twice the earth's gravity would be able to perform tremendous feats of strength while on Earth or while on any planet or environment that has gravity around the same level as earth's gravity, able to bend steel bars and lift cars and so forth. Im wondering though just how realistic that would be in real science. Let's say Earth did have twice the gravity, would we all evolve to be super strong? Or is that just in science fiction and not in real science?

This is explored in Hal Clement's "Mission of Gravity": https://en.wikipedia.org/wiki/Mission_of_Gravity  which I read as a teenager and was much impressed by. His solution was small, compact beings. 

23 minutes ago, Phi for All said:

I couldn't find it quickly this morning, but a few years back there was a meta-study on traffic which concluded that virtually ALL modern traffic was caused by brake lights. You see people brake ahead of you and back off the gas, or step on your own brakes, continuing the signal back down the line to remove energy from the system. And most of the brake lights could be avoided if folks backed off and stopped tailgating, which would allow for more merging to smooth the flow.

MY hypothesis is that if more people practiced cooperative driving rather than competitive driving, we'd all make it to work/home/wherever more consistently.

I’ve certainly read that if a certain distance is not maintained, one vehicle braking will cause the one behind to brake more sharply, due to human reaction time, and several vehicles back you have them resorting to a full emergency stop in order to prevent collision. So the braking wave is progressively compressed, eventually into what amounts to a shock wave. But I’d like to see a summary of the effect referred to in the OP, as I’m still not clear what we are discussing.

54 minutes ago, Steve81 said:

Sorry, I’m still obviously new at this. If you could point me in the direction of a hypothesis you feel is particularly well written / in the format you’re looking for, I can aim to use that as a template.
 

Well you refer to an "effect"  but without describing it. Just describe what the effect is on which you are building your hypothesis. (One of the forum rules is people should be able to follow a discussion without being sent off-site to other links. So a précis of what the MIT link says should do the trick.)  

On 8/13/2023 at 4:23 AM, Steve81 said:

MIT did a study a while back regarding tailgaiting and traffic jams. I can’t seem to find the actual report, but it appears looking at the graphic that the analysis was confined to a single lane.

My hypothesis is that this effect is compounded in a multi-lane scenario, based on my observations driving in DC traffic. An additional source of trouble here may be people that are obligated to change lanes, but have to wait for a gap in traffic, thus slowing down their lane. The tendency of people to try and switch lanes to the faster moving lane may also exacerbate the issue.

I would also expect that a sudden unsafe lane change (cutting someone off) could exhibit similar effects, as the driver being cut off is forced to brake, sometimes significantly so.

This sounds a bit like the kinetic theory explanation for why the viscosity of gases increases with temperature.🙂

6 hours ago, kenny1999 said:

My beard normally grows slowly and I like to keep checking, most of the time I don't find any new beard after 2 or 3 days of complete shaving. However, one day I was very stressed, angry and depressed and then I could find new beard only one day after shaving. I wonder if rate of beard growth largely relate to stress?

There seems to be a link between sleep and rate of beard growth: https://pubmed.ncbi.nlm.nih.gov/3442272/

I’m not sure whether this might indicate any link to stress though. 

13 minutes ago, TheVat said:

Scopus is also good for citation count.  Bear in mind, though, not all citations mean validation or approval of the paper in question.  You could have cites that say basically James Clemens got it wrong and here's why...

Which all serves to remind that Appeal to Authority (argumentum ad veracundiam) is a logical fallacy.  Even someone who's a Nobel prizewinner in their field can be mistaken and fool themselves.  For fun, google Francis Crick claustrum hypothesis.  

Well, yes and no. It may be a formal fallacy in philosophical argument, but in day to day life reliance on authority is something we all practice, much of the time, in order to get on with our lives without challenging every bloody thing from first principles all the time. Anyone who takes articles published in Nature, or on the BBC, as likely to be sound is relying on authority, viz. the reputation of a well-regarded source. Whenever we learn a theory in science we rely on authority, in the form of the books or the lecturers we follow. We take things on trust, from recognised authorities. We have no choice. 

17 minutes ago, DanMP said:

I understand what you mean (I am also "redshifted" 😛), but still, this forum is much better than physicsforums, where the moderators are very quick to close the topic, or restrict your right to write in it, when you insist asking uncomfortable questions. Just search/see my activity there. They are like a Physics Inquisition. This is not the case here.

Regarding this thread, I believe that your misconception was to consider the balloon analogy with the Earth in the center ... Consider the Earth as another point on the surface of the inflating balloon and you will understand the responses you get.

 

I also have some questions and observations regarding big bang theory:

When they assessed the time from big bang, what reference frame they used? There is no absolute time.

Just after big bang, the mass was confined in a small volume, yes? We know from GR that the clocks are slower when they are situated in/near a place with high density. Also light originating from such a place would be redshifted. Was this redshift considered (subtracted) when the speed of expansion was calculated? 

Last but not least:

 

 

One thing to bear in mind is that light only started travelling through dark space from the surface of last scattering, 380,000 years after the Big Bang, by which time a great deal of expansion had already occurred.   

1 minute ago, Genady said:

As within any social group, e.g., gangs, fraternities, sororities, meditation classes, etc.

Yes, you have anticipated my reaction too. "Society at  large" comprises a mix of the views and attitudes of all the many groupings that people belong to, religious adherence being one.  But, of all of them, the grouping that most overtly propounds a view of what constitutes moral values and behaviour is probably religious affiliation.  

3 hours ago, Steve81 said:

This is a carryover of thoughts from another thread regarding human development, the integral part shame plays in it, combined with the evolution of enlightened philosophies. Relevant quotes about how shame is related to our development are from Building Self Esteem by Joseph Burgo, Ph.D. Since I've been accused of spamming the book, I'll refrain from posting a cover shot. I will include the relevant page at the end.

Inferring from the book a bit, human development has relied upon shame-driven human behavioral modification, combined with societal advancements with respect to enlightened philosophies. This presents a problem as it relates to religion.

As you all are surely aware, religions tend to be slow to change (if they change at all) their guiding philosophies. The world's major religions are over a thousand years old, and while the Catholic Church as an example has evolved from the bad old days of the Spanish Inquisition, it remains well behind the times on a variety of topics (gay marriage and abortion to name a couple big-ticket items). Fundamentalist Islamic societies are even worse, the Taliban as an example (women's rights anyone?).

The implication here is that devout followers of these religions will follow that outdated moral code, and that will be their basis for feeling shame. While something may be deemed a gross violation of human rights by our standards, by theirs, it's just the way things are supposed to be. They may literally feel NO shame when engaging in bigotry, because they aren't programmed to do so. Moreover, given the fanatical adherence to dogma that some of these individuals exhibit, there may be no feasible way to change their minds.

 

 

 

I'm sure there is a lot of truth in this idea of shame. I'd be intrigued to know where the author thinks the concept came from, from an anthropological, or evolutionary, point of view. Shame does seem to inform a far amount of the thinking in the more fundamentalist branches of the Abrahamic religions. But I'm not sure how much of a role it  plays in, say, Buddhism or Hinduism. Does the author claim it is fundamental to all religions or just to those most widespread in "western" cultures ?  

It's also worth pointing out out that even in the Abrahamic faiths, shame plays a fairly subservient role nowadays. In Christianity the concept of sin remains central, but I'm not convinced that sin has a one to one correspondence with shame. Does the author talk about the concept of sin, or would that be too theologically specific to one faith? 

2 hours ago, imstillcurious said:

More specifically, I am confused about why the increased underwater pressure would have an effect on the internal pressure in a person's body.  Idk maybe I'm an idiot and the answer is too obvious for most people to ask, but hey here I am! 

The solid tissues of your body are flexible, apart from the bones. So your body cannot prevent the ambient pressure from compressing it.

However, since most of your body is made of liquids, mainly water-based, and as liquids are virtually incompressible, what happens is the compression does not deform your body when the pressure goes up. However all the fluids in your body become pressurised, to the same pressure as the ambient environment.

The exception to all this is the body cavity of the lungs, which is filled with gases. These most definitely do reduce a lot in volume when the pressure goes up. So if you were not given compressed air to breathe, your lungs would be collapsed by the water pressure and you would asphyxiate. The pressure regulator in SCUBA gear adjusts the pressure of air you are fed from the cylinder so that it is equal to the pressure of the environment, i.e the water pressure at whatever depth you are. This is also the pressure of all the fluids in your body.

So your blood is at the same pressure as the water and so is the nitrogen in the air you are breathing. At higher pressure your blood dissolves more nitrogen than at atmospheric pressure and if you ascend too fast from great depth it does not have time to come gradually out of solution and be breathe out through the lungs. So you can get bubbles - and then you have a bent diver on your hands.  

3 hours ago, Steve81 said:

I’m was countering the implication that diabetics represent a tiny fraction of hospital patients. Given the 11/100 ratio you provided, combined with the fact that we spend more time in hospitals, that seems unlikely to be true, depending on one’s definition of tiny of course.

I’d also note that a balanced diet relatively low in carbohydrates benefits more than just diabetics as well. It’s not a cure all by itself of course for things like heart disease, but it certainly doesn’t hurt. The South Beach diet was developed by a cardiologist after all.

I do agree with the issues of a for profit medical system. The fundamental issue as I see it is, what wouldn’t you pay to save your life?

I'm an outside observer on this, being in the UK, but it seems to me the basic problem with the US health system is that it is what is called a "broken market". The consumer has no leverage over the supplier and thus it is not a suitable subject for market competition to deliver an efficient outcome. As I understand it, most people in the US get health cover as part of their employment remuneration. The employer pays a charge to an insurer, who adds a mark-up to the charges it receives from the medical providers. So the end consumer of health treatment is 3 steps away from the provider and has no market power. Nobody in the chain has either the incentive, or the purchasing power, to shop around and drive down costs to keep the providers honest. In theory the insurer might have such an incentive, but in practice it is easier just to accept the charges, pass them on to the employers, with a mark-up, and get out on the golf course.  

In most other countries there is central purchasing of health provision by the government, by means of large and valuable contracts, professionally negotiated, and hard bargains can be driven. But that involves a role for "government" - which is anathema to all the American rightwingers, brought up  on the myth of individualism and Ayn Rand.   

1 hour ago, Genady said:

The odd behavior of a subatomic particle may shake up physics (msn.com)

There's a bit more information here: https://www.ucl.ac.uk/news/2023/aug/new-measurement-particle-wobble-hints-new-physics

Seems it all revolves (haha) around the g-factor for muons, which, by making them precess in a magnetic field, has been found to be 0.2ppm (!) stronger than predicted by the Standard Model. So a technical tour de force in terms of measurement and a very tiny difference, which nevertheless is said to be statistically significant, at the 5σ level. This is a replication of earlier results, but with more data behind it.  

2 hours ago, studiot said:

 

I'm sure we are all well aware of at least the basics of how insurance works and that it can work for both many socialist (in the broadest sense) and non socialist societies.

 

 

Actually I'm trying to find some solid foundation to this thread which has the makings of a good topic, but seems to me to be floundering around all over the place.

It's your thread.

 

Perhaps we could examine societies for which 'socialism' presents special difficulties ?

For instance take the Modern day Outback or the pioneering North America.

Self reliance was /is possibly the greatest virtue where folks live hundreds of miles from the nearest neighbour.

Or societies that relied on slavery. Is there any point insuring your 'asset' if there is a ready supply of replacements ?

 

 

 

I don't think it is floundering particularly. As @iNow observes, risk pooling is the basis of a number of collective systems in societies.

National Insurance was the original basis of the UK's welfare state, cast in its present form by Attlee's government, which was of a distinctly socialist persuasion. (It's hard to think now that even road transport was nationalised by that government.). 

I think there's a productive discussion to be had about the way socialist ideas can be, or have been, adapted over the years, bearing in mind some of the excesses of corporate capitalism that we have seen in the last decade or two. 

1 hour ago, mistermack said:

No, but they've done a great job of dodging it.

OK, maybe I've got it: are you referring to the Early Twentieth Century Warming (ETCW)? Is that what you are concerned about?

There's a paper here on it: https://wires.onlinelibrary.wiley.com/doi/full/10.1002/wcc.522. This seems to attribute 40-50% of the change to human-induced effects and the rest to a succession of other climatic events. But indeed it looks as if this is still not fully understood and that research on it continues.

From what I have been able to find so far, the CO2 concentration in 1950 seems to have been 311ppm, versus 300 in 1900 and 285 in 1850. I think I read somewhere that early CO2 increases may have been offset by cooling due to aerosols and soot in the early industrial revolution. So there seems to have been a slow increase going on throughout the c.19th and into the very early c.20th, but possibly with no apparent effect. What I'm unclear about at the moment is whether the greenhouse effect is expected to be linear in CO2 concentration or not.    

1 hour ago, Steve81 said:

My thought is that such insurance would apply to ventures where risk is unforeseeable, such as new medication. Pollution is already well understood (unless we discover something new), so insurance wouldn’t apply there.

In the case of drugs especially, the FDA certifies the drug as safe for use, so I would consider them equally liable if it isn’t. And of course the drug companies would be paying into the insurance system, so no free rides. Might have to propose this to my congressman 😂

Yes that's fair. And in fact I think that sometimes happens, in cases where a risk was not reasonably foreseeable by the company that made the product. 

1 hour ago, Steve81 said:

One potential way to mitigate this going forward that I can think of is to essentially have some sort of insurance system to help clean up the mess. On a large industrial scale, given the potential costs involved, we would likely have to rely on government for this. If the government deems something uninsurable, it doesn't get done. Of course, who makes that decision, and the potential for abuse there is also a possible issue. Funny how the weak link always seems to be humanity.

It seems fair though that the polluter should pay to clean up his own mess, does it not? I'd be averse to a system whereby private enterprise can pollute with impunity and the taxpayer has to pay for the clean-up.  One wants the incentive not to pollute to be with the enterprises that may be contemplating polluting activities.  If they know they may be held liable, they will do their due diligence on pollution hazards before they start their operations. That is more or less how it works today, imperfect thought it is. 

50 minutes ago, mistermack said:

You've ignored the points I made. I'll ask directly, is it honest to constantly quote temperatures from the start of the 20th century, when any GW resulting from manmade CO2 can only date from around 1950 ? ( or more likely 1970, there would surely be a delay in temps responding to a CO2 rise) And why do the GW people feel the need to mislead in that way ?

As far as the trends go, I would point out that the red arrow HAPPENED (if the graph is right). If you started measuring in 1910, and kept going to 1945, you would measure that rise of 0.6 deg in 35 years. It's not imaginary, and does resemble the latest rise, that's been attributed to CO2. You can't ignore it, by saying it was followed by a fall, or preceded by a fall. It's still a real rise that happened, and it can't have been due to CO2 levels.

I'm not claiming that it's conclusive of anything. It just weakens the case that CO2 is responsible for ALL of the rise since 1950. You might fairly claim that it's likely, but to claim near 100% certainty, as the IPCC does, is stretching the truth. 

Nobody claims the difference in temperature between the dates you mention did not happen.

Nor does anyone claim that particular difference in temperature was 100% attributable to a man-made greenhouse effect. 

2 minutes ago, Steve81 said:

With respect to pollution disasters, I'd think of it like this: when humans invented coal fired steam power, they simply didn't know enough about the pollution byproduct to consider that. Humans got hooked on the benefits the new technology provided, and by the time the pollution costs were realized, it was too late to do much about it except try and innovate again. 

This applies to many things. A medication can undergo years of testing, get FDA approval, and then years later be discovered to have some horrific side effect and have to be pulled from the market. The problem is, we don't (and can't) know everything at inception.

True. (Our use of fossil fuel and consequent dependence on it today is the perfect example of that.) But that's why we need mechanisms that learn from experience and apply corrective action. Markets generally won't do that, or not until so much damage has been done that sales are lost from angry consumers. One needs regulation, by an expert non-profit body, supported by the political system so that citizens can see why it is needed -  and that it is not just dedicated to depriving people of "freedom". 

22 hours ago, mistermack said:

What I'm criticising is the constant portraying to the public of MMGW as starting from the late 19th-early 20th century, when any climate scientist would know that CO2 levels didn't start jumping in any significant way till about 1950, the year I was born. I think quoting global rises from before then is deliberately misleading. In the public mind, one deg celsius isn't a lot, so it's just a way of getting over the one degree mark.

Here's the same graph, with the two major rises arrowed by me. I'm saying that to honestly portray the amount of warming that can be assigned to CO2, you can only use the second rise, the black arrow. And also, how can you ignore the fact that the first rise happened without CO2 being significantly raised? And why should the rise shown in black ALL be attributed to CO2, when something similar already happened previously?   

But this is ad-hoc cherry-picking, rather than a scientific approach to what the data points indicate. Earlier in the thread @Ken Fabian posted a curve showing the effect of LOESS (or LOWESS) smoothing on the data. I looked that up and found this description: https://www.statisticshowto.com/lowess-smoothing/

That, surely, is the statistically correct way to go about looking for underlying trends. It makes sense to include a good data set from before the suspected influence starts to manifest itself, in order to see whether there is any kind of baseline, from which the trend starts to depart. 

4 minutes ago, Steve81 said:

Well I suppose that depends on your target audience. To someone with a doctoral degree in physics, Newton's laws might not be food for thought. For a man with only passing knowledge of physics, they might well be interesting.

I'm happy to discuss the challenges we face with capitalism today (not accounting for externalities like pollution, discrimination preventing market access, and so on). However, I'd just assume do so with someone who approaches things in a constructive manner.

I don't think I would treat pollution, and other environmental negative impacts, as an externality. It's sort of interesting in that both state-run and market-run systems produce pollution disasters. In both cases the problem really comes down to lack of public knowledge and public accountability. I suppose, at the end of the day, what we all want from an economic system is one that innovates and thus creates wealth, for us all to share in some measure, but is accountable to us as consumers and as citizens. The political debates are all about how best to do that.  

2 minutes ago, Steve81 said:

I'm somewhat confused by your confrontational tone. I didn't imply that my observations were groundbreaking in any way. Further, my post was quite obviously limited to a discussion on socialism itself, not mixed economies or the many flaws of unregulated capitalism. Basically, you agree with the point of my post, but you decided you needed to confront me all the same. Good for you. 

If I were to post Newton's laws of motion and then sign off with "Food for thought", I'd expect a bit of criticism.  

Yes I agree with your points, but it is all conventional stuff. I am suggesting it would be more interesting to think about the economic challenges of today than go over old debates, long since decided.