I wonder if any of the more scientifically minded people on here could help me, please.

[Chris Koziarz]

Of course you deserve thanks. I asked a question. You answered it for me. I understand now. You made a simple spelling mistake. We're all human. We make mistakes even careless ones sometimes. You're being a bit harsh on yourself here. Forgive yourself. You don't have to apologise. (I know this sounds a bit rich coming from me.)

Thanks! Max is not among us, so my apology was empty anyway. For you to better understand my emotions surrounding it, let me qualify it now: it was a bit of pompous courtesy that we often use in correspondence. Sometimes we want to "soften" our expression of remorse or happiness or other emotions, that at face value may sound silly or inappropriate, or too serious. I wanted to express desired pompous aspect by classifying my apology as "erratum". Should have had laughing out, ergo much softening effect, and did it really?

 

[Horsa]

Thanks! Max is not among us, so my apology was empty anyway. For you to better understand my emotions surrounding it, let me qualify it now: it was a bit of pompous courtesy that we often use in correspondence. Sometimes we want to "soften" our expression of remorse or happiness or other emotions, that at face value may sound silly or inappropriate, or too serious. I wanted to express desired pompous aspect by classifying my apology as "erratum". Should have had laughing out, ergo much softening effect, and did it really?

You're welcome. I get you now. I didn't quite get that but since you explained I do now so I am laughing now. Haha!

 

[mrzz]

inside the sun
Great responses, mrzz.
It's my turn to contribute to the answers, as much as my knowledge goes.
1) What is low energy applied nuclear physics?
As you noted, it's abount practical nuke applications. MRI, as you recall is indeed "practical" and can be called "low energy" according to your definition, because to describe radioactive decay of an isotope used in medical imaging here, we don't need relativity theory. But the fact MRI process is "low energy" is rather obvious, a name "applied nuclear physics" would be sufficient. So this example does not illustrate, why a specialised field in question was created to start with.The answer to this latest question is: since we understood the reaction within the sun, we wanted to recreate it in controlled conditions, without a need for high energy input, thus benefiting from thermonuclear energy right here in our hands, and not 150 giga metres away. Without high energy input, it meant that the "artificial sun" would be cold (possibly even at room temperature) rather than as hot as a real sun (million degrees). The idea was called "cold fusion":
https://en.wikipedia.org/wiki/Cold_fusion
As you can read, various apparatuses have been created with various chemical compositions, where the researchers have claimed to obtain Helium from Deuterium fusion (the same reaction as inside the sun) but with only few eV (electronoVolt) per nuclei energy input (some pressurisation I guess). Deuterium is "heavy hydrogen" with an extra neutron in addition to the proton. Water composed of Deuterium is also called "heavy water". Typical "hot" nuke reaction such as Deuterium fusion inside the sun requires several MeV energy input per nuclei. As you can read in the above wiki, the very first claim to obtain Helium from heavy water came in 1989, so almost 30y ago. But the experiment failed to reproduce. Since then, "Cold Fusion" term feel into disgrace, their researchers found harder and harder to obtain grants. Eventually, they decided to rename their specialised field to low-energy nuclear reactions or condensed matter nuclear science and herein is the answer how the field in question came about. In general, it deals with nuke reactions where energy input is up to few keV per nuclei. It's quite an obscure area today (only few hundred researchers) and they may not recreate deuterrium fusion at room temperature but who knows, they may find out some other nuke reaction that will bring virtually unbound, and revolutionise the global energy production.

2) What is the difference in scale between nuclear physics & low energy applied nuclear physics, please?
I've already answered it above. Tpical nuke reaction involves order of MeV energy input (the same order as the energy output, output should be more if we want to source our energy from it!), while "cold Fusion" researchers are trying to excite nuke reactions with just few eV (unrealistic IMO), up to say few keV (more realistic)

3) I cannot add anything to your answer. Thank you!

Computer scientist, aham... It is a pleasure to meet you. I am Santa Claus.

P.S. Thanks a lot! Density of information of this one was quite high so I needed to visit it back today.

Question 2. You're saying that it is a difficult job to quantify the difference.

It is a fair bit more complicated than that. What was missing on my answer, and is implicit in Chris' very informative post above, is that we roughly speaking use different theories to explain what happens in the low and high energy ranges. I will give a gross exaggeration to make a point clear:

Suppose someone finds a lot of animal fossils, a lot empirical data and an existing species of animals, lets say some colorized zebras living hidden somewhere, that would somehow fit in Lamarck's theory of evolution. So if one would want to explain the evolution of all the equines, one would need both Darwin and Lamarck's theory (that are contradicting between themselves). The low/high energy threshold in nuclear physics is, at least to some extent, like the above example.

 

[mrzz]

All I can say is I agree. You are great science communicator, mrzz.

Thanks a lot. I really mean it, specially considering that I learn a lot from your posts.

 

[Horsa]

Computer scientist, aham... It is a pleasure to meet you. I am Santa Claus.

P.S. Thanks a lot! Density of information of this one was quite high so I needed to visit it back today.



It is a fair bit more complicated than that. What was missing on my answer, and is implicit in Chris' very informative post above, is that we roughly speaking use different theories to explain what happens in the low and high energy ranges. I will give a gross exaggeration to make a point clear:

Suppose someone finds a lot of animal fossils, a lot empirical data and an existing species of animals, lets say some colorized zebras living hidden somewhere, that would somehow fit in Lamarck's theory of evolution. So if one would want to explain the evolution of all the equines, one would need both Darwin and Lamarck's theory (that are contradicting between themselves). The low/high energy threshold in nuclear physics is, at least to some extent, like the above example.

Thank you very much for your answer, @mrzz.

I understand now. I love your example. Thank you very much. (I know how contradictory these theories are. I learnt about Darwin at school but read about Lamarck in 1 of the books Dad brought home for me to read 1 day when I asked him a question.)

 

[Chris Koziarz]

Computer scientist, aham... It is a pleasure to meet you. I am Santa Claus.

My equal pleasure, Santa.
Unlike you, I've been totally serious here. I explained in another threads, that my official degree not withstanding, my interest in climate science forces me to learn (or remeber from uni minor courcesw) things in many fields. But by necessity, any knowledge must not be very deep if it appears very broad (according to Bohr's philosophy we discussed earlier), and so far we haven't been discussing anything that hasn't been mentioned in my minor uni course in physiques. I expect you and other experts would have more to say than I do here if we descended into details.

 

[Chris Koziarz]

Thank you very much for your answer, @mrzz.

I understand now. I love your example. Thank you very much. (I know how contradictory these theories are. I learnt about Darwin at school but read about Lamarck in 1 of the books Dad brought home for me to read 1 day when I asked him a question.)

I don't remember the difference between Darwin and Lamarck (probably no one ever explained it to me), can you explain it in simple terms here for my benefit?

 

[mrzz]

My time to ask a question, kind of directed to @Chris Koziarz since he manifested his interest in climate change, but obviously everyone is invited to contribute. There is, of course, a lot of political implications in this discussion (which just blur the discussion itself) so I hope we can stick to the point here.

Let me play the devil's advocate and raise the usual counter-argument: accurate data is still very limited to reach a conclusion (at least direct data). This has some truth in it, we are indeed talking about processes that have a time-scale which is quite larger than the data horizon of reliable data we have. I can guess the nature of a few answers to this argument, but I am interested in reading them in full.

Also, I would guess (it is really a guess given my ignorance, not just an euphemism) that "climate change" is one thing, while "global warming" is another (which is one counter-argument against what is above).

By the way, I haven't asked the question yet: how close we are, or can we be, to consensus about climate change?

 

[mrzz]

My equal pleasure, Santa.
Unlike you, I've been totally serious here. I explained in another threads, that my official degree not withstanding, my interest in climate science forces me to learn (or remeber from uni minor courses) things in many fields. But by necessity, any knowledge must not be very deep if it appears very broad (according to Bohr's philosophy we discussed earlier), and so far we haven't been discussing anything that hasn't been mentioned in my minor uni course in physiques. I expect you and other experts would have more to say than I do here if we descended into details.

Sorry if it sounded rude, I just wanted to jokingly stress that you really speak with authority about the field (nuclear physics). It is not my exact field of expertise, but in all my years at the university I was always inside a nuclear physics group (although studying related fields), so the basics and the standard parlance I know. I have seen nuclear physicists from all over the world and I can tell you that you not only apprehended 100% that you got in your uni courses (which usually is a lot, we just need to check back in our old books to realize how much is there), but you probably added a lot to it independently. It is not the information itself, it is what certain questions are triggering in your answers.

By the way, you have raised the fusion subject, and the main reason I haven't replied was that I thought "there is hardly anything I can say here that this guy does not know already". But there are other posters/readers who could find it interesting, so maybe we could in fact open a thread about it.

 

[Horsa]

1 of these questions isn't quite a science question but the other is. I wonder if anyone can help me please.

1. Does the family name for the group of animals including horses, ponies, zebras, donkeys & mules equine or equidae come from the modern horses scientific name equus caballus or 1 of the horses ancestors equus sylvestris, please?
2. 1 of the horses ancestors equus sylvestris had 66 chromosomes. The modern horse equus caballus has 64 chromosomes. What happened to the other 2 chromosomes, please?

I've just realised that I'd have been able to answer question 1 before-hand if I trusted my own judgement more & reading the book that made me ponder these questions while waiting for a train I realised that I'd got some of the information the opposite way round. I'm over-due an eye-test & haven't been sent for it yet & my eyes are playing me up.

1. The name of both the horses ancestor & domestic horse which I mentioned came from the animal group name as the horse had lots of ancestors & branches of the same family so the family name would have come 1st.
2. The amount of chromosomes the domestic horse & 1 of the horses ancestors equus caballus are the opposite way round than stated above. Humans were trying to breed 2 different species of horse & got the extra 2 chromosomes during the breeding process as they were bred into them. It's a simple answer but it'll do.

I know I owe people a few answers but I've got things to say & do too so please be patient & I'll answer you when I can.

 

[Horsa]

I don't remember the difference between Darwin and Lamarck (probably no one ever explained it to me), can you explain it in simple terms here for my benefit?

I haven't read about Lamarck since I was 12 or used any information about Darwin since I left school 20 years ago but from what I remember they had totally contradictory views. Lamarck believed that all animals came from pre-existing parents & that they transmitted all their characteristics off those parents whereas Darwin believed that environment had something to do with it & animals evolved according to their needs to be able to survive harsh environments & fight off predators. Darwin also thought that traits that made animals vulnerable died out.

 

[Horsa]

My time to ask a question, kind of directed to @Chris Koziarz since he manifested his interest in climate change, but obviously everyone is invited to contribute. There is, of course, a lot of political implications in this discussion (which just blur the discussion itself) so I hope we can stick to the point here.

Let me play the devil's advocate and raise the usual counter-argument: accurate data is still very limited to reach a conclusion (at least direct data). This has some truth in it, we are indeed talking about processes that have a time-scale which is quite larger than the data horizon of reliable data we have. I can guess the nature of a few answers to this argument, but I am interested in reading them in full.

Also, I would guess (it is really a guess given my ignorance, not just an euphemism) that "climate change" is one thing, while "global warming" is another (which is one counter-argument against what is above).

By the way, I haven't asked the question yet: how close we are, or can we be, to consensus about climate change?

Actually, the term global warming was used until we had a few very cold winters which made it look as if we were going to go through an ice-age then scientists just changed the name to climate change because the same things caused it. It just had a different effect.

You always get obstinate people & everyone has their own opinion & right to 1 even when you prove them wrong some people will argue "black is white" so I don't think we'll ever reach that point.

 

[Horsa]

Sorry if it sounded rude, I just wanted to jokingly stress that you really speak with authority about the field (nuclear physics). It is not my exact field of expertise, but in all my years at the university I was always inside a nuclear physics group (although studying related fields), so the basics and the standard parlance I know. I have seen nuclear physicists from all over the world and I can tell you that you not only apprehended 100% that you got in your uni courses (which usually is a lot, we just need to check back in our old books to realize how much is there), but you probably added a lot to it independently. It is not the information itself, it is what certain questions are triggering in your answers.

By the way, you have raised the fusion subject, and the main reason I haven't replied was that I thought "there is hardly anything I can say here that this guy does not know already". But there are other posters/readers who could find it interesting, so maybe we could in fact open a thread about it.

I think it's a good idea. I'd find it fascinating & would love to hear what you both have to say. I might have more questions though. (This might put you off as I must be doing your head in asking questions now.)

 

[Chris Koziarz]

Sorry if it sounded rude, I just wanted to jokingly stress that you really speak with authority about the field (nuclear physics). It is not my exact field of expertise, but in all my years at the university I was always inside a nuclear physics group (although studying related fields), so the basics and the standard parlance I know. I have seen nuclear physicists from all over the world and I can tell you that you not only apprehended 100% that you got in your uni courses (which usually is a lot, we just need to check back in our old books to realize how much is there), but you probably added a lot to it independently. It is not the information itself, it is what certain questions are triggering in your answers.

By the way, you have raised the fusion subject, and the main reason I haven't replied was that I thought "there is hardly anything I can say here that this guy does not know already". But there are other posters/readers who could find it interesting, so maybe we could in fact open a thread about it.

I understand your joke, no worries. And thanks for your appreciation. I will open new thread. If the new thread brings opinions of people who know more than we do, it'll be really worth!

 

[Chris Koziarz]

My time to ask a question, kind of directed to @Chris Koziarz since he manifested his interest in climate change, but obviously everyone is invited to contribute. There is, of course, a lot of political implications in this discussion (which just blur the discussion itself) so I hope we can stick to the point here.

[1] Let me play the devil's advocate and raise the usual counter-argument: accurate data is still very limited to reach a conclusion (at least direct data). This has some truth in it, we are indeed talking about processes that have a time-scale which is quite larger than the data horizon of reliable data we have. I can guess the nature of a few answers to this argument, but I am interested in reading them in full.

[2] Also, I would guess (it is really a guess given my ignorance, not just an euphemism) that "climate change" is one thing, while "global warming" is another (which is one counter-argument against what is above).

[3] By the way, I haven't asked the question yet: how close we are, or can we be, to consensus about climate change?

Briefly for now, my top of the head answers to your questions, as I numbered them. Exhausting answers (with supporting references) later as we better understand our positions/opinions.
1. Direct data (if you're talking about climate measures such as temperature, precipitation) maybe limited, but we know many ways to obtain indirect data, so called "proxies", as far back as we can imagine. The well known example of such proxies are provided by antarctic/greenland ice cores. The composition of air bubbles trapped in the ice cores is a direct data about the composition of ancient atmosphere. The 18O isotope enrichment/depletion in the ice tells us the temperature fluctuation (because heavy oxygen is less likely to evaporate from the ocean and precipitate onto antarctic icesheet in cold conditions). The "oldest ice" we've been able to drill is about 800k years, and spans several past ice ages. Very remarkable.
In more recent times (say couple k years), we have tree rings growing dense/soft according to local temperature. We also have temperature gradient in boreholes, so called "geo-thermal gradient", which under unchanged surface conditions, is a constant warming gradient as we descend deeper. But when the gradient shows an unexpected changes at the surface, e.g. as discussed here:
https://www.e-education.psu.edu/earth103/node/752
we have a response of soil to the changed surface temperature. We can calculate the timing of the response when we know heat conductivity of a given soil type, hence we deduce the history of surface temperature.

2. "Global warming" is the average T increase due to a forcing agent, such as current greenhouse gas concentration increase (mainly CO2, also CH4 and others), and is the average global mean. "Climate change" is the change (or more precisely many changes in various locations around the globe) due to changes in global ocean/atmosphere circulation due to global warming. Climate change does not imply warming everywhere. Some region may receive cooling (e.g. Iceland due to decreased Atlantic Meridional Overturning Circulation popularly known as "Gulf Stream" that brings warm tropical waters to N Atlantic), while some (e.g. boreal polar regions) must receive increased warming to makeup for the average T increase. CC also includes changes in precipitations. E.g. more extreme weather events (longer droughts and violent rains) are predicted in a warmer world, because warmer air holds mode water vapour, so warmer air is more "energetic". don't understand your "counter-argument" point. There is nothing argumentative about those definitions.

 

[Chris Koziarz]

My time to ask a question, kind of directed to @Chris Koziarz since he manifested his interest in climate change, but obviously everyone is invited to contribute. There is, of course, a lot of political implications in this discussion (which just blur the discussion itself) so I hope we can stick to the point here.

Let me play the devil's advocate and raise the usual counter-argument: accurate data is still very limited to reach a conclusion (at least direct data). This has some truth in it, we are indeed talking about processes that have a time-scale which is quite larger than the data horizon of reliable data we have. I can guess the nature of a few answers to this argument, but I am interested in reading them in full.

Also, I would guess (it is really a guess given my ignorance, not just an euphemism) that "climate change" is one thing, while "global warming" is another (which is one counter-argument against what is above).

[3] By the way, I haven't asked the question yet: how close we are, or can we be, to consensus about climate change?

Technically, depends how you define the "consensus". But practically, we are settled on the question of if current global warming is caused by human activities (if that's what you mean). 97% of experts who research in this field do agree on Anthropogenic Global Warming. Later comprehensive report by IPCC says that the probability of human cause of GW is "extremely likely" (95% or more) and IPCC is a very conservative and caution organisation. Attribution researchers estimate that the mean value of human contribution to the observed warming be even more than 100%, because the natural processes that we understand, tend to slowly cool the climate (famous impending "ice age"), so human warming overwhelmed said cooling. But if you integrate the probability distributions of A vs N warmings with uncertainty of measurements, you get 95% probability that N is greater than A. BTW, every geologist who also knows about climate science, will tell you that the consensus on e.g. plate tectonic movements theory is lower than the consensus on AGW (i.e. plate tectonic theory is less settled than AGW question).

 

[Chris Koziarz]

Actually, the term global warming was used until we had a few very cold winters which made it look as if we were going to go through an ice-age then scientists just changed the name to climate change because the same things caused it. It just had a different effect.

No, the emphasized is a common misconception. Scientists never "changed the name". The names were always been used as I defined them above. It's a media spin (usually result of false, "sensational" claims by so called "skeptics") that created false image of scientists working in this field. I may find the supporting references later, but I think that "climate change" term was invented before "global warming" in the scholar literature. That is an obvious refutation of the argument that said scientists changed the term "global warming" to "climate change" (for whatever reasons).

 

[Horsa]

No, the emphasized is a common misconception. Scientists never "changed the name". The names were always been used as I defined them above. It's a media spin (usually result of false, "sensational" claims by so called "skeptics") that created false image of scientists working in this field. I may find the supporting references later, but I think that "climate change" term was invented before "global warming" in the scholar literature. That is an obvious refutation of the argument that said scientists changed the term "global warming" to "climate change" (for whatever reasons).

I learnt about global warming in High School but didn't hear the term climate change until much later after the very cold winters so that's where I got the above idea from as well as the media like you stated. Thank you very much for putting me right.

 

[Horsa]

I've got a question which may be classed as an archaeology question too, I guess.

Radio-carbon dating is often used in archaeology. Does anyone know how it works, please?

 

[Horsa]

Coincidentally, when @mrzz posed the question about climate change yesterday, I'd just read that "in 2013, Mongolia had been hit by climate change that badly that 90% of the country was likely to be subjected to desertification.".