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Don’t be a jerk. The issue has been explained to you. The precaution of recalling the product is perfectly sensible as there is a risk, to immunocompromised users of the product, if to no one else.

I use it in the formal sense as defined in differential geometry, ie as a structure that allows you to meaningfully define the inner product of tangent vectors at points on the manifold, which in turn gives a meaningful notion of lengths, angles, areas and volumes. Yes. You need to be careful here - the Christoffel symbols and the connection are not the same thing. A connection allows you to relate tangent spaces at different points on the manifold to one another, ie it provides a notion of parallel transport. This is quite independent of any metric, which is to say you can meaningfully have a manifold that is endowed with a connection, but not a metric. The Christoffel symbols then give you the connection coefficients, ie they tell you what effects your connection has in a particular coordinate basis. They do this by describing what happens to basis vectors as you transport them between neighbouring points, which is something you can calculate from the metric and its derivatives. Without a metric you can still do parallel transport, but you can’t tell what happens to lengths and angles when you do it. Long story short - you can have a connection without a metric. See above. Having a different metric changes the Christoffel symbols (they are not tensors!), but not the connection. Ok, but in the context of physics (SR/GR) the term “metric” is most often used in the differential geometry sense. Physically speaking, equivalence then means a diffeomorphism, so that both metrics describe the same spacetime and thus physical situation. But here’s the thing - as explained above, you’re still on the same manifold endowed with the Levi-Civita connection. By changing the metric like this, you’re doing one of two things: 1. You’re describing a different spacetime, ie a different physical situation, since the two metrics aren’t related by any valid diffeomorphism; or 2. You’re describing the same physical situation, but the coordinates you are using no longer have the same physical meaning. I think what you are trying to do is (2). But the thing is that now measurements on your mathematical manifold (ie in the model) no longer correspond to measurements in the real world, so anything you calculate from this - eg the length of a world line - must first be mapped back into suitable physical coordinates to compare them to real-world measurements. Such a mathematical map may or may not exist, depending on the specifics of the setup. This will also change the form of physical laws, so all the various equations etc will be different for each choice of transformation you make. In either case, this creates a lot of additional work and confusion, for no discernible benefit. It would look for differences in the outcomes of experiments if you vary direction of relative motion, as mentioned previously. For example, if a uranium atom decays if you move it in one direction, but doesn’t decay if you move it at a 90° angle to that direction (everything else remains the same), then you have anisotropic space. This has nothing to do with conventions.

Faith is the ONLY thing people have for belief in god(s) and is perhaps the single worst reason to accept something as valid.

Just to elaborate a bit more. When we speak of the invariance (not constancy!) of the speed of light, what this physically means is that the outcome of experiments is always the same in all inertial frames, ie uniform relative motion has no bearing on the outcome of experiments. This has nothing much to do with units or numerical values. Yes, it is always possible to describe the same physical situation in terms of different “geometries”, if you so will. You can eg forego any reference to curvature completely by choosing a different connection on your spacetime - the geometry is now curvature-flat, and instead contains all information about gravity in the form of torsion. But all this is saying is that one can draw different types of maps over the same territory, like having a topographical map vs a road map over the same region. That way you emphasise different information, but the actual experience of physically crossing that terrain is always the same, irrespective of what map you use to navigate. This is not revolutionary or mysterious, and reveals nothing new about the world. It’s “kind of trivial” as the poster in your screenshot correctly said. So I think if you put enough thought into it, it may perhaps be possible to come up with a mathematical description of spacetime in which c is explicitly a function of something. The reason why no one uses such a description is that any measurements of space and time obtained from this description won’t directly correspond to what clocks and rulers physically measure in the real world - you’d have to first map them into real-world measurements, which means additional work and complications without any discernible benefit. Irrespective of what description you use, the outcome of experiments will still be the same in all inertial frames, and this is what we actually observe in the real world.

From the fact that calling it the F-Trump would’ve pleased the wrong audiences. 🥸

There is also a broader issue that you do not want to have uncontrolled bacterial growth in your products. If it is not safeguarded against "safe" bacteria, they may also be vulnerable to harmful ones. And generally speaking, it is better to prevent issue rather than letting it run its course until someone is harmed. That is, unless the penalty is cheaper than safeguarding, which then would be a regulatory issue.

While all newscasting is done by humans and all humans have biases, some sources are particularly good at avoiding spin and focusing instead on providing objective information not on tribal preconception reinforcement and narrative creation (PBS Newshour, as one example), but watching it often feels like eating broccoli so few put forth the effort and prefer the simple “ooh that makes me feel good” stuff. I also advocate for triangulating data across multiple mostly trustworthy sources (such as national defense or global economy focused sources) and forming your own views based on how they overlap and differ with one another, much like you said: On another note… dear leader will now get a new plane from Boeing in the F-47. Trump is an infant with daddy issues.

The plan is to rename it Mar-a-Lego...

I believe that this violates the principle of general relativity. The principle of general relativity requires that clocks and rulers be allowed to behave naturally as clocks and rulers, whereas you are applying corrections to the clocks and rulers based on gravitation in violation of the principle. That the application of the corrections leads to flat spacetime means that the corrections are destroying information about the spacetime being measured. All the information about the measured spacetime is contained in the applied corrections and not at all in the flat spacetime. So, unless you somehow retain the information contained within the corrections and use that information in the description of the measured spacetime, the flat spacetime will not be a valid description of the measured spacetime. You appear to be constructing the following: [math]g_{\mu\nu} = \eta_{\mu\nu} + h_{\mu\nu}[/math] where: [math]g_{\mu\nu}[/math] is the measured metric tensor field using uncorrected clocks and rulers [math]\eta_{\mu\nu}[/math] is the flat spacetime metric tensor field [math]h_{\mu\nu}[/math] is the corrections field One difficulty of the above worth noting is that [math]\eta_{\mu\nu}[/math] and hence [math]h_{\mu\nu}[/math] can be mathematically chosen independently from [math]g_{\mu\nu}[/math], whereas given [math]g_{\mu\nu}[/math], there would seem to be a natural choice of [math]\eta_{\mu\nu}[/math] and hence [math]h_{\mu\nu}[/math]. In obtaining the curvature tensor fields, you would substitute the above expression for [math]g_{\mu\nu}[/math] into the expression of the curvature tensor fields in terms of [math]g_{\mu\nu}[/math] to obtain the expression of the curvature tensor fields in terms of [math]\eta_{\mu\nu}[/math] and [math]h_{\mu\nu}[/math].

So basically unattributed account of an interaction that, as far as I can tell is entirely phony (a quick search revealed similar videos but each with another "professor"). This is astonishingly accurate, but in a sad, vacuous way. Regarding keeping a straight face, he is really good at making very detailed promises (like, autonomous driving by end of next year December, maybe November) and keep doing that for years without showing any level of self-consciousness. But maybe that is because he is such a math genius that actual numbers don't mean anything to him anymore. How does the saying go? Fool me once, shame on you, fool me twice, shame on me. Fool me every time, I must be a Musk fan.

In case there was any question, the CENTCOM classification guide says that both the starting time/date for a mission/operation, and schedules, are classified at the “secret” level https://sgp.fas.org/othergov/dod/r380-14.pdf (I-3, numbers 15 and 16) Declassify happens after mission is over

https://energyeducation.ca/encyclopedia/Earth_Temperature_without_GHGs#

Step 1: Define god in a falsifiable way and in a manner which enjoys shared consensus so the test becomes valid. Go ahead. I’ll wait. <finds cozy spot for a centuries long nap> Have you considered perhaps making better arguments in a more logical, structured, articulate and coherent way? Not perfect, but certainly not impossible. Give it a try sometime! If only someone would invent something like a “search engine” or “library” to help illuminate the dark corners of our ignorance. https://www.idioms.online/jump-the-shark/ Have a happy day, Fonz.

using a pond liner for drinking water might have some risk of microplastics but it depends what its made of most pond liners are pvc epdm or hdpepvc can leak chemicals if its old or in the sun to long not good for drinking water epdm usually safe for fish ponds but not really made for drinking water some kinds might leak stuff in the water hdpe the safest one used for water storage sometimes but only if its made for drinking waterif the liner is falling apart cracking or flaking then yeah tiny plastic pieces could get in the water if its still strong and not breaking then the risk is really smallsince you dont know what kind of liner it is its a bit risky if its old pvc i wouldnt use it if its good hdpe or epdm its probably fine especially if you filter the waterif you want to be extra safe you could use big rocks gravel or a food safe plastic sheet instead that way no chemicals get in the water at all

Don’t mind me I have just read too much Bruce Schenier books. I am not claiming the survey is biased, but is the reason to collect it just to see how educated people would vote or is just to see how those people answer to influence them. By the way I am uneducated in nuclear physics. But you posted this in politics. Is the decision for scientific answers or data. That is using scientific facts to aid in a decision or do you wish to see what is the most important facts to a scientist? I’m beginning to hate politics. But would you say that someone with all the data you collected could use it to manipulate the scientific opinion in their favor? Trump could say that it is clean and abundant. We need to build 20. Biden could say the mining is destruct full and nuclear waste is an issue. So we take all the scientific data and use what parts that fit our purposes. I’m not saying the survey is biased. Scientists would probably give you the reasons we should or shouldn’t. I’m just pointing out the fact that often time scientists’ facts are misused.

Guffaw! (Goldberg ~ gold bird)

To recap - It is just over a week since the Pentagon issued an agency-wide email advisory on March 18th warning all staff that Signal was a potentially insecure communication platform, and should not be used, even for communicating *unclassified* information. https://www.npr.org/2025/03/25/nx-s1-5339801/pentagon-email-signal-vulnerability According to this NPR article, their concerns related to known phishing attacks by professional Russian hacking groups embedding malicious QR codes into spoofed webpages or group chat invites which exploit the ‘Link Device’ mechanism (also found in WhatsApp). It is just 5 days since the New York Times reported that Pete Hegseth had arranged for Elon Musk to attend a top-secret Pentagon ‘O-Plan’ briefing about a potential war with China last Friday 20th March. https://www.nytimes.com/2025/03/20/us/politics/musk-pentagon-briefing-china-war-plan.html The furore aroused by the impropriety of inviting a private businessman with extensive financial exposure to pressure from China to such a sensitive meeting then forced the White House into walking back these plans, and denying that Musk’s visit to the Pentagon had been about anything other than discussing ‘efficiencies’. The Roman Emperor Claudius (AD 41- 54) who suffered from a limp, deafness and a stutter only became Emperor because he was the last surviving adult male of the Julio-Claudian family, once the Praetorian guard had slaughtered his predecessor Caligula and his family. Claudius was a scholar and antiquarian who had been tutored by the historian Livy as a child, and was the last known Roman of high status who could read and speak Etruscan - he actually wrote a long-lost complete grammar of Etruscan - something modern scholars would sell their souls for. He turned out to be a competent ruler and adminstrator of the Roman empire until his demise in AD 54, when he was allegedly poisoned by his wife Agrippina the Younger with toxic mushrooms.

You may be overthinking this a bit. I sympathise, but that's what "flooding the zone with shit" is intended to do to people, so that they have no idea what to make of anything and give up trying to follow it all. The Kremlin does this. I think it went like this. Consider: this bunch of goons has the mindset that all the systems and procedures they have inherited are the cumbersome, bureaucratic and needlessly costly products of a bloated civil service. Consequently, seeing themselves as breath-of-fresh-air iconoclasts, I suspect they thought this is all balls, there are perfectly good commercial encrypted messaging services, so why bother with rules that say we have to use this state-developed[boo hiss] secret squirrel system, we'll just use Signal from now on. And so they did........ BOOM!! 😁 I was very much amused by Waltz preposterously suggesting that Goldberg had deliberately got his phone number into Waltz's address book (how?) and saying he would have to "consult Elon" about how to stop this happening again. What cock! The solution is, er.............to use the special secure system that already exists and whose use is, er, in fact mandated by the current regulations they saw fit to ignore. Waltz's performance put me in mind of particularly unconvincing schoolboy with the feeblest of "dog ate my homework" excuses. Mind you, I think Goldberg might want to make sure his tax affairs are in good shape and that he doesn't get so much as a speeding fine for the next few months. These people now control everything and are extremely vindictive, with the object of scaring everyone into not probing what they are up to.

I think the fact that this is being normalized is a huge issue in itself. Rather unfortunately flooding the zone really works in the age of short - SQUIRREL!

No, dude. Being woke is against the law.

They do have tools for this and special computers called high sides, but these DUI hires simply chose not to use them. https://apps.dtic.mil/sti/pdfs/AD1005160.pdf

AHOTUS works for me

I think microplastics wouldn't be my biggest worry. While I would agree that acute toxicity is likely not an issue, common materials such as PVC can leach plasticizers, such as phthalates. The immediate health impact is low, though accumulation over time is a worry here. I think typical water filters are certified to NSF 42 and 53 (and sometimes 401) which don't test for phthalates (I think). There are PVCs sold as fish or food safe, but not sure whether they are actually compliant to any standards.

As far as I'm aware, most of the uses to which we put ponds would preclude the use of plastics that leach significant amounts of toxic materials. (Who wants a fish pond that kills fish?) Of course, it may have become contaminated in storage.

I must have missed that executive order and it's really fucked up, that Trump is so deranged and ridiculous that if you told me he had legit signed an executive order trying to claim Obama is Kenyan, I'd probably believe it. Oh my God has he actually done that? Yeah I need to start thwarting keyword exploits now and may have to pare down my online presence and hide anything anti-TFG I've said. Still waiting for the conditions on my GC to be removed and they are demanding immigrants social media info now to apply for new GCs or to naturalise. I was going to become a citizen of the USA in a few short years from now, but with Trump in the Whitehouse and the USA going to hell, might be better to just keep my British citizenship as an exit clause. Honestly if my daughter wasn't American I'd already be gone. She and my girlfriend are all that keep me here at this point. That said, if things start to get a little to... Reich like, I'd rather be where the resistance to that needs to be, but maybe I'd send my daughter back to the UK at least. Solidaridad immigrante!

Im 17 and doing A level physics and just wanna say this was so cool to find a post from like 17 years ago asking what ive been thinking for the past few weeks. Anyway instantly made an account as soon as i saw people still active here. Thanks everyone for providing insight here, my classmates just seem to accept most matters and memorise everything so im happy to find people actually digging deeper somewhere. just wanted to leave a mark on this thread

There are toxins that can leach from plastic which would not be filtered. And submicron nanoparticles do come off plastic, which at that size may get through filters. Finally, open ponds can also get windborne particulates and also coming down in rain - a recent study in Colorado croplands found microplastic both in fields and also being absorbed into plant tissues. These were not from some ground source where it was flowing into the fields - they were deposited from the air. So I would say that you combining both physical filters and also chemical detoxing is a good idea, but you may want to look into how your filters handle submicron particles.

The recalled products can contain Pseudomonas species bacteria, including Pseudomonas oleovorans, an environmental organism found widely in soil and water. People with weakened immune systems or external medical devices who are exposed to the bacteria face a risk of serious infection... Immunocompromised folk tend not to roll around in the dirt while they have a break in their skin. The danger is presumably them putting on an article of clothing that recently came from the washer and retained live bacteria. Very low probability but, as with many such threats, a weakened immune system can experience as lethal something most of us wouldn't be affected by. Corporations have an interest in avoiding the reputational harm (and punitive damages awarded by courts) that comes from customers suffering death or serious illness from their products. Many recalls are like this, where a recall is conducted in order to forestall a low probability harm.

The point is, if you can't want your spouse to get a 2,then you're too self absorbed to get married. Be single and do what you want all the time.

All news is worth watching. You just need to realize it's not W Cronkite's news anymore. All news these days, is infected by political spin and ideology ( just like society is ), so you need to do some leg-work for yourself in the way of critically thinking about what is presented/fed to you. Think for yourself, don't let others do it for you.

Did you want an argument or a discussion ? 😀 Could not not stretch a filter fabric over the top of the sump, under the water ? As to the sump material. If it is bituminous I would avoid it, although in the past water tanks have been painted / lined internally with bituminous material, which is not in itself poisonous, in the past there is a risk of cancer from the bitumen.

Ingredients list benzo and methyl isothiazolinones. Maybe left out but more likely contaminated water system

What an extraordinary example of lazy false equivalence. The principle of proportionality is well-established in both domestic and international law and was quite clearly adhered to in the case illustrated in your picture.

Today i learned about genetic mutations, specifically that the reason Siamese cats are so darn cute with their darker patches of fur is because the gene effects an enzyme that functions in cooler temperatures. Their fur color is dependent on temperature which I think is so cool!

Whilst not a Greenhouse Gas and displacing fossil fuel use with renewable Hydrogen will reduce global warming raising atmospheric Hydrogen concentrations slows the decay of methane, which undoes some of the gains. One thing to breed or genetically modify termites (or - seems more likely to me - their accompanying micro biota) to produce more Hydrogen, another thing to harvest and use the H2 cost effectively. Low cost enough that it's use will displace fossil fuel use is a major step that other ways of making Hydrogen have not done successfully; much of that due to the storage and transport difficulties. Adding in the requirements for the termite farms to be inside airtight facilities, for a means of extracting H2 from the air, for a supply of biomass to feed them - all the while maintaining an ideal (termite healthy) air mix and temperatures - makes it extraordinarily challenging. How do the costs compare to dedicated solar, wind, storage powered electrolysis? Meanwhile battery EV's are beating Hydrogen EV's by thousands to one, in part because there are electricity grids EV's are able to take advantage of. With Hydrogen the infrastructure for widespread use does not exist and has to be built from zero. I am cynical enough to think most of the leaders of industries that insist that Hydrogen will be best don't actually believe that themselves. Their Hydrogen efforts so far seem to work better as evidence that low emissions is too hard and expensive than as viable decarbonising.

You don't seem to understand the question...

There's a guy near me that has a drive going over grass and it's great. If you put tarmac down, that's got to be worse. To reinstate that area, all you have to do is pull it up. I think the overall environmental consequence is a fair bit less than the limited leaching it's going to do.

Sounds like a great solution to me. You are finding a use for recycled materials which only makes the demand for recycling greater. I suspect using recycled milk jugs will be much better for the environment than all the fuel that would go into quarrying and transporting stone. And if you no longer want to use it you should be able to recycle the product once again.

I'm dying to get some respect here!

Yes I did. I also took the trouble to research my post and provide some factual sources and date checking, which is a lot more than you did. Do you really believe that the US government was not entitled to carry out a surgical strike to kill Osama Bin Laden in the wake of the largest terrorist assault in history - one which killed more Americans than Pearl Harbour did ? - And if not why not ? Where is your argument ? Why did you try to pass off a photo from 2011 as if were relevant to an issue in 2025 ? I don’t like deceit and innuendo. Say what you mean, and mean what you say.

Hello and welcome. We have another member with similar interests so look at their thread.

Tired of shelling out money for nutty roadside attractions. And Marzipan ain't no place to take a kid. Though I am not without almond joy.

I liked it better when it was in a language I could not read.

He made electric cars sexy and showed that Gerry Anderson had the right idea about rockets. Both fantastic achievements. But then he went mad after his son changed gender and disowned him, started to live in a far-right bubble, raving about the "woke mind virus" and has morphed into a megalomanic Nazi.

Yes welcome, here is some starter information that may be useful. Originally Chemistry was divided into two categories Organic Chemistry and Inorganic Chemistry. The word organic meant that the 'chemicals' ( correct word substances ) derived from living things. Everything else was not organic or inorganic. We now know that this distinction is not accurate but these two categories still remain although organic chemistry has been revised to the chemistry of carbon and its compounds. So basically Chemistry is about all the varous types of substances and the interactions between both themselves and non material things such as light and magnetic fields. Since those early days important sub classifications have been made such as Analytical Chemistry the Science of determining exactly which substances there are in a smaple and how much of each. Physical Chemistry The Science of the physical properties of substances such as density, colour, melting point, boiling point, refractive index, solubility etc Structural Chemistry The study of the internal structure of each and every substance Reachion Chemistry the study of rates and mechanisms if chemical reactions. All of these apply to both Organic and Inorganic Chemistry. Yet more subcategories apply to more specific areas such as biochemistry, mineralogy, crystal chemistry, rheology, molecular chemistry etc.

Very often people come to these fora with a belief that our current theories of physics, such as the Standard Model or relativity, are flawed and present some alternative of their own. On the whole, this is a fine attitude to take - we should always be skeptical, and it is good if people can think a little 'out of the box' and generate ideas which more standard thinkers may not have come up with. I have always thought that genius was not an ability to think 'better' than everyone else - it is an ability to think differently from everyone else. However, when coming up with a new theory it is important that it should be better than the old one. Therefore the first step of coming up with a new theory is a sufficient understanding of the old one. You have to make sure that your new theory does everything at least as well as the old theory, otherwise the old theory remains more attractive. This is very difficult mainly because our current theories are so spectacularly good in their predictions. Let me give an example: the magnetic moment of the electron. If we look at the energy (Hamiltonian) of an electron in an electromagnetic field, we find that there is a contribution from the interaction of the electron's angular momentum and the magnetic field. For an orbital angular momentum [math]L[/math], this is [math]\vec{\mu}_L \cdot \vec{B}[/math] with a magnetic moment [math]\vec{\mu}_L = - \frac{e \hbar}{2mc} \vec{L}[/math] (The charge of an electron is [math]-e[/math] and its mass is [math]m[/math].) However, if the particle has 'spin' (intrinsic angular momentum) [math]\vec{s}[/math], we also have a contribution to the magnetic moment of [math]\vec{\mu}_s = - g \frac{e \hbar}{2mc} \vec{s}[/math] [math]g[/math] is known as the gyromagnetic ratio, and its value depends on the theory. Since this can be measured in experiment very accurately, it is a good test of a theory to check if it predicts the correct gyromagnetic ratio. For example, simple QM (the Dirac equation in an em field) predicts a gyromagnetic ratio [math]g=2[/math]. Experiments shows that [math]g[/math] is very close to 2, so this is good news, but since experiment shows that it is not quite 2, the Dirac equation cannot be the whole answer. Quantum Field Theory, in the form of the Standard Model, predicts a deviation from 2. It is usual to write down the prediction for this deviation from 2 rather than the gyromagnetic ratio itself. For the SM this is: [math]\frac{g_{\rm th}-2}{2} = 1159652140(28) \times 10^{-12}[/math] The experimantal result is: [math]\frac{g_{\rm exp}-2}{2} = 1159652186.9(4.1) \times 10^{-12}[/math] (A note on errors: the numbers in brackets denote the error on the prediction/measurement at the same precision to which the value is specified. For example [math]1159652140(28)[/math] means [math]1159652140 \pm 28[/math] and [math]1159652186.9(4.1)[/math] means [math]1159652186.9 \pm 4.1[/math].) You can see that the theory predicts the correct experimental value to incredible precision (although the experimental error is still better than the theory one). If you want to persuade scientists that the Standard Model is wrong, then you have to explain why this is a coincidence or show that your new theory predicts [math]g-2[/math] to at least this accuracy.