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Agree with @studiot that a piece of information seems to be missing from the problem, in the way you describe it. You don't say over what period of time the deceleration occurs. Without that, you can't know if the deceleration was gradual, due to a small force applied for a long period of time, or sudden, due to a large force applied over a short period.

Yes Yes How ? I think you need to know the time it takes for this to happen or the distance over which it travels during this time.

I hate to corral people into these categories. You miss so much detail of the human landscape. @swansont with license to kill. I can see how that image has been burnt in your memory.

That's nothing. The iron in your blood carrying oxygen to your brain, so you can type, was born before the Sun was born.

There are a lot of anti-vaxxers and nutjobs about at the moment, as you may be aware, that like to cast doubt on the safety and efficacy of vaccination. It looks as though some of the people here have got burnt by this in the past and may have thought you could be one of them, rather than just someone who is not well informed. Risks from the vaccines are small compared to the risks from the disease, even for younger people. Aside from the risk of death or emergency hospitalisation if you are fat, there's a lot of long Covid about. I have a nephew who is very fit (got a half blue at Oxford, rowing for the Lightweights), whose sense of taste has been permanently altered by the virus. I lost my sense of taste and smell totally for a fortnight, which became a bit frightening, though luckily it has come back. The risk of blot clots with the Oxford/AstraZeneca one seems to be about one in half a million: about a fiftieth of the annual risk of blood clots run by a woman on the pill. Nevertheless for those under 40, it is recommended to get one of the other vaccines if possible, for preference, just to avoid even this small risk. As others have pointed out, by getting vaccinated you also help reduce the incidence of Covid in the population as a whole, which reduces the chance of more, nastier, mutations coming along and setting us all back to square one. So yes, get vaccinated. I had my second shot last week (AstraZeneca).

No. When I hired someone for a technical job I didn't care if they were a classic nerd or if they looked like leading man actor, what I cared about is did they seem like they would do the best job.

That's not all that Horton hears when you have chilies, cheese, and beers. You butt was never meant for spam, Mexican, green eggs, and ham.

I think we should leave urinary infections out of this. 😆

I am sorry for not mentioning it before it decelerate in the period of 4 seconds to 4ms-2

In my view, "adversary drones" spying on the US is the least likely scenario. These type of events/craft have been reported since the mid 1940s. Further, with the competitive advantage that the US maintains in terms of military innovation and hardware, I seriously doubt that any adversary would possess technology that we don't know about, or can't respond to. Which leaves two other possibilities: it's our hardware being tested, or it's some other phenomena.

I don't think I can address all the arguments from multiple people in one session and some probably deserve their own thread - and I won't keep at this endlessly - but fwiw - We have a growing capacity to assess the scale of the challenges we face before we face them, to know the theoretical and practical limits we can expect to come up against, to model them. I expect we will get a top to bottom theoretical understanding of the physics of our universe and thus of limits of material properties and processes - and I don't expect it to include magical outcomes. That will allow us to better recognise what is physically possible and what is not. We can also get better at assessing benefits and cost and what is achievable and what is not. We are already good at that and Mars colonies don't stack up. Previous rounds of natural philosophers and scientists getting it wrong doesn't preclude final iterations getting it right; science is already circling in on those final truths. I don't accept the possibilities for ever better technological capabilities are open ended. And some will be hypothetically possible and demonstrable but in practice impossible to exploit due to absence of commercial viability. Like possible Mars colonies. I no doubt don't have the right attitude - I think the commercial viability is absolutely essential to shift from being a taxpayer funded loss making activity to profitable for growth and any inevitability to kick in. Requiring commercial viability is the right attitude. 1, We (US or China, not my nation) probably will send crewed missions to the moon, for national pride. There are credible plans and commitments from the US to do so and abandoning them will look weak. 2, I see no compelling reason to do so - national pride and one-upping China isn't a compelling reason. 3, I doubt there will ever be a colony on the moon - nothing there of value, no commercial base, no way to pay it's way. 4, I see no compelling reason to do so. 5, I think it is unlikely, but possible we will send crewed missions to Mars. For national pride. Or perhaps billionaire's pride. 6, I see no compelling reason to do so. 7, I strongly doubt there will ever be a colony on Mars - because there is nothing there of value, no commercial basis and no way to pay it's way. Without a sound economic basis it fails. 8, I see no compelling reason to do so. 9a, I think it is possible we will establish self supporting civilisations in space but as an emergent outcome from enduring commercial success at asteroid mining for Earth markets - more likely if doing so actually turns out requiring in-space crews and the whole enterprise is not automated and operated remotely. As a goal in and of itself, no. 9b, if 9a then just possibly habitats that thrive entirely on asteroid/cometary resources - if abundance of reliable fusion energy that is readily and reliably copied is achieved, ie energy apart from solar - then they might survive in the Kuiper and Oort. I don't think humans will ever explore other solar systems, even with probes - not unless successive generations build out new habitations ever further out and keep doing so reliably for a few hundred thousand years. 10, I don't believe generation ships will ever be viable. I don't expect exotic reactionless or FTL ships will ever be possible - and if our current Earth civilisation doesn't implode I think we will achieve a complete understanding of the fundamental physics of our universe in this century and will achieve the ability to know for sure. Mining bulk physical commodities for the Earth market - accessing the abundance of iron and nickel and the more valuable elements mixed in with them - has a compelling basis. Success will probably depend on NOT involving astronauts working in space. Meteor defense looks like a good motivation for taxpayer funded space capability. Colonising, as goal in and of itself? No, I don't think it is compelling. If somehow it can be done easily, where it presents economic opportunity, sure, but it looks anything but easy or presenting commercial opportunity. I don't think is possible to compartmentalise any company's finances like that - too opaque and too much overlap. Direct funding for Starship? Offhand I only recall "just" $80M to assist testing rocket engines that appears directly related. The $2.9M moon lander funding has apparently been suspended. I don't have a special issue with companies bidding for government contracts - which by their nature will include profitability for the contractor - but with misrepresenting it as a private enterprise industry and private industry ambition that stands on it's own feet. SpaceX PR seriously understates the difficulties of grand goals like Mars colonies and hypes unrealistic outcomes. I don't believe they will be capable of doing Mars landings as purely private enterprise ventures, let alone colonies. If they do get to Mars "independently" it will be because of enduring profitability in servicing government contracts - and will probably be a poor business decision. I don't believe space tourism can prop it up and make it commercially viable - something of tangible value has to flow back to Earth. I don't believe it is the role of governments to prop such speculative ventures - but concede that others disagree. I am not stopping anyone but SpaceX is popularising Mars missions with unrealistic hype and do engage in lobbying for government support for funding them.

If your nurse looked like Danny DeVito, there may be a pattern here.

AKA "overcoming the curse of knowledge." I like to think about it in terms of tying the knot, and untying the knot.

The self righteous attitude you seemed to have adopted focused entirely on the risk to you and completely ignored the benefit to the community at large that was not something I found attractive. My post placed the option you seemed to be leaning to wards in stark terms in an effort to make clear to you, what you seemed to be finding obscure in the hope you would see your error. The second part of my post suggested what action I thought you should take. It was the one I was 95% certain you would take once oyu had refelcted. If the structure of my post was not clear I'll try harder next time, however, I won't apologise for using strong wording to get your attention. You seemed to need it. I'm not in a position to say if the neg rep you seemingly gave me was warranted. I'm sure the one to @MigL was not, so I've cancelled that out with a Like. Neg rep this post if it makes you feel better.

Have you no family ? Have you no social life ? Is there no-one you wish to protect from getting infected by you ? If so, you have bigger problems than Covid-19 or the vaccines. One thing I have never understood ... They publish the numbers of people ( out of millions ) who get blood clots from the vectorRNA vaccines, Astra-Zeneca and Johnson and Johnson, which have now gotten a bad name as 'second best',but no one has ever given numbers of how many people get blood clots from Covid-19. I would bet good money it is orders of magnitude higher.

@Alfred001If I may express what is implicit in the foregoing responses in a much more vigorous form: go ahead. Don't take the vaccine. Let people know you have not taken the vaccine. Wear a badge clearly stating you have not taken the vaccine. This will allow the rest of us to identify you as ignorant and anti-social. We can then respond accordingly. Alternatively, take the vaccine, thereby improving your chances of avoiding problems, showing your grasp of reality and making an important contribution to community welfare.

I talked to contactees who visited UFOs, but unfortunately they didn't say such exact data. I mean calculations and formulas. They were told the principle of obtaining energy in outer space.