For starters it posits that there was intelligence behind the design of our existance. This can disproven by finding factual evidence to support any one of another different theories.
It's even easier to disprove than that, one merely needs to find evidence supporting "design" features that are stupid, not intelligent. One certainly doesn't have to look far for that, life's full of them. Evolution does a hack job, and it shows.
Agreed. But by the same token, no believer in evolution should be afraid of what creationists or ID proponents have to say either. If it is false they should refute it.
Life's too short to waste it refuting, over and over again, every stupid idea that comes along. I certainly don't "fear" what creationists, moon hoaxers, flat-earthers or anthropogenic global warming believers have to say. I do fear having to waste time, energy and resources dealing with false issues that idiots like that raise (or real issues that they fail to address). Time and money are finite resources, let's not waste them on stupidity.
"Any sufficiently advanced technology is indistinguishable from magic."
Which is NOT to say that any arbitrary magic is indistinguishable from advanced technology. Things that violate well-understood laws of physics without exploiting little-understood loopholes are "magic" that can't be imitated by technology however advanced.
Well, NASA can go fork themselves as far as that goes, but I'll allow as how being a passenger is a little different from being crew. We don't call the folks in the back of commercial airplanes "aeronauts", do we? (Okay, we don't call the pilots that either these days.)
Comes to that, though, they shouldn't call their payload specialists astronauts either. (Personally I don't really think the term should be applied to anyone who isn't exploring space (or testing new space vehicles) -- which means it shouldn't have been applied to Shuttle crews since the early 1980s.)
Given that the Progress resupply ships are essentially unmanned Soyuz capsules, I think you have to count a lot more than merely the 99 manned flights. The launch system is essentially the same in either case, even if there are detail differences in the orbital vehicles. (I can't readily find total number of Progress launches, but it was 43 - all successful - to Salyuts 6 and 7; plus many since then to Mir and 30 to ISS.)
I *do* care if my city is going to be under 20 feed of water a hundred years from now.
Do you live in Venice? Or somewhere else where the land is subsiding about 2-1/2 inches per year? (That's the rate of sea level rise needed for a 20 foot increase in a mere century.)
In fact, the vaunted IPCC figures on sea level rise (on a couple of millimeters a year) were baselined on a guage located in an area known to be subsiding. When satellite altimetry data didn't match those numbers, they applied a "correction factor" to the satellite data so that it would match up.
The Windows 7 version they're frantically working on to replace Vista will be released as Windows Conquistador. It'll run tight. (As in, like somebody whose blood alcohol level is way over the legal limit.)
He could be lying about it, for example to cover up for someone else, who told him afterwards where the body was hidden. I'm not saying it's likely, but certainly it is possible.
Which would at very least make him guilty as an accomplice to murder after the fact, and of obstructing justice and conspiracy to obstruct justice. Oh, and perjury.
So it's a near mathematical certainty he's guilty of something.
Linemen also spend more time in the sun, are more likely to be exposed to PCB residues from transformers, and are exposed to chemicals like arsenic and creosote used as preservatives in wooden poles.
Pogo will always cause a lowered average chamber pressure indication. Pogo, ultimately, is a result of fluctuations in chamber pressure (in turn due to other things and feedback loops), and the net of these fluctuations is a drop. Frequency doesn't really matter.
Oscillations resulting in a higher average combustion pressure would mean destructively high pressure spikes, which the engine is designed to not allow (and tested through such means as detonating a bomb in the combustion chamber while the engine is firing).
If you don't understand the difference, and don't understand why a chamber pressure sensor will detect pogo where a fuel pressure sensor might not, then I suggest you educate yourself. I won't hold my breath.
Except that liquid fueled engines weigh more than solid fueld engines...
Funniest, most wrong thing I've read on Slashdot today.
Hints: look up "specific impulse" and "combustion chamber wall thickness", among others. Hell, look at any kid's introductory book on rockets; it will explain in words short enough for you to understand why solids are (for a given delta-vee) so much heavier than liquids.
Apollo had a pogo suppression system installed after A13 which worked just fine. Pogo is expected on new liquid designs, part of the engineering process is to determine the sources and fix them. Once it's fixed, it's fixed.
By smooth flow of fuel I meant a continuous, predictable flow of combustibles to the combustion chamber, as compared to a solid, where the whole thing is a combustion chamber and all the fuel is already in there, so it just burns -- at a rate dependent on surface area, fuel consistency, and chamber pressure. If there's a crack in the grain, it detonates. However, solids don't pogo.
Combustion instability is just that -- anything that prevents smooth combustion of propellants in the combustion chamber. Resonance can be a prime culprit, if acoustic waves at the resonant frequency of the chamber build up they can alter the reaction rates in different parts of the chamber, with runaway feedback that eventually destroys the engine. The usual design around is to arrange engine surfaces and injectors at angles and in patterns designed to prevent resonance. Inconsistencies in injector flow, due to throttling or unintended effects like pogo or pump cavitation -- can also lead to instability.
As for "the flow of cooling gas in the engine" -- that's highly engine dependent, many engines don't have such a thing. The injectors and injector face are typically cooled by the propellants flowing through them, and chamber walls are often cooled by pumping the fuel though cooling passages before injection. The F-1 engine did dump its turbine exhaust gas into the engine bell about halfway along its length, which did cool the lower end of the bell (relative to the main exhaust stream). Smaller engines with shorter burn times might just use passive cooling, of course.
The Apollo accidents were due to procedural flaws. Yes, the designs could have been better, but the accident root causes were procedural. (Ground test in 16 PSI O2, improper documentation and handling procedures on the A13 lox tank.)
The Shuttle accidents were due to a design error, aggravated by pushing procedures beyond limits put in place because of those flaws (like launching Challenger on the coldest day of the year with ice all over the pad). The design flaw in both was putting the Orbiter on the side of the ET. This leads to severe bending moments on the SRBs at main engine ignition, and vulnerability to ice/foam falling from the ET during launch. (Other design flaws like the segmented SRBs didn't help either.)
Unfortunately - materials that were flame-retardant or flameproof in normal air became extremely volatile in the 100% oxygen atmosphere in the capsule. They changed to a different mixture after that accident.
Close but not quite. The materials were also flame-retardant or resistant at 100% oxygen atmosphere at the pressure specified for flight, about 3 psi. (The same as the partial pressure of O2 in normal air.) This they did not change after the accident.
The accident happened because they wanted to run the pad test at a higher pressure than the outside -- to simulate that aspect of flight conditions -- and so ran up the cabin pressure to 16 PSI -- of pure O2. Things that won't burn in 3 PSI O2 can burn quite vigorously at 16 PSI O2. Worse, NASA had been warned by North American about the dangers in a high pressure O2 environment. This procedure they did change after the accident, along with making a number of design changes on the CM.
(Ironically, one of the design issues on the CM was the inward-opening hatch, which Grissom had insisted on after the explosive bolts on his Mercury hatch underwent an uncommanded detonation after splashdown and he almost drowned. The inward-opening hatch meant the astronauts couldn't open it as pressure rose in the capsule because of the fire. The redesign included an easier to open, outward swinging hatch.) (Many years later, the likely cause of the uncommanded detonation of the explosive bolts is believed to be due to static buildup because of the recovery helicopter's downwash.)
By complete, pure luck, a fuel sensor tripped and shut the engine down literally seconds before the entire rocket was destroyed.
Wrong. It was an engine pressure sensor that tripped, due to pressure fluctuations naturally associated with pogo. Luck had nothing to do with it.
Apollo 13 was also a huge failure of engineering. Remember all that improvisation they had to do to fit the CO2 scrubbers from the one craft into the other? Why were they not interchangeable?
Because of a management decision to have the LM and CM built by separate vendors, and not consult with each other on design details like the shape of LiOH canisters.
the root cause of the famous accident was due to faulty design and faulty engineering procedures. The wires which triggered the explosion were clad in teflon (not exactly the strongest material), and the whole tank had been dropped during an equipment swap for Apollo 10.
None of which would likely have mattered if it hadn't been for the management decision to raise the tank temperature above spec after a test to boil the lox out of the tank to empty it faster. Oh, and the management failure to track that the spec'ed voltage on the part was increased after manufacture. The whole thing was a cluster fsck.
Mind, the Apollo 13 crew made it back. The crews of Challenger and Columbia didn't.
Apollo 13 briefly scared the crap out of everyone involved when the center engine of the second stage nearly ripped the entire rocket to little pieces. It was experiencing pogo oscillation, flexing the massive thrust frame by three inches at 16Hz, experiencing 68 gees.
You're greatly exaggerating the Wikipedia entry, which itself exaggerates the actual facts. (What, Wikipedia not accurate? I'm shocked!)
There was a known pogo issue on the center S-II engine, observed at 18 Hz on Apollo 8, apparently limited by non-linearities in the system. On the next flight they increased tank pressure but that didn't eliminate pogo and measurement showed G's getting too close to design limits. On the next few flights they built in an early shutdown of the center engine, but several bursts of pogo showed up on Apollo 12 (which had its own share of excitement, being struck by lightning just after launch). There was a pogo-suppressor designed to fix the problem, but installing it on Apollo 13 was problematic because the vehicle was already stacked. Early in the second stage flight they observed a couple of rounds of self-limiting 16 Hz pogo as on Apollo 12, but then next round ran away and vibration forces on the center engine built up.
The center engine shutdown was initiated by a pressure sensor - the pogo is related to wild variations in engine pressure (both cause and effect) and the engine pressure sensor sensed low average pressure and shut the engine down before any damage occurred. It was not "a fuel sensor falsely tripped", but a correctly operating pressure sensor that caused the shutdown. The four outboard engines then just burned longer to make up the difference. In no way did the center engine "nearly rip the entire rocket to little pieces".
All later flights had the pogo suppressor installed and had no problems.
Pogo isn't due to an aerodynamic instability, it's due to feedback cycles in the fuel/engine system. Simply put, the more G's the rocket experiences, the faster the fuel wants to flow into the engine, increasing thrust, increasing G's, etc. Now, the fuel system is designed to limit that for obvious reasons. Pogo happens when the control mechanisms don't react quite as fast as the feedback cycle and overcorrect. Another cause of pogo (serious on Saturn V until they figured it out) is hydraulic effects in the fuel plumbing, akin to "water hammer" in house plumbing.
Geminis were something of an intense ride, the Titan II booster was originally designed as an ICBM launcher and they hit something like 8 gees during the ride out. Overall though still somewhat smoother than a 3 gee Shuttle launch with the random vibrations from its solids.
some inefficiencies in other areas (like shock absorbers and weights) might be tolerable provided that such problems are not the result of more fundamental design flaws in the Ares rocket.
Well that's the thing, see. These problems are the result of more fundamental design flaws in the Ares rocket -- specifically, designing the thing with a single solid first stage to start with.
Solids give a notoriously rough ride. Liquid fuel engines are fed a smooth flow of fuel and are fine tuned to keep out any combustion instability or oscillation. Solids are just a big chunk of almost-explosive with a hole drilled down the middle -- once you light it, that's it. Except for ammunition (ICBMs, artillery rockets, etc), traditionally solids have been used in multiples, usually together with a liquid-fueled core. The advantage is that the thrust variations of multiple solids tends to average out -- you still get vibration, but not as bad. But Ares 1 went with a single, huge, solid stage. That's like designing-in a vibration problem.
On top of that, the damn thing is a hammerhead design, wider at the top than at the bottom (look at the picture, it looks like a corn dog). Those are notoriously prone to stability problems of their own. With liquid fueled engines with some throttle range and gimballed for steering, that's a minor issue. With a solid whose idea of throttle control is cutting the right shape hole down the middle so as to expose different amounts of burning surface at different times, and whose gimballing ability is, well, limited at best -- you'd better hope you don't have any unexpected issues with that inherent hammerhead instability -- like wind shear, or oh say unexpected excessive vibration.
The whole thing is a freaking kludge, and adding a ton of active dampening is just yet another kludge. The manned spacecraft division of NASA jumped the shark a long time ago, this is just further proof.
You can't be nice to someone who doesn't exist, nor can you be nice to someone who no longer exists.
Perhaps not, but you can go through the motions. The ex-person may not care (or even know), but you and those around you will. Some of them may think you're an idiot, some of them will appreciate it. If you're trying to win friends and influence people, or even just make time with the grieving widow, which path do you think will be more successful?
None of it has anything to do with belief in the supernatural, but rather with habits of behaviour and the persistence of memory that make people act, sometimes, as if the deceased is still somehow present.
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For starters it posits that there was intelligence behind the design of our existance. This can disproven by finding factual evidence to support any one of another different theories.
It's even easier to disprove than that, one merely needs to find evidence supporting "design" features that are stupid, not intelligent. One certainly doesn't have to look far for that, life's full of them. Evolution does a hack job, and it shows.
Agreed. But by the same token, no believer in evolution should be afraid of what creationists or ID proponents have to say either. If it is false they should refute it.
Life's too short to waste it refuting, over and over again, every stupid idea that comes along. I certainly don't "fear" what creationists, moon hoaxers, flat-earthers or anthropogenic global warming believers have to say. I do fear having to waste time, energy and resources dealing with false issues that idiots like that raise (or real issues that they fail to address). Time and money are finite resources, let's not waste them on stupidity.
"Any sufficiently advanced technology is indistinguishable from magic."
Which is NOT to say that any arbitrary magic is indistinguishable from advanced technology. Things that violate well-understood laws of physics without exploiting little-understood loopholes are "magic" that can't be imitated by technology however advanced.
Well, NASA can go fork themselves as far as that goes, but I'll allow as how being a passenger is a little different from being crew. We don't call the folks in the back of commercial airplanes "aeronauts", do we? (Okay, we don't call the pilots that either these days.)
Comes to that, though, they shouldn't call their payload specialists astronauts either. (Personally I don't really think the term should be applied to anyone who isn't exploring space (or testing new space vehicles) -- which means it shouldn't have been applied to Shuttle crews since the early 1980s.)
Given that the Progress resupply ships are essentially unmanned Soyuz capsules, I think you have to count a lot more than merely the 99 manned flights. The launch system is essentially the same in either case, even if there are detail differences in the orbital vehicles. (I can't readily find total number of Progress launches, but it was 43 - all successful - to Salyuts 6 and 7; plus many since then to Mir and 30 to ISS.)
I *do* care if my city is going to be under 20 feed of water a hundred years from now.
Do you live in Venice? Or somewhere else where the land is subsiding about 2-1/2 inches per year? (That's the rate of sea level rise needed for a 20 foot increase in a mere century.)
In fact, the vaunted IPCC figures on sea level rise (on a couple of millimeters a year) were baselined on a guage located in an area known to be subsiding. When satellite altimetry data didn't match those numbers, they applied a "correction factor" to the satellite data so that it would match up.
The Windows 7 version they're frantically working on to replace Vista will be released as Windows Conquistador. It'll run tight. (As in, like somebody whose blood alcohol level is way over the legal limit.)
I guess that explains why I seem to get more spam than most.
He could be lying about it, for example to cover up for someone else, who told him afterwards where the body was hidden. I'm not saying it's likely, but certainly it is possible.
Which would at very least make him guilty as an accomplice to murder after the fact, and of obstructing justice and conspiracy to obstruct justice. Oh, and perjury.
So it's a near mathematical certainty he's guilty of something.
Why is it that Superman just stands there and lets you shoot at him, but he ducks when you throw the empty gun at him?
He doesn't. Come on, cite an example. Even in the old George Reeves TV series he didn't.
True enough. Just so long as they don't add moveable weights to counter that vibration mode.
Wow, look at the capsule oscillate. That can't be helpful -- or comfortable (even without the sudden stop).
Linemen also spend more time in the sun, are more likely to be exposed to PCB residues from transformers, and are exposed to chemicals like arsenic and creosote used as preservatives in wooden poles.
Pogo will always cause a lowered average chamber pressure indication. Pogo, ultimately, is a result of fluctuations in chamber pressure (in turn due to other things and feedback loops), and the net of these fluctuations is a drop. Frequency doesn't really matter.
Oscillations resulting in a higher average combustion pressure would mean destructively high pressure spikes, which the engine is designed to not allow (and tested through such means as detonating a bomb in the combustion chamber while the engine is firing).
Again, it was NOT a fuel pressure sensor.
It was a chamber pressure sensor.
If you don't understand the difference, and don't understand why a chamber pressure sensor will detect pogo where a fuel pressure sensor might not, then I suggest you educate yourself. I won't hold my breath.
Except that liquid fueled engines weigh more than solid fueld engines...
Funniest, most wrong thing I've read on Slashdot today.
Hints: look up "specific impulse" and "combustion chamber wall thickness", among others. Hell, look at any kid's introductory book on rockets; it will explain in words short enough for you to understand why solids are (for a given delta-vee) so much heavier than liquids.
Apollo had a pogo suppression system installed after A13 which worked just fine. Pogo is expected on new liquid designs, part of the engineering process is to determine the sources and fix them. Once it's fixed, it's fixed.
By smooth flow of fuel I meant a continuous, predictable flow of combustibles to the combustion chamber, as compared to a solid, where the whole thing is a combustion chamber and all the fuel is already in there, so it just burns -- at a rate dependent on surface area, fuel consistency, and chamber pressure. If there's a crack in the grain, it detonates. However, solids don't pogo.
Combustion instability is just that -- anything that prevents smooth combustion of propellants in the combustion chamber. Resonance can be a prime culprit, if acoustic waves at the resonant frequency of the chamber build up they can alter the reaction rates in different parts of the chamber, with runaway feedback that eventually destroys the engine. The usual design around is to arrange engine surfaces and injectors at angles and in patterns designed to prevent resonance. Inconsistencies in injector flow, due to throttling or unintended effects like pogo or pump cavitation -- can also lead to instability.
As for "the flow of cooling gas in the engine" -- that's highly engine dependent, many engines don't have such a thing. The injectors and injector face are typically cooled by the propellants flowing through them, and chamber walls are often cooled by pumping the fuel though cooling passages before injection. The F-1 engine did dump its turbine exhaust gas into the engine bell about halfway along its length, which did cool the lower end of the bell (relative to the main exhaust stream). Smaller engines with shorter burn times might just use passive cooling, of course.
The Apollo accidents were due to procedural flaws. Yes, the designs could have been better, but the accident root causes were procedural. (Ground test in 16 PSI O2, improper documentation and handling procedures on the A13 lox tank.)
The Shuttle accidents were due to a design error, aggravated by pushing procedures beyond limits put in place because of those flaws (like launching Challenger on the coldest day of the year with ice all over the pad). The design flaw in both was putting the Orbiter on the side of the ET. This leads to severe bending moments on the SRBs at main engine ignition, and vulnerability to ice/foam falling from the ET during launch. (Other design flaws like the segmented SRBs didn't help either.)
Unfortunately - materials that were flame-retardant or flameproof in normal air became extremely volatile in the 100% oxygen atmosphere in the capsule. They changed to a different mixture after that accident.
Close but not quite. The materials were also flame-retardant or resistant at 100% oxygen atmosphere at the pressure specified for flight, about 3 psi. (The same as the partial pressure of O2 in normal air.) This they did not change after the accident.
The accident happened because they wanted to run the pad test at a higher pressure than the outside -- to simulate that aspect of flight conditions -- and so ran up the cabin pressure to 16 PSI -- of pure O2. Things that won't burn in 3 PSI O2 can burn quite vigorously at 16 PSI O2. Worse, NASA had been warned by North American about the dangers in a high pressure O2 environment. This procedure they did change after the accident, along with making a number of design changes on the CM.
(Ironically, one of the design issues on the CM was the inward-opening hatch, which Grissom had insisted on after the explosive bolts on his Mercury hatch underwent an uncommanded detonation after splashdown and he almost drowned. The inward-opening hatch meant the astronauts couldn't open it as pressure rose in the capsule because of the fire. The redesign included an easier to open, outward swinging hatch.) (Many years later, the likely cause of the uncommanded detonation of the explosive bolts is believed to be due to static buildup because of the recovery helicopter's downwash.)
By complete, pure luck, a fuel sensor tripped and shut the engine down literally seconds before the entire rocket was destroyed.
Wrong. It was an engine pressure sensor that tripped, due to pressure fluctuations naturally associated with pogo. Luck had nothing to do with it.
Apollo 13 was also a huge failure of engineering. Remember all that improvisation they had to do to fit the CO2 scrubbers from the one craft into the other? Why were they not interchangeable?
Because of a management decision to have the LM and CM built by separate vendors, and not consult with each other on design details like the shape of LiOH canisters.
the root cause of the famous accident was due to faulty design and faulty engineering procedures. The wires which triggered the explosion were clad in teflon (not exactly the strongest material), and the whole tank had been dropped during an equipment swap for Apollo 10.
None of which would likely have mattered if it hadn't been for the management decision to raise the tank temperature above spec after a test to boil the lox out of the tank to empty it faster. Oh, and the management failure to track that the spec'ed voltage on the part was increased after manufacture. The whole thing was a cluster fsck.
Mind, the Apollo 13 crew made it back. The crews of Challenger and Columbia didn't.
Apollo 13 briefly scared the crap out of everyone involved when the center engine of the second stage nearly ripped the entire rocket to little pieces. It was experiencing pogo oscillation, flexing the massive thrust frame by three inches at 16Hz, experiencing 68 gees.
You're greatly exaggerating the Wikipedia entry, which itself exaggerates the actual facts. (What, Wikipedia not accurate? I'm shocked!)
There was a known pogo issue on the center S-II engine, observed at 18 Hz on Apollo 8, apparently limited by non-linearities in the system. On the next flight they increased tank pressure but that didn't eliminate pogo and measurement showed G's getting too close to design limits. On the next few flights they built in an early shutdown of the center engine, but several bursts of pogo showed up on Apollo 12 (which had its own share of excitement, being struck by lightning just after launch).
There was a pogo-suppressor designed to fix the problem, but installing it on Apollo 13 was problematic because the vehicle was already stacked. Early in the second stage flight they observed a couple of rounds of self-limiting 16 Hz pogo as on Apollo 12, but then next round ran away and vibration forces on the center engine built up.
The center engine shutdown was initiated by a pressure sensor - the pogo is related to wild variations in engine pressure (both cause and effect) and the engine pressure sensor sensed low average pressure and shut the engine down before any damage occurred. It was not "a fuel sensor falsely tripped", but a correctly operating pressure sensor that caused the shutdown. The four outboard engines then just burned longer to make up the difference. In no way did the center engine "nearly rip the entire rocket to little pieces".
All later flights had the pogo suppressor installed and had no problems.
Pogo isn't due to an aerodynamic instability, it's due to feedback cycles in the fuel/engine system. Simply put, the more G's the rocket experiences, the faster the fuel wants to flow into the engine, increasing thrust, increasing G's, etc. Now, the fuel system is designed to limit that for obvious reasons. Pogo happens when the control mechanisms don't react quite as fast as the feedback cycle and overcorrect. Another cause of pogo (serious on Saturn V until they figured it out) is hydraulic effects in the fuel plumbing, akin to "water hammer" in house plumbing.
Geminis were something of an intense ride, the Titan II booster was originally designed as an ICBM launcher and they hit something like 8 gees during the ride out. Overall though still somewhat smoother than a 3 gee Shuttle launch with the random vibrations from its solids.
some inefficiencies in other areas (like shock absorbers and weights) might be tolerable provided that such problems are not the result of more fundamental design flaws in the Ares rocket.
Well that's the thing, see. These problems are the result of more fundamental design flaws in the Ares rocket -- specifically, designing the thing with a single solid first stage to start with.
Solids give a notoriously rough ride. Liquid fuel engines are fed a smooth flow of fuel and are fine tuned to keep out any combustion instability or oscillation. Solids are just a big chunk of almost-explosive with a hole drilled down the middle -- once you light it, that's it. Except for ammunition (ICBMs, artillery rockets, etc), traditionally solids have been used in multiples, usually together with a liquid-fueled core. The advantage is that the thrust variations of multiple solids tends to average out -- you still get vibration, but not as bad. But Ares 1 went with a single, huge, solid stage. That's like designing-in a vibration problem.
On top of that, the damn thing is a hammerhead design, wider at the top than at the bottom (look at the picture, it looks like a corn dog). Those are notoriously prone to stability problems of their own. With liquid fueled engines with some throttle range and gimballed for steering, that's a minor issue. With a solid whose idea of throttle control is cutting the right shape hole down the middle so as to expose different amounts of burning surface at different times, and whose gimballing ability is, well, limited at best -- you'd better hope you don't have any unexpected issues with that inherent hammerhead instability -- like wind shear, or oh say unexpected excessive vibration.
The whole thing is a freaking kludge, and adding a ton of active dampening is just yet another kludge. The manned spacecraft division of NASA jumped the shark a long time ago, this is just further proof.
Microsoft announces its new product for distributed computing architectures, "Microsoft Cloud".
You can't be nice to someone who doesn't exist, nor can you be nice to someone who no longer exists.
Perhaps not, but you can go through the motions. The ex-person may not care (or even know), but you and those around you will. Some of them may think you're an idiot, some of them will appreciate it. If you're trying to win friends and influence people, or even just make time with the grieving widow, which path do you think will be more successful?
None of it has anything to do with belief in the supernatural, but rather with habits of behaviour and the persistence of memory that make people act, sometimes, as if the deceased is still somehow present.