Ask a physicist anything. (2)

[Sanguis]

If memory serves, it was that moving at 30mph in an open-air carriage would kill you, and it was a public misconception, not actual science.

But even if it was, science moves on. Our earlier mistakes paved the way for a greater understanding. That's why I have that quote at the top of my signature.

SG1 ftw!

Universe is kinda disappointing, though, it's more like Eastenders than Stargate.

 

[AV1611VET]

It's not inconcievable that an advanced alien race would be able to do things that we cannot.

Pffft --- Noah knew that.

Who, in the 17[sup]th[/sup] century, would know that modern day humans could go to the Moon, communicate instantly across the planet, store food for years at a time, annihilate entire cities with a bomb, etc.

I don't know about the 17[sup]th[/sup] century, but Daniel mentions what would someday be called television and rapid mass transportation.

 

[AV1611VET]

Well, it was the public. Is it the fault of the scientific community that people in Korea (or is it Vietnam...) think that a room fan will suck the oxygen our of your lungs? Public misconceptions are just that: misconceptions by the public. They're unfortunate, but unavoidable.

Scientists aren't part of "the public"?

 

[Chesterton]

If you heat an iron bar in a fire, it will produce photons, glowing hot. Remove it from the fire, and when it cools down it will stop glowing. Does that mean electrons are returning to their previous orbit?

 

[Cabal]

If you heat an iron bar in a fire, it will produce photons, glowing hot. Remove it from the fire, and when it cools down it will stop glowing. Does that mean electrons are returning to their previous orbit?

The glowing is representative of the electrons de-exciting.

The lack of glowing is representative of few electrons being excited at all on those transitions (i.e thermally cool). No excitation means no de-excitation and thus no photons.

 

[Cabal]

Science used to teach that anyone accelerating to 30 m.p.h. or higher would die.

Nope. Or at least, it depends how quickly you were accelerating.

I have a feeling scientists know something they aren't telling us.

About basic Newtonian mechanics? Whatever.

According to empirical observation, unidentified flying objects have accelerated to above-mach speeds from 0 instantaneously, and have even made 90-degree turns at above-mach speeds, with no noticeable damage.

Citation needed.

In my opinion, such maneuvers would have killed the crew; but instead, some scientists evidently think these phenomena are valid enough to build an array of radiotelescopes to attempt communication.

No, they don't. It was precisely the lack of decent evidence for extraterrestrial life that resulted in SETI. The most likely option of detecting intelligent life is in scanning the EM spectrum.

Either way, I propose it stay standing for the sheer value of annoying ignorami like you who love to stand on the sidelines picking holes but contribute nothing of value.

Except for your money, of course. Don't worry, you still get to cash in on the benefits too. You fundamentalists are greedy that way, as you love to point out.

Oh, I see --- blame the public.

Blame where blame is due. It's ok, we realise it's something you're atrocious at.

Scientists aren't part of "the public"?

The public sure as hell aren't scientists.

 

[Chesterton]

Citation needed.

"I done seen it! It was a big, round cigar-shaped object. All lit up and flashin' like a Garth Brooks concert!"

 

[Cabal]

"I done seen it! It was a big, round cigar-shaped object. All lit up and flashin' like a Garth Brooks concert!"

"Well darn tootin, that's good enough fer me! Let's git them thar skeence fellas to build us a ray-dee-o interferrymetric array tellerscope!"

Or not!

 

[AV1611VET]

The glowing is representative of the electrons de-exciting.

Does this occur when an electron gives up its energy and drops down to a lower shell?

 

[Wiccan_Child]

SG1 ftw!

Universe is kinda disappointing, though, it's more like Eastenders than Stargate.

I keep thinking that it's a darker version of Atlantis, but with enough uniqueness to carry it off. Hopefully, they'll introduce a semi-permanent threat to keep the series going .

 

[Wiccan_Child]

If you heat an iron bar in a fire, it will produce photons, glowing hot. Remove it from the fire, and when it cools down it will stop glowing. Does that mean electrons are returning to their previous orbit?

Hot things glow because the heat excites electrons into higher orbits. Electrons are prefer lower orbits, so they fall back down. This releases energy in the form of photons. The more energy the electrons have, the higher orbits they get excited to, and thus higher energy photons are released when they fall back down. That's why hotter (more energetic) things go from invisible microwaves and infra-red rays, to visible red, to yellow, to white, as they get hotter. In other words, something glows red when it's hot enough because there's enough energy for the production of red photons.

Now, electrons are constantly getting excited then falling back down. When an object is cooled to room temperature, the electrons can't get excited as much, so they can't produce visible photons. They still produce low energy photons, mind you. That's how infra-red vision works: our bodies aren't nearly hot enough to emit visible light, but they are hot enough to emit infra-red light.

So it's not that the electrons have fallen back to a lower orbit, because they do that all the time. Rather, it's that the can't get back up to the higher orbits because they don't get enough energy.

Or, to be more precise, not enough electrons can get up there; you'd occasionally get a lucky electron that got up high, but not enough of the time for it to be visible.

 

[Cabal]

Does this occur when an electron gives up its energy and drops down to a lower shell?

Technically, it depends on the shells involved, some transitions are radiationless, but they can wholly be placed in an entirely different set from those that result in photon emission.

 

[Wiccan_Child]

Pffft --- Noah knew that.

That future civilisations would be more advanced? It's hardly a difficult concept to grasp.

I don't know about the 17[sup]th[/sup] century, but Daniel mentions what would someday be called television and rapid mass transportation.

I doubt he actually envisioned television and mass transport. I reckon he said something poetic that bares some vague resemblance to modern technology.

If you throw enough spaghetti at the wall, some of it is going to stick.

Scientists aren't part of "the public"?

In a sense, no. The term 'layman' might be better.

Does this occur when an electron gives up its energy and drops down to a lower shell?

Yes.

 

[catzrfluffy]

1) Does the Moon always have the same orbit around the earth?

2) In those pictures of the planets' orbits around the Sun, they're all on the same level, is that the case or do some of them go around diagonally or even vertically?

3) In a vacuum, is there no G-force?

 

[Wiccan_Child]

1) Does the Moon always have the same orbit around the earth?

No. It's actually receding from the Earth at a few centimetres per year.

2) In those pictures of the planets' orbits around the Sun, they're all on the same level, is that the case or do some of them go around diagonally or even vertically?

They actually are pretty much in a plane. This is because the dust cloud from which they all formed was rotating and thus formed a plane (as anything rotating does; the Earth has it's equator, for instance, which is a plane straight through the middle). All the planets formed in this plane, for complex mathematical reasons that you have to pay £500,000,000 to learn.

Interestingly, not all the objects in the Solar System are like this: some are foreign bodies, attracted to us by the Sun's gravity. Pluto is very likley such an object, as its orbit shows:

It's inclined at an angle of 17°, if you're interested.

3) In a vacuum, is there no G-force?

No, but not because there's no gravity. Because both you and your spaceship are accelerating together at the same rates, you don't notice any movement, so it's as if there's no gravity, and that you're weightless.

Though, that said, gravity up there is rather weak, so it's not that big of an approximation.

 

[canehdianhotstuff]

Yes, the electrons excite under a normal distribution. Some get higher, some get lower levels, but the majority fall under the energy level of whatever colour is being emitted.

 

[Cabal]

1) Does the Moon always have the same orbit around the earth?

How do you mean? Same period, same plane?

2) In those pictures of the planets' orbits around the Sun, they're all on the same level, is that the case or do some of them go around diagonally or even vertically?

Well, depends on your definition of planet.

(Scuse me for a second:

AV, zip it.)

Thanks.

Planets that coalesced from the same planar dust disc will all orbit the sun of that system in the same plane.

For the purposes of this discussion, treating Pluto as one of the classic set of nine planets, as it were, it did not orbit in this plane, instead it orbited at an angle, often coming nearly as close as Neptune does. 1979-1999 was a big time for observations of Pluto as it was at this close point, and will not be this close again until the 23rd century.

3) In a vacuum, is there no G-force?

Difficult to answer - G-force is just any arbitrary acceleration felt, scaled in terms of the Earth's typical gravitational acceleration. Being in a vacuum does not really have anything to do with whether or not you are accelerating. And spacecraft certainly accelerate, so there would be forces on the spacecraft even though it is operating in a vacuum.

 

[AV1611VET]

No, but not because there's no gravity. Because both you and your spaceship are accelerating together at the same rates, you don't notice any movement, so it's as if there's no gravity, and that you're weightless.

Though, that said, gravity up there is rather weak, so it's not that big of an approximation.

Yup.

Technically, there's no such thing as "zero gravity"; since an electron on one side of the universe exerts a pull on an electron on the other side.

They now use the term "microgravity".

Weight occurs when gravity is resisted.

 

[AV1611VET]

(Scuse me for a second:

AV, zip it.)

Thanks.

​

 

[Wiccan_Child]

Yup.

Technically, there's no such thing as "zero gravity"; since an electron on one side of the universe exerts a pull on an electron on the other side.

They now use the term "microgravity".

Weight occurs when gravity is resisted.

Well, not exactly. If the universe only contained two electrons, then smack bang in the middle there would be zero gravity, both in terms of the warping of spacetime and in terms of the force felt by a particle there.