Ask a physicist anything. (3)

[tanzanos]

God! (Because God can do it even when he can't)

Time does exist, in discrete units called Plank time (the shortest possible time between two events, according to current theory). Time is a bit more peculiar at that scale, and we don't quite know why. We know that it should be symmetric (i.e., you can't tell whether a particular interaction is running normally, or if it's been 'reversed' like an old VHS), except... it's not. The weak force (and, as recently discovered, the strong force) violate symmetry.

So, yea. Time exists, but buggered if we know what's going on. In my opinion, classical mechanics deals with things from kilometres to microns, quantum mechanics deals with things from microns to picometres, and anything below that... well, I reckon we should leave that to whatever comes next!

Hmmm. OK! Since gravity affects time and at the quantum level gravity does not play a role then suffice it to say is the arrow of time non linear and reversible or does it fold unto itself. Is this the reason for the chaos inherent at the plank level?

 

[Chesterton]

I was standing in line at the convenience story yesterday, and the guy in front of me had a tatoo of a bar code on the back of his neck. If it's a clean, well-defined tatoo could it be read by a typical scanner that reads off of paper or plastic?

 

[Stephen Kendall]

What do feel about Bloom boxes to produce electrical energy? Will this happen as predicted for a normal family's home for around $2,000 for the unit? It is 50% cheaper than coming off of the electrical grid, but is this cheap enough to change the present system?

 

[tanzanos]

...

 

[tanzanos]

If I leave my water tap open for 3 hours, how much electricity consumption will my metre register

(Hope you reach 20,000 posts)

 

[BrianOnEarth]

I was standing in line at the convenience story yesterday, and the guy in front of me had a tatoo of a bar code on the back of his neck. If it's a clean, well-defined tatoo could it be read by a typical scanner that reads off of paper or plastic?

Yes, if the contrast between skin and bar colours is high enough.

 

[pgp_protector]

I was standing in line at the convenience story yesterday, and the guy in front of me had a tatoo of a bar code on the back of his neck. If it's a clean, well-defined tatoo could it be read by a typical scanner that reads off of paper or plastic?

I should get this tattooed on my hand

 

[Chesterton]

I should get this tattooed on my hand

On the forum page, your reply was reply number 666.

 

[Assyrian]

I should get this tattooed on my hand

Well of course it would says that.

 

[Steffenfield]

Okay, here's another one.

Why did my pizza catch on fire?

I set the oven to only 400 degrees, but, well, yeah, it was still in the delivery cardboard box (I have kitchen issues which I'm currently working on *lol*).

I thought paper could only burn at 451 degrees fahrenheit.

 

[Gracchus]

Okay, here's another one.

Why did my pizza catch on fire?

I set the oven to only 400 degrees, but, well, yeah, it was still in the delivery cardboard box (I have kitchen issues which I'm currently working on *lol*).

I thought paper could only burn at 451 degrees fahrenheit.

There are a couple of possibilities.

The 451 deg F temperature is the ignition point of the paper commonly used in books. The wood or other fiber used in making the cardboard box might have a lower ignition point. If the cardboard was outgassing vapors from the glue, that vapor might have ignited at a lower temperature so that the temperature of the cardboard was raised to its ignition point. The fact that the box probably became impregnated with fat may also have been a factor. If the box was closed the desity of vapor from the fat, the glue or the cardboard might have risen to a point where other reactions were taking place. Or perhaps, just perhaps, your oven's calibration is off.

 

[tanzanos]

There are a couple of possibilities.

The 451 deg F temperature is the ignition point of the paper commonly used in books. The wood or other fiber used in making the cardboard box might have a lower ignition point. If the cardboard was outgassing vapors from the glue, that vapor might have ignited at a lower temperature so that the temperature of the cardboard was raised to its ignition point. The fact that the box probably became impregnated with fat may also have been a factor. If the box was closed the desity of vapor from the fat, the glue or the cardboard might have risen to a point where other reactions were taking place. Or perhaps, just perhaps, your oven's calibration is off.

There is also the accuracy factor of the thermostat! The oven knob may have indicated 450 deg F but in actual fact the oven temperature may have reached 450+ But if we are to understand this issue better then we must use the correct and scientific Metric system and not the Imperial. Also Proper British spelling will further our understanding of the said problem and aid in its solution.

 

[Cabal]

Also Proper British spelling will further our understanding of the said problem and aid in its solution.

Not just that - proper British spelling will actually just result in less fires.

 

[Steffenfield]

Here's another dumb one. But hey, as you guys are getting to know me here, you'll begin to expect them. *lol*

What would it take for outer space to enter our earth's atmosphere or is this not even possible?

If so, what could cause such an event?

Lastly, if it did, what most likely would happen?

It seems like it would just take the path of least resistance and dissipate in the air, but honestly, I don't even have an idea on this.

Thanks.

 

[tanzanos]

Here's another dumb one. But hey, as you guys are getting to know me here, you'll begin to expect them. *lol*

What would it take for outer space to enter our earth's atmosphere or is this not even possible?

If so, what could cause such an event?

Lastly, if it did, what most likely would happen?

It seems like it would just take the path of least resistance and dissipate in the air, but honestly, I don't even have an idea on this.

Thanks.

Although the way you worded your question makes for an impossible condition it can however be asked thus: What would it take for Earth to loose its atmosphere?
Answer:
If the earth's core cooled to the point where a magnetic field cannot be generated (The Earth's magnetic field is generated in the fluid outer core by a self-exciting dynamo process. Electrical currents flowing in the slowly moving molten iron generate the magnetic field (An Overview of the Earth's Magnetic Field)) then the solar wind will eventually push the air molecules away from the Earth and thus render the Earth without an atmosphere. But! if the atmosphere were to cool substantially then the solar wind will not have the energy to excite the air molecules to the point where they will escape the Earth's gravitational pull.

 

[Wiccan_Child]

Here's another dumb one. But hey, as you guys are getting to know me here, you'll begin to expect them. *lol*

What would it take for outer space to enter our earth's atmosphere or is this not even possible?

It's not possible. 'Outer space' is beyond our atmosphere; it's void of pretty much anything, hence why it's called 'space'

It seems like it would just take the path of least resistance and dissipate in the air, but honestly, I don't even have an idea on this.

Well, it's not a 'thing' that can dissipate, it's an absence of stuff. The higher you go, the thinner the atmosphere gets, until it's so thing that it's just a few molecules per cubic metre - i.e., not very much at all.

 

[Cabal]

It's not possible. 'Outer space' is beyond our atmosphere; it's void of pretty much anything, hence why it's called 'space'

I guess you could reduce the reach of the atmosphere by doing (a lot of) work on it? That wouldn't be "outer space" doing the work though, of course.

 

[tanzanos]

I guess you could reduce the reach of the atmosphere by doing (a lot of) work on it? That wouldn't be "outer space" doing the work though, of course.

Actually there is no definitive boundary between space and our atmosphere. The rarification is gradual and some air molecules can be found half way to the moon. Friction on spaceship re-entry starts to show its effects at around 100 km above the surface and space is technically considered to start around 80 km.

Other ways the Earth could loose its atmosphere is extreme heat where the air molecules will reach escape velocity. This can be achieved by the flaring up of the sun during its red giant stage. And of course if the earth lost its magnetic field. Venus is slowly loosing its atmosphere albeit with volcanism it is being replenished. If the earth which has less volcanic activity were to loose its magnetic field then the atmospheric loss would be faster than that of Venus. Mars lost most of its atmosphere (100 times less dense than the Earth's) due to 2 reasons: no magnetic field and less mass thus less gravity.

 

[Cabal]

Actually there is no definitive boundary between space and our atmosphere. The rarification is gradual and some air molecules can be found half way to the moon. Friction on spaceship re-entry starts to show its effects at around 100 km above the surface and space is technically considered to start around 80 km.

Not disagreeing with your post (I <3 the Karman line), but that still doesn't mean one couldn't compress the (bulk of the) atmosphere down given enough energy, but "outer space" itself will typically have less than our atmosphere and will require an external source of energy to pressurise it. So by itself it will not be sufficient to displace our atmosphere.

 

[Delphiki]

Here's another dumb one. But hey, as you guys are getting to know me here, you'll begin to expect them. *lol*

What would it take for outer space to enter our earth's atmosphere or is this not even possible?

If so, what could cause such an event?

Lastly, if it did, what most likely would happen?

It seems like it would just take the path of least resistance and dissipate in the air, but honestly, I don't even have an idea on this.

Thanks.

Well, as explained, space is a vacuum and not actually a substance, so a more proper question would be: "What would it take for the earths atmosphere to receded or drop tot he point that there was no atmosphere covering the surface?"

The first thing that comes to my mind is the movie "The Day After Tomorrow" where a low pressure system was so severe, that the center of it was the vacuum of space. From space, the view would look akin to an enormous hurricane, or funnel in the atmosphere, exposing the ground. Every living thing in the center of such a low pressure system would freeze and die within seconds.

Unlike in the movie, where the helicopter just frosted over and seized up in mid-air, it would actually begin taking a nose-dive as it's altitude ceiling dropped. The helicopter would "suffocate", as would the passengers, if they survived the landing -- long before an "insta-freeze" effect. Take note that space capsules and shuttles aren't overcome by the cold of space.

One interesting side note, for those who aren't familiar with science: There's a limit to cold, but not to heat. Cold is merely the absence of heat, and heat is molecular movement. When molecules stop moving completely, this is 0 degrees Kelvin. There is no colder temperature possible.

Also Kelvin is on the same scale as Celsius. Just subtract 273.15 from Kelvin degrees, and you have Celsius. 0 Kelivin is -273.15 Celsius.