Author Topic: Episode #671  (Read 10041 times)

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Offline Mr. Beagle

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Re: Episode #671
« Reply #30 on: May 27, 2018, 08:14:22 PM »
I have seen the green clouds. I would characterize it as a color artifact or effect from very deep, water laden clouds. In Iowa it means that a hell of a storm is coming.
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Offline CarbShark

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Re: Episode #671
« Reply #31 on: May 28, 2018, 12:18:05 AM »

I have seen green clouds
Deep, dark and water laden
A storm is coming

Now it's a haiku.
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Offline elert

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Re: Episode #671
« Reply #32 on: May 28, 2018, 01:33:28 PM »
I heard, sometime in the distant past, that green skies during severe weather were caused by large pieces of ice (i.e., hailstones). I heard that once and have not bothered to verify it. Just throwing it out to the forum in case it triggers helpful thoughts in someone else.

Also, photons do not have mass and Woody Allen never said they did.

Photons do have mass (equivalent).  Mass is energy and energy is mass.  It’s estimated that the cosmic microwave background photons amount to around 0.1% of the mass of the Universe.

I’ve found references on the Internet to Woody Allen uttering the quotation, and of course everything on the Internet is true, right?

Equivalent mass is not mass any more than equivalent color temperature is temperature. You can't replace the equivalent mass of a photon into any equation that I can think of in relativity. Unless you multiply it by the speed of light squared to get energy back again, which is 2 errors canceling each other out.

Mass is resistance to acceleration and since photons can only travel at one speed in free space, they never accelerate. Since they can't accelerate, they don't have mass.

Offline brilligtove

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Re: Episode #671
« Reply #33 on: May 28, 2018, 02:54:34 PM »
I heard, sometime in the distant past, that green skies during severe weather were caused by large pieces of ice (i.e., hailstones). I heard that once and have not bothered to verify it. Just throwing it out to the forum in case it triggers helpful thoughts in someone else.

Also, photons do not have mass and Woody Allen never said they did.

Photons do have mass (equivalent).  Mass is energy and energy is mass.  It’s estimated that the cosmic microwave background photons amount to around 0.1% of the mass of the Universe.

I’ve found references on the Internet to Woody Allen uttering the quotation, and of course everything on the Internet is true, right?

Equivalent mass is not mass any more than equivalent color temperature is temperature. You can't replace the equivalent mass of a photon into any equation that I can think of in relativity. Unless you multiply it by the speed of light squared to get energy back again, which is 2 errors canceling each other out.

Mass is resistance to acceleration and since photons can only travel at one speed in free space, they never accelerate. Since they can't accelerate, they don't have mass.

If they could not accelerate they could not change direction. Refraction exists, as does gravitational lensing. Photons always travel at the same speed, not the same velocity.
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Offline Friendly Angel

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Re: Episode #671
« Reply #34 on: May 28, 2018, 03:10:28 PM »
If they could not accelerate they could not change direction. Refraction exists, as does gravitational lensing. Photons always travel at the same speed, not the same velocity.

I'm enjoying this discussion.

I'm not sure gravitational lensing requires changing direction the way refraction does though.  Photons just follow the curve of space, which is the photon's definition of a straight line. 
Amend and resubmit.

Offline elert

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Re: Episode #671
« Reply #35 on: June 02, 2018, 12:27:18 PM »
I heard, sometime in the distant past, that green skies during severe weather were caused by large pieces of ice (i.e., hailstones). I heard that once and have not bothered to verify it. Just throwing it out to the forum in case it triggers helpful thoughts in someone else.

Also, photons do not have mass and Woody Allen never said they did.

Photons do have mass (equivalent).  Mass is energy and energy is mass.  It’s estimated that the cosmic microwave background photons amount to around 0.1% of the mass of the Universe.

I’ve found references on the Internet to Woody Allen uttering the quotation, and of course everything on the Internet is true, right?

Equivalent mass is not mass any more than equivalent color temperature is temperature. You can't replace the equivalent mass of a photon into any equation that I can think of in relativity. Unless you multiply it by the speed of light squared to get energy back again, which is 2 errors canceling each other out.

Mass is resistance to acceleration and since photons can only travel at one speed in free space, they never accelerate. Since they can't accelerate, they don't have mass.

If they could not accelerate they could not change direction. Refraction exists, as does gravitational lensing. Photons always travel at the same speed, not the same velocity.

Good point about velocity and speed not being the same thing. My last argument then does not support or refute my contention than photons do not have mass.

Gravitational lensing might not be a good counterexample since gravity is not really a force in general relativity. Photons are just following a geodesic in space-time.

Refraction might not be a good example either but I don't know how quantum mechanics explains that phenomena. Classically when a wave moves from one medium to another and its speed or direction changes it's because of a property of the medium. It's not a change caused by an external force.

Offline daniel1948

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Re: Episode #671
« Reply #36 on: June 02, 2018, 01:43:38 PM »
Photons have no rest mass. They do have mass, though, or they could not import momentum to a solar sail, or to the vains of those things that twirl in the glass globe when sunlight hits them.
Daniel
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Offline RMoore

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Re: Episode #671
« Reply #37 on: June 03, 2018, 11:43:35 AM »
OK when they played the viral audio, I heard Yanni - even though I always heard Laurel before.  I figured it was because I was listening to podcasts at 1.4 speed so I slowed it down and even at 0.3 speed I was still hearing Yanni.

So my conclusion is that it's not just the frequency, or else I would've noticed a difference at the speed.  Those other audio things must be masking the lower frequency out somehow rather than just increasing the frequency of the whole thing.

The low frequencies sound like "Laurel". You would hear "Yanni" if you are missing the low frequencies.

Slowing it down would push those low "Laurel" sounds even lower into the spectrum, so if you are listening on a phone or some other equipment that doesn't reproduce lows very well, you'd be even less likely to hear "Laurel".

Offline RMoore

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Re: Episode #671
« Reply #38 on: June 03, 2018, 11:52:31 AM »
Also, photons do not have mass and Woody Allen never said they did.

Photons do not have rest mass. Try finding a photon at rest, though!

An object in motion has a relativistic mass that is the sum of its rest mass plus its kinetic energy (where the latter is expressed using units of mass, arrived at by dividing the energy by the speed of light squared).

A photon therefore has a relativistic mass that is the sum of its rest mass (0) plus its kinetic energy.

https://en.wikipedia.org/wiki/Mass_in_special_relativity

Offline RMoore

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Re: Episode #671
« Reply #39 on: June 03, 2018, 12:11:01 PM »
[Mass is resistance to acceleration and since photons can only travel at one speed in free space, they never accelerate. Since they can't accelerate, they don't have mass.

If the definition were that simple, it would imply that they have infinite mass, since no amount of force can change their speed.

Also, acceleration can be seen in photons if they change direction, since acceleration is a change of velocity (not speed), and velocity is speed times a directional vector. A gravitational field can change a photon's direction. That's acceleration.

In relativistic physics, it's more useful to think in terms of the kinetic energy. A photon's kinetic energy can change; for example, when falling into a gravitation well, it will acquire more kinetic energy and be blue-shifted.

Offline brilligtove

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Re: Episode #671
« Reply #40 on: June 04, 2018, 12:54:29 PM »
PBS Spacetime has a lot of great videos about topics like this. I'm pretty sure they have one about mass vs rest mass... Yup.



« Last Edit: June 04, 2018, 01:37:21 PM by brilligtove »
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Offline 2397

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Re: Episode #671
« Reply #41 on: June 09, 2018, 05:52:45 PM »
On the topic of climate change, I'm currently the closest I've been to experiencing (significant) consequences from a drought. Seems to be a bit of air in the water from our 60m well, indicating that there's either some kind of breach, or it's getting dry quite far down. Otherwise that only happens when there's low pressure in the pressure tank.

I wonder where Bob plans to move to.

Noting that they've returned to saying they're talking about [product/service] because they love it so much, implying that they're not being paid for advertisements.

Offline daniel1948

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Re: Episode #671
« Reply #42 on: June 09, 2018, 06:38:50 PM »
Noting that they've returned to saying they're talking about [product/service] because they love it so much, implying that they're not being paid for advertisements.

In the early days of radio, the hosts read the advertising copy and personally endorsed the products. At some point it became the general opinion that this was unethical, and they moved to playing commercials produced by the advertisers. Podcasting generally seems to have adopted the early-radio practice of personal endorsement by the hosts. I cannot remember recently hearing an ad on a podcast where the host did not tell us how much he/she loves this product. Sometimes it's quite over-the-top, asserting categorically that the product is the best in the world.

It's kind of disappointing that podcasters who I respect will stoop to making what are clearly exaggerated claims for their advertisers' products. Of all the podcasts I listen to, only Ross & Carrie manage to avoid being obnoxious in their ads. I don't hear the ads on the SGU, but most of the other podcasts are so obnoxious that I have to skip through them, even if I have to quickly drop what I'm doing.
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Offline DevoutCatalyst

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Re: Episode #671
« Reply #43 on: June 09, 2018, 07:27:14 PM »
Noting that they've returned to saying they're talking about [product/service] because they love it so much, implying that they're not being paid for advertisements.

In the early days of radio, the hosts read the advertising copy and personally endorsed the products. At some point it became the general opinion that this was unethical, and they moved to playing commercials produced by the advertisers. Podcasting generally seems to have adopted the early-radio practice of personal endorsement by the hosts. I cannot remember recently hearing an ad on a podcast where the host did not tell us how much he/she loves this product. Sometimes it's quite over-the-top, asserting categorically that the product is the best in the world.

It's kind of disappointing that podcasters who I respect will stoop to making what are clearly exaggerated claims for their advertisers' products. Of all the podcasts I listen to, only Ross & Carrie manage to avoid being obnoxious in their ads. I don't hear the ads on the SGU, but most of the other podcasts are so obnoxious that I have to skip through them, even if I have to quickly drop what I'm doing.
I hate it too. It's as if advertisers found themselves a bunch of naïve suckers and laid down the law about how it's going to be and most podcasters caved. I used to hate Paul Harvey and Charles Osgood for reading ad copy long after many news commentators thought that doing so would shoot their cred and refused. I didn't like Harvey or Osgood for other reasons but that was further reason.

You can get a foam mattress that expands when you open the box from Ikea and others for a lot less than from that company that won't shut up. Was it you Daniel who mentioned that Ira Flatow speaks in the past tense about that mattress, implying that he no longer uses one?  "It's a great mattress but I really couldn't stand it."

If podcasters ran spots the advertisers produced themselves I'd have no objection, especially if there is a paid option for no ads. I currently pay YouTube $10/month to get rid of ads. It's not that I don't know to use an ad blocker, it's that I think it's worth paying Google to turn off their ads. Content producers still get some of my cash, YouTube gets the rest, and I get peace and quiet. Win win win.

Online arthwollipot

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Re: Episode #671
« Reply #44 on: June 09, 2018, 08:53:35 PM »
Noting that they've returned to saying they're talking about [product/service] because they love it so much, implying that they're not being paid for advertisements.

In the early days of radio, the hosts read the advertising copy and personally endorsed the products. At some point it became the general opinion that this was unethical, and they moved to playing commercials produced by the advertisers. Podcasting generally seems to have adopted the early-radio practice of personal endorsement by the hosts. I cannot remember recently hearing an ad on a podcast where the host did not tell us how much he/she loves this product. Sometimes it's quite over-the-top, asserting categorically that the product is the best in the world.

It's kind of disappointing that podcasters who I respect will stoop to making what are clearly exaggerated claims for their advertisers' products. Of all the podcasts I listen to, only Ross & Carrie manage to avoid being obnoxious in their ads. I don't hear the ads on the SGU, but most of the other podcasts are so obnoxious that I have to skip through them, even if I have to quickly drop what I'm doing.
There are podcasts that play prerecorded ads. I heard one recently - I think it was Science Vs - that played a prerecorded advertisement for Australia Post, but it was read out in an American accent. It was extremely weird.
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