Author Topic: Episode #670  (Read 7376 times)

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Offline Steven Novella

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Episode #670
« on: May 12, 2018, 12:21:21 PM »
Interview with Adam Becker
What's the Word: Epiphyte
News Items: Knowledge of Evolution, Hawaii Volcanic Activity, Spider Silk and Steel, Toxic Moon Dust
Who's That Noisy
Science or Fiction
Steven Novella
Host, The Skeptics Guide
snovella@theness.com

Offline BBBlue

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Re: Episode #670 Maggots
« Reply #1 on: May 12, 2018, 01:51:50 PM »
Fly larvae = maggots, beetle larvae = grubs.

Offline Zec

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Re: Episode #670
« Reply #2 on: May 12, 2018, 02:39:05 PM »
Steve's point on evolution "if only dogs would be left after an asteroid they would evolve and differentiate to fill different nices, but they'd still be dogs."
greatly under represents how great the differentiation would be given sufficient time.
think of marsupials for example, they all come from the same ancestor but they differ greatly from being "mouse like" to be "dog like". Of course they are all marsupials, but the are different species compared to each other
or to the commona ancestor.
or dolphins and wales, of course thy are still mammals but they are "fish like" mammals and look nothing like our common which was for sure some sort of mouse like (or perhaps larger) land walking animal
« Last Edit: May 12, 2018, 02:46:57 PM by Zec »

Offline elert

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Re: Episode #670
« Reply #3 on: May 12, 2018, 03:57:10 PM »
Photons don't have mass and I don't think Woody Allen ever said they did.

Online Sawyer

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Re: Episode #670
« Reply #4 on: May 12, 2018, 08:28:55 PM »
Photons don't have mass and I don't think Woody Allen ever said they did.

Then how do they have momentum?   >:D

Offline brilligtove

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Re: Episode #670
« Reply #5 on: May 12, 2018, 09:19:27 PM »
Photons don't have mass and I don't think Woody Allen ever said they did.

Then how do they have momentum?   >:D

Photons do not have rest mass. They do have mass related to the amount to energy the photon is packing. http://www.physlink.com/education/askexperts/ae180.cfm  >:D :love: >:D
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Offline fuzzyMarmot

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Re: Episode #670
« Reply #6 on: May 12, 2018, 10:08:49 PM »
I imagine they are going to get a mountain of e-mail on the photon mass thing. I'm betting they'll do a follow-up on mass, rest mass, etc. next week. And hopefully they'll also clarify whether or not photons are Catholic.

Online bachfiend

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Re: Episode #670
« Reply #7 on: May 12, 2018, 10:39:48 PM »
Steve's point on evolution "if only dogs would be left after an asteroid they would evolve and differentiate to fill different nices, but they'd still be dogs."
greatly under represents how great the differentiation would be given sufficient time.
think of marsupials for example, they all come from the same ancestor but they differ greatly from being "mouse like" to be "dog like". Of course they are all marsupials, but the are different species compared to each other
or to the commona ancestor.
or dolphins and wales, of course thy are still mammals but they are "fish like" mammals and look nothing like our common which was for sure some sort of mouse like (or perhaps larger) land walking animal

The point was that for dogs to fill other ecological niches after an ecological disaster, they’d have to first de-evolve, losing many of the features they currently have (such as being cute, human friendly, squashed faces in many breeds, etc) and then evolve again along other paths acquiring other features such as sharp claws allowing them to climb trees like cats.

Dogs currently are perfectly adapted to their current ecological niche - being adorable parasites on humans.  If humans went extinct, dogs would go extinct too.  No de-evolution would allow them to survive an ecological disaster.
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Offline mabell_yah

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Re: Episode #670
« Reply #8 on: May 12, 2018, 11:06:09 PM »
Re: grub burgers - Sure, mashing up grubs (or maggots) for food is gross. It would be more gross to chainsaw a hunk of flesh off a live cow and through it in a grinder. Ewe!!!

I'm open to the science of an insect diet just as I'm open to injecting vaccines directly into my body or hurtling through the air at hundreds of miles an hour. If science demonstrates that it's safe, nutritious environmentally sound and ethically sound, I'm interested. I might have to read a few positive reviews before I actually put it in my mouth.

Offline Mr. Beagle

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Re: Episode #670
« Reply #9 on: May 12, 2018, 11:12:12 PM »
The Iceland volcano referred to where they stopped the lava flow in the harbor is in Vestmannaeyjar, or the Westman Islands. I have visited this place and it is a great tour, as it combines a bird watching boat trip around the island, visiting very old settlements, as well as the volcano itself, and a museum built right at the edge of the "tephra" debris flow. The museum is built around a house partially enveloped by the tephra.

I have been to Iceland twice on cheap connecting flights out of Minneapolis to Europe. With IcelandAir, you do not pay extra airfare to spend a couple days there, and it is a relatively short night flight from Minneapolis to Reykjavik.  The Vestmannaeyjar tour is a very long day, starting with a very early three-hour bus ride, followed by a ferry, connecting to the main island, then boarding a smaller boat to circle the island.





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Offline wormguy

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Re: Episode #670
« Reply #10 on: May 12, 2018, 11:13:37 PM »
Not to split hairs, but as an invertebrate zoologist I agree, maggots is usually specific to dipterans, grubs, coleoptera. 

Also, it was my understanding that epiphyte normally refers to normal living position, hence epiphyte and epifauna (much more common in the ocean) are superficial in living position.  I would have used parasitic, mutualistic, or just commensal in addition to any epiphyte...though some will consider that if there is not a mutualism (or we don't understand one to exist), then it must be parasitic because it is adding supported mass an usually other stresses to the host.   

Overall, though congrats to the crew for bringing these concepts...regardless of their technical terminology, into broader discussion!

Offline Zec

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Re: Episode #670
« Reply #11 on: May 13, 2018, 11:04:48 AM »
Steve's point on evolution "if only dogs would be left after an asteroid they would evolve and differentiate to fill different nices, but they'd still be dogs."
greatly under represents how great the differentiation would be given sufficient time.
think of marsupials for example, they all come from the same ancestor but they differ greatly from being "mouse like" to be "dog like". Of course they are all marsupials, but the are different species compared to each other
or to the commona ancestor.
or dolphins and wales, of course thy are still mammals but they are "fish like" mammals and look nothing like our common which was for sure some sort of mouse like (or perhaps larger) land walking animal

The point was that for dogs to fill other ecological niches after an ecological disaster, they’d have to first de-evolve, losing many of the features they currently have (such as being cute, human friendly, squashed faces in many breeds, etc) and then evolve again along other paths acquiring other features such as sharp claws allowing them to climb trees like cats.

Dogs currently are perfectly adapted to their current ecological niche - being adorable parasites on humans.  If humans went extinct, dogs would go extinct too.  No de-evolution would allow them to survive an ecological disaster.

Steve is right saying that you cannot de.evolve certain things. For exemple you probably won't go back to lying eggs once you are a mammal, because it's hard to imagine any selective pressure do that.
but dogs would certanly loose most specialised caracteristics they have, once they are not selectively bred by their environment (humans in this case), and they will slowly fill all the available nices.
they will certainly evolve the ability to climb trees, that's easy to imagine.
And eventually we can even expect marine mammals evolving from dogs, or flying animals (like we' got bats from "mice-like" ancestors, not very far off)
. they would definately not be "dogs" animore, there'd be just all sort of species descending from those dogs.

« Last Edit: May 13, 2018, 11:17:24 AM by Zec »

Offline arthwollipot

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Re: Episode #670
« Reply #12 on: May 13, 2018, 05:36:11 PM »
This episode - again - failed to automatically download on the premium feed. It is available on the website, but it is not in the episode list for either the premium or the free feed. The extended interview downloaded okay, but the full episode is just missing.
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Offline brilligtove

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Re: Episode #670
« Reply #13 on: May 13, 2018, 06:00:06 PM »
This episode - again - failed to automatically download on the premium feed. It is available on the website, but it is not in the episode list for either the premium or the free feed. The extended interview downloaded okay, but the full episode is just missing.
Worked fine for me.
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Offline Isranner

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Re: Episode #670
« Reply #14 on: May 13, 2018, 06:12:14 PM »
Bend it Like Newton

Yesterday’s post on testing the assumption that photons are massless raised a few questions for readers.  One of the most common was the idea that the gravitational lensing of light must mean that photons have mass.  After all, if a star or galaxy can deflect light gravitationally, doesn’t that mean the light is gravitationally attracted to it?  If that is the case, doesn’t that mean that light has mass?

Before we delve into the question, we first need to be clear about what we mean by “mass”.  There are actually several different types of mass.  The type that best corresponds to our intuitive understanding is known as inertial mass.  Inertial mass is determined by its resistance to acceleration.  If you push on objects with a force, an object with less inertial mass will accelerate more than one with more inertial mass. 

Another type of mass is known as gravitational mass.  Gravitational mass is what (in Newton’s gravity) causes the gravitational attraction between objects.  When you step on a scale in the morning, you are measuring your gravitational mass.  While technically gravitational mass and inertial mass are not the same thing, we generally treat them as the same thing because of the “principle of equivalence”. 

If you release a ball from the leaning tower of Pisa, the gravitational force on the ball causes it to fall.  The strength of that force depends on the gravitational mass of the ball, but the rate at which it falls depends on the inertial mass of the ball.  But experiments have shown that masses all fall at the same rate in a gravitational field, so that means the gravitational and inertial masses must have the same value.  This equality between gravitational and inertial mass is called the principle of equivalence.  While this was known since at least Galileo’s time, it was Einstein who made the idea central to our understanding of gravity.

The third type of mass is known as relativistic mass.  This stems from Einstein’s theory of special relativity and the equivalence of mass and energy (the famous E equals m c squared).  In that famous equation (which I’ve written about before: http://goo.gl/IlRY9c), E is the energy of a particle, and c is the speed of light.  So if you divide the energy of a particle by the speed of light squared, you get a “mass”, known as the relativistic mass of the particle.

Now if an object is at rest (relative to you) then the relativistic mass has the same value as the inertial mass.  This is sometimes called the “rest mass” of an object.  But in general, relativistic mass is not the same thing as inertial or gravitational mass.  Unfortunately this point isn’t often made clear, so it leads to a great deal of confusion.  When someone says “the mass of an object increases as it approaches the speed of light”, that’s really the relativistic mass.  A fast moving object has not only energy due to its rest/inertial mass, but also a kinetic energy due to its motion.  The relativistic mass due to its total energy is what increases.  Its inertial (and gravitational) mass is unchanged. 

This is the key difference.  Relativistic mass is an apparent mass that depends on how the object is moving relative to you.  Inertial and gravitational mass are inherent properties of an object, and don’t depend on your point of view.

So what does this have to do with whether photons have mass?  Photons have energy, so we can define the relativistic mass of a photon by taking its energy and dividing by the speed of light squared.  The energy of a photon depends upon its wavelength.  Long wavelength (reddish light) photons have less energy than short wavelength (bluish light) photons.  This means photons have different relativistic masses.

Photons don’t have “rest mass” or inertial mass.  Despite popular news articles about “stopping light”, you can’t hold a photon in place.  The “light stopping” experiments are effects of light waves, which is a whole other rabbit hole.  You also can’t accelerate light with a force.  The speed of a photon is constant, so again, no inertial mass.  By the equivalence principle, that also means they have no gravitational mass.

At least that is the accepted answer.  Maybe for photons, their relativistic mass is their inertial/gravitational mass.  How do we know it’s not?  Actually, we have an experiment that proves it, and Arthur Eddington first did it in 1919. 

In 1919 Eddington photographed the positions of stars near the Sun during a total eclipse.  He compared those positions to their positions when the Sun wasn’t there, and found that they had appeared to shift away from the sun.  This is because the Sun gravitationally deflected the starlight slightly.  This bending of light made the stars appear to be in a different direction.  Einstein predicted this light bending due to the curvature of space in his theory of general relativity.  Thus, Eddington proved that Einstein’s theory was correct.

When this story is presented, it’s often said that since photons have no mass Newton’s model predicts light shouldn’t bend.  Einstein’s theory predicts light bending, so this proved Einstein right.  But actually that isn’t entirely the case.  If the relativistic mass of a photon is equated to its inertial and gravitational mass, then Newton’s gravity does predict light bending. 

The catch is that the amount of bending predicted by Newton’s model is half what Einstein’s model predicted.  Eddington actually demonstrated not only that light was gravitationally deflected, but that the amount matched Einstein, and not Newton.  You can see this in the figure below (http://goo.gl/zUDS0Q), which shows three possible outcomes for light pending: Newton is right, and photons are massless (no deflection), Newton is right and photons have mass (some deflection), or Einstein is right, photons are massless and space is curved (more deflection). 

So the gravitational lensing we see from stars and galaxies actually demonstrates that photons aren’t being gravitationally attracted in the Newtonian sense.  Instead, space is warped by mass of stars and galaxies, and the path of light is warped accordingly.
Light really is massless.  You can’t bend it like Newton, but you can bend it like Einstein.
Source: https://plus.google.com/+BrianKoberlein/posts/buCt8UXEfe7

 

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