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Episode 50 — Gravity


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#21 Luke HENDERSON!

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Posted 02 May 2012 - 12:47 PM

First post is something like this? Seeing these '1 posts' on all of the boards of Earwolf with very negative comments and no back up.

View Posttbain, on 02 May 2012 - 08:28 AM, said:

Love the podcast... but this episode was painful! Christina was a great guest from a comedic perspective, but she got a lot of things just straight up wrong! It was like nails on a chalkboard hearing David and Kyle get excited about understanding
something, when the explanation wasn't even close to correct.


#22 Jookerson

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Posted 02 May 2012 - 02:25 PM

David Silverman seems open to coming on the show.

#23 SUH

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Posted 02 May 2012 - 04:35 PM

Atheism: The lack of belief in a god. (Can be a positive belief there is no god)
Agnosticism: The belief that one cannot have knowledge of whether or not there is a god. The root gnosis means knowledge, therefore agnosis means not knowable.

Agnosticism is compatible with atheism and theism, it is not a "mid point" between the two. Belief is different from knowledge.

#24 Matts

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Posted 02 May 2012 - 05:20 PM

Hi everyone, long time listener of the podcast and only my first post.

I just wanted to pipe in because I'm not sure about a lot of things being "straight up wrong." I'm not a physicist. But there was one thing that caught my ear, and it's not so much about Christina being wrong as it is Aaron being correct. Christina more or less described 'gravitational lensing,' which is the effect that gravity has on light over long distances. But Aaron was also correct. I don't know the percentage, but many, many exoplanets have been discovered based upon observations of the star's "wobble." In fact, the math is so precise that several planets orbiting a single star have been discovered this way.
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#25 tbain

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Posted 02 May 2012 - 05:46 PM

Sorry for not posting more of an explanation after my initial criticism. I understand that is a bit of bad internet etiquette on my part but I was riled up after listening on my way home, and decided today was the day to begin posting. To be honest I planned to try and listen to it again and go through things in in detail, but haven't done so yet.

The first thing that really caused my ears to perk up while listening was Christina's explanation of the four forces. I don't recall the exact wording, but she says something like "the strong nuclear force is what's responsible for holding protons and neutrons together in the nucleus, and the weak nuclear force is responsible for holding together the quarks inside the protons and neutrons". This is just not true. The strong force is responsible for both of those phenomena. The traditional thing to cite, when explaining what the weak force is responsible for, is nuclear beta decay, but this is a rather esoteric topic itself so it doesn't come with much explanatory power.

I also had a hard time listening to her try and explain the incompatibility of quantum mechanics and gravity. Kyle asks something to the affect of "is the lack of gravity what makes quantum mechanics, quantum mechanics?" She fumbles around a bit saying something about quanta, and Plancks constant without ever really explaining what the issue is.

So, the standard model of particle physics (that she references a few times) is really two theories: Quantum Chromodynamics, which is the theory of the strong force, and (the un-cleverly named) Electroweak Theory, which is the theory of electricity ( and magnetism) and the weak force. These two theories are both Quantum Field Theories, or to just call them "Quantum Mechanics" is enough for my point. The formal mathematical description of these theories is complete, however, it's very difficult to carry out any practical calculation, and in practice everything is approximated (although these approximations can be extremely accurate, some of the best predictions in science in fact).

The theory of gravity on the other hand comes from Einsteins theory of General Relativity. It too is a "Field Theory", but not a quantum field theory. It explains gravity by positing that any mass or energy actually curves the space around it, and an object moving under the influence of gravity is actually just following the curvature of space, dictated by the distributed mass and energy. So, in general relativity the objects dictate the curvature of space, while also moving through this curved space, and the actual equations of the theory are like a feedback loop, both generating the curvature, and explaining how to move through the curvature.

Now people have been trying formulate a quantum theory of gravity since quantum mechanics came on the scene, but the problem is that quantum theories are already extremely hard to make calculate, and those calculations are done assuming the space around the particles is flat. Quantum field theories happen "in" space, where as general relativity actually changes the space. So far no one has been successful in combining these theories, and creating a quantum theory of gravity.

Luckily, as Christina does say, gravity is all but negligible except at the largest mass scales (planets, stars, galaxies etc.) and at these large mass scales, the quantum theories are negligible. However, things that are both massive and tiny (understanding the internal structure of a black hole for instance) would require a quantum theory of gravity.

Alright, maybe that was a bit much. And my first post not enough. I'll work on moderation.

#26 RabidMoose

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Posted 02 May 2012 - 10:57 PM

Yeah gravitational forces are pretty cool.

F = Gm1m2 / r2

#27 George Burdell

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Posted 03 May 2012 - 07:38 AM

View PostSUH, on 02 May 2012 - 04:35 PM, said:

Atheism: The lack of belief in a god. (Can be a positive belief there is no god)
Agnosticism: The belief that one cannot have knowledge of whether or not there is a god. The root gnosis means knowledge, therefore agnosis means not knowable.

Agnosticism is compatible with atheism and theism, it is not a "mid point" between the two. Belief is different from knowledge.



PLEASE, PLEASE everyone read this again and refer to it as you move through life.
The words answer different questions. Theist or Atheist answers the question, "do you believe in one or more gods, or in the lack of gods?" Gnostic and agnostic answers the question "do you know that X is true, or is it unknown, or perhaps not even possible to know?"

As SUH stated, think of it as quadrants:
Gnostic Theist - believes that god or gods exist and knows it to be the case
Agnostic Theist - believes that god or gods exist, but it is either unknown, or even unknowable if this is the case
Agnostic Atheist - believes that no gods exist, but it is either unknown, or even unknowable if this is the case
Gnostic Atheist - believes that no gods exist and knows it to be the case

you should be using two words to describe your own system of beliefs. "agnostic" is not enough to clarify, because as SUH stated, it does not suppose either a default of theism or atheism.

I realize this is one corner of one forum on one corner of the internet, but if anyone has gained a bit of insight, I sincerely hope that it will help to clarify, at the very least so that people can accurate describe their own positions in the future.

#28 Ian Fin

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Posted 03 May 2012 - 10:03 AM

View PostJookerson, on 02 May 2012 - 02:25 PM, said:


I agree with Jookerson. Stop asking random guests about their beliefs, if you want serious answers about atheism, get a serious atheist. And if the king of all atheists is open to being on the show, do it, have you not seen this man on Fox news? This will be an amazing show.

#29 jughead

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Posted 03 May 2012 - 11:08 AM

View PostIan Fin, on 03 May 2012 - 10:03 AM, said:

I agree with Jookerson. Stop asking random guests about their beliefs, if you want serious answers about atheism, get a serious atheist. And if the king of all atheists is open to being on the show, do it, have you not seen this man on Fox news? This will be an amazing show.


That guy is my hero! Please for the love of non-god get this guy on the show! If not just to wrangle in Aaron!

#30 rockydocky

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Posted 03 May 2012 - 06:00 PM

Any whoodles....


Posted Image

#31 SUH

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Posted 05 May 2012 - 11:15 AM

View PostIan Fin, on 03 May 2012 - 10:03 AM, said:

Stop asking random guests about their beliefs, if you want serious answers about atheism, get a serious atheist.


I don't think the show is best served by serious answers. It's more interesting to hear personal opinions on the subject.

But I agree in part due to the fact that every guest seems to not know the definition of atheism or agnosticism. David tries, but he uses the popular social definitions instead. This is kind of frustrating, because it ends up sounding like The View or a Faux News Pogrom. I love to hear about guests beliefs, but minimally after several conversations that totally failed to use the correct definitions, it's time to snap to it, get it right, at least definitionally so y'all can then proceed to make it silly.

#32 goldbug12

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Posted 05 May 2012 - 09:35 PM

I know you guys might have already recorded this episode but I would really like some more clarification on her claims about the flashlight and anything faster than light.

#33 goldbug12

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Posted 05 May 2012 - 09:50 PM

And I'd also like for the god and athiest camps to stop fighting, believe what you want and associate with people with like mindsets. It doesn't matter what happens when we die - we're all going to do it eventually and we'll find out then, or we'll all just be dead. Either way, it's better not to spend whatever time we have on earth proclaiming our righteousness when truly, neither of the two camps really knows what they're talking about.

This is why science is not philosophy, or religion.

Get off of your soapbox and help people. And try to do it without imposing your bullshit moral code on them. Athiests I'm looking at you too!

#34 SUH

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Posted 06 May 2012 - 08:27 PM

Yes my friend, whatever beliefs we may have we're all human beings here on the planet for a blink of the universe's and/or God's eye.

#35 The Beloved Leader

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Posted 22 June 2012 - 07:34 AM

I'd like to second @tbain. This was my first time listening to the podcast and although I'll listen to a few more episodes, your show needs to consider its sources. I'm a Ph.D. candidate in cognitive science (not physics) but I knew enough to know that she was incorrect on most of the points that @tbain mentioned above. I was also irritated with the inaccurate portrayal of the differences between Newton and Einstein's theories. It should be clearly explained to any audience that both theories are mathematical models and that mathematical models can be described in terms of their accuracy in describing empirical data. Newton's models are simple and work exceptionally well when discussing certain distances. Where Newton's models begin to break down is at large distances and with very large masses. This binary concept that the public has of scientific theories being right or wrong is a huge misconception that really needs to be better explained by the scientific community and Christina, unfortunately, just didn't pul her weight here.

#36 Colin Fraser

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Posted 06 December 2012 - 02:02 PM

Well I'm only 7 months late; but I thought the episode was pretty good and my real only problem which matts has mentioned was Christina's dismissal of Aaron's exoplanet discovery method:
She mentions watching planets and waiting for a transit as the best method, but as you can imagine the probability of seeing this in 3D space is very rare; and while it has discovered planets before, there are better methods.
Primarily the one that Aaron referred to, wobbling. Gravitational orbits affect both bodies, not just the tiny planets. And with bigger planets like Jupiter, you can see the small orbit of the Sun that Jupiter causes: http://en.wikipedia....File:Orbit2.gif
And so if you see red/blueshifts, evidence of this wobbling you can infer the size and orbital radius of an exoplanet.