Your thoughts on Neil deGrasse Tyson

[Night FM]

He's said some stupid stuff that doesn't hold water.

[studiot]

40 minutes ago, HopDavid said:

Please reread what I wrote.

Centripetal is towards the center of rotation. Centrifugal is outward. 

ω^2 r gives what seems like outward acceleration in a rotating frame.

m ω² r is an imaginary force , introduced by D'Alembert to tranform the dynamic problem using Newton's Laws

Newton:  F= ma    is the equation to be solved

into one of static equilibrium.

D'Alembert  ƩF = 0  is the equation to be solved.

Where bold type denotes vectors in both cases.

[HopDavid]

2 hours ago, swansont said:

Outward is what you exert, but Newton's laws are about what is exerted on you. The force on an object moving in a circle (such as a rotating space station) is toward the center of the circle. 

I am talking about m ω² r.

Huygens called this centrifugal force. Newton called this centrifugal force. Even Tyson calls this centrifugal force (one the of the occasions I agree with him!).

In the case of orbiting bodies it is gravity that provides the centripetal force.

Gravity is m μ / r².  This is often different from m ω² r.

Only in the special cases of circular orbits is m μ / r² = m ω² r

So I would prefer to continue using the term centrifugal acceleration or centrifugal force. I have already acknowledged that it is actually inertia in a rotating frame. If you are in a rotating frame it is convenient to call inertia a force.

But if you like I could call it artificial gravity

Sooo... Isn't it freshman physics that artificial gravity in a rotating space station is m ω² r ?

Notice that I bolded the exponent. Evidently in your freshman class the label you gave it is more important than the exponent. Tripling the RPMs does not triple the weight as Tyson claims.

 

[swansont]

21 minutes ago, HopDavid said:

So I would prefer to continue using the term centrifugal acceleration or centrifugal force.

The force the floor exerts on a person in a rotating space station is toward the center of the circle, i.e. it is a centripetal force.

But it’s your prerogative to be wrong.

[HopDavid]

48 minutes ago, swansont said:

The force the floor exerts on a person in a rotating space station is toward the center of the circle, i.e. it is a centripetal force.

But it’s your prerogative to be wrong.

How about m ω² r ?  Is that wrong?

Are you okay with Tyson's  m ω r ? Do you think tripling RPMs triples weight?

 

[exchemist]

7 hours ago, HopDavid said:

How about m ω² r ?  Is that wrong?

Are you okay with Tyson's  m ω r ? Do you think tripling RPMs triples weight?

 

This is getting a bit silly now. The disagreement is quite clearly about the legitimacy of the term "centrifugal force", not the formula.

You can specify a rotating frame of reference if you like, but if you try to apply Newtonian dynamics in a non-inertial frame  you get into a lot of complications:

 https://phys.libretexts.org/Bookshelves/Classical_Mechanics/Variational_Principles_in_Classical_Mechanics_(Cline)/12%3A_Non-inertial_Reference_Frames/12.05%3A_Newtons_Law_of_Motion_in_a_Non-Inertial_Frame

Which is why it is in most circumstances not a good practice. 

Edited Wednesday at 09:50 AM by exchemist

[swansont]

8 hours ago, HopDavid said:

How about m ω² r ?  Is that wrong?

Are you okay with Tyson's  m ω r ? Do you think tripling RPMs triples weight?

You persist in asking me about issues I’m not addressing. Your obsessions are not my obsessions.

[studiot]

8 hours ago, HopDavid said:

How about m ω² r ?  Is that wrong?

Are you okay with Tyson's  m ω r ? Do you think tripling RPMs triples weight?

 

Did you not understand my post ?

 

I note that 'Orbital Mechanics' is listed as your favourite subject.

 

Are you aware of this textbook ?

[HopDavid]

9 hours ago, swansont said:

You persist in asking me about issues I’m not addressing. Your obsessions are not my obsessions.

"Your Thoughts On Neil deGrasse Tyson" is the topic of this thread.

And I've offered my thoughts. In my opinion Tyson is a source of misinformation. 

To support this I've offered examples of Tyson making wrong claims. Including an example of Tyson botching basic physics.

You took issue with one of my terms and diverted this thread into an off topic tangent.

I've made a separate thread: Lamentable Langrange Articles. We can argue over verboten terms over there.

In this thread the topic should be our thoughts on Neil deGrasse Tyson.

[swansont]

1 hour ago, HopDavid said:

"Your Thoughts On Neil deGrasse Tyson" is the topic of this thread.

And I've offered my thoughts. In my opinion Tyson is a source of misinformation. 

And you’re entitled to your opinion. But you keep specifically engaging me on subtopics I have not commented on. That’s rude.

 

[HopDavid]

1 hour ago, swansont said:

And you’re entitled to your opinion. But you keep specifically engaging me on subtopics I have not commented on. That’s rude.

 

In this subthread it was you who engaged me.

I gave an example of Neil botching basic physics. Link. Which was quite on topic in this thread on Neil Tyson.

To refresh your memory I was talking about Neil's claim that tripling rotation rate triples artiflcial gravity. A flub that shows incompetence in basic physics.

You jumped in with an irrelevant comment that you seemed to think refuted what I said. Your attempt at a gotcha does not make Neil's flub go away. 

I get it. You'd rather not talk about Neil's errors in this thread on Neil Tyson.

[swansont]

11 minutes ago, HopDavid said:

In this subthread it was you who engaged me.

To specifically point out an incorrect statement. I couldn’t resist the irony.

Quote

You jumped in with an irrelevant comment that you seemed to think refuted what I said.

You should limit yourself to what I actually said instead of trying to read more into it. I only objected to your use of incorrect terminology. Objecting to one point should not be taken to be an objection to any other points.

19 minutes ago, HopDavid said:

I get it. You'd rather not talk about Neil's errors in this thread on Neil Tyson.

As I said, I'm not all that familiar with his work, other than his tendency to be overly pedantic. Also not a fan of this form of stalking.

[HopDavid]

On 5/13/2024 at 4:52 AM, Otto Kretschmer said:

Can NdGT be called a scientist in your opinion, given that he's hardly published anything in 30 years? He obviously trained as a scientist but an average practicing astrophysicist publishes more papers each year than he did in his entire career.

What's your opinion on the matter?

Also, should he be talking about stuff that is outside his area of expertise? I remember him in a YT video about depression saying something like "we already know which chemicals make you happy and which dont", which is wrong since we know very little about what causes depression. Do you know any other situations when he was wrong?

 

Continuing with the question "Do you know any other situations when he was wrong?" ...

So far I've listed some of Neil deGrasse Tyson's basic flubs in physics and astronomy. There are even more embarrassing errors when he ventures into realms outside his supposed area of expertise.

Tyson is really, really bad at history.

See Tyson's video My Man, Sir Isaac Newton.

Tyson has Newton explaining elliptical orbits and single handedly inventing calculus in just two months, on a dare. All before he turned 26.

It was in Principia that Newton explained elliptical orbits and it was Edmund Halley's famous question that prompted Newton to write Principia. I'm guessing this is the encounter Tyson is trying to describe.

Halley asked his famous question in 1684 when Newton was in his 40s. Seven years after Newton worked out that inverse square gravity implies Kepler's laws. So, no, Newton didn't work out planetary orbits on Halley's "dare".

Newton started thinking about gravity and planetary motion in 1665 and made his break through in 1677. Link. It took him 12 years. Not two months as Tyson claims.

Newton did do his calculus work before he turned 26. This is one of the few things Tyson gets right. But obviously not because of Halley's "dare" made nearly 20 years later. And it was not a two month effort.

Both Newton and Leibniz built on the efforts of Fermat, Descartes, Kepler, Cavalieri, Wallis, Gregory, Barrow and others. These men laid the foundations of modern calculus in the generation before Newton and Leibniz. Historian Thony Christie looks at this in his essay The Wrong Question. Christie argues (effectively in my opinion) that calculus was the collaborative effort of many people over many years.

Thony Christie also does an entertaining critique of Tyson's timeline in his piece Why Doesn't he just shut up?

Although wildly inaccurate Tyson's Newton stories seem like a harmless piece of fictitious history. They are actually flattering to Newton.

But then Tyson goes on to use this to slander Newton.

And this is the reason I invest time and effort calling out Neil's incompetence. I don't really care if he tells his pseudo nerd fans there are more transcendental numbers than irrationals. But Neil's revisionist history is a serious offense. And I am trying to make his revisionist histories widely known.

 

 

[Phi for All]

5 hours ago, HopDavid said:

And this is the reason I invest time and effort calling out Neil's incompetence. I don't really care if he tells his pseudo nerd fans there are more transcendental numbers than irrationals. But Neil's revisionist history is a serious offense. And I am trying to make his revisionist histories widely known.

!

Moderator Note

Five pages on the subject seems sufficient, especially since we're now attracting those who have vested interests and want to avoid soapboxing. Thread closed.