Does the Moon's Gravity Attract Earth?

[SpaceTiger]

So does that mean that motion is acausal? Do bodies stay in motion for no reason at all? If a particle at rest is caused to move in a certain direction, what keeps it moving in the same direction after the initial force is taken away?

The "why" of Newton's Laws is answered by Einstein's equations and Quantum Mechanics. The "why" of those theories may be explained by string theory. At some point, however, you're going to be stuck with a "why" without an answer. It's just the way things are.

 

[Phobos]

The effect exists, the cause does not. The believed cause is that more light makes it easier to carry out outdoor activities.

I certainly agree that the moon does not cause abnormal human behavior through some physical mechanism.

But furthermore, I have yet to see any demonstration that there is a statistically significant increase in abnormal behavior associated with the phase of the moon. Seems to be an urban legend. But, if y'all want, please continue that discussion in the S&D forum.

 

[Phobos]

in velikovsky's worlds in collision,...

Velikovsky was a bit of a crackpot. So, let's not muddle this particular topic with his ideas. But you can discuss Velikovsky's ideas in a new topic if you want. Thanks.

 

[ohwilleke]

In favor of the lunar crime connection see here: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6440656&dopt=Abstract and
http://www.toledoblade.com/apps/pbcs.dll/article?Date=20020825&Category=NEWS03&ArtNo=108250070&Ref=AR

against see here: http://www.albemarle.org/upload/images/forms_center/departments/police/forms/04full_moon.pdf and
http://www.cincinnatiskeptics.org/blurbs/lunar-influence.html

 

[x8jason8x]

Velikovsky was a bit of a crackpot. So, let's not muddle this particular topic with his ideas. But you can discuss Velikovsky's ideas in a new topic if you want. Thanks.

at the risk of mincing, Einstein was also called a crackpot...I tend not to dismiss anything as irrelevant until it's proved absolutely wrong. I will however refrain from "muddling".

 

[DaveC426913]

at the risk of mincing, Einstein was also called a crackpot...

This is a meaningless statement. Einstein's peers calling him a crackpot and us calling Velikovsky a crackpot are apples and oranges.

(I'm not saying "How could you call Einstein a crackpot!", I'm saying the two claims are not comparable.)


Einstein had some really out there ideas, but he followed scientific rigour, and showed his results mathematically. Anyone who took the time to rigourously examine his theories would find little wiggle room (noting the lack of competing theories as testament).

Velikovsky can be demonstrably proven wrong on claims. He makes up facts, uses dicey logic, and generally manipulates his way to implausible conclusions that will never withstand critical examination. He simply can't be taken seriously.




A different example: As the word 'crackpot' can have differing validity, so can the word 'theory'. Astrology "theorizes" that stars and planets affect humans. The atomic nature of matter is also a "mere" theory. But simply giving these two things the same label doesn't make them comparable in their validity.

 

[Phobos]

x8jason8x -
No problem...just looking to keep this particular discussion on-topic.
Try checking around the archives for past discussions of Velikovsky. If you would still like to discuss his ideas, then feel free to start a new topic. Thanks.

 

[lwymarie]

does the gravity of other planets makes the orbit become not a circle, other than the factor of 'they are moving sideway'?

 

[ohwilleke]

The gravity of everything else in the region (indeed, in theory, everything else in the universe) perturbs the orbits you are primarily focused upon. The orbits aren't circles to start with and won't stay circles as a result. A perfect two body system creates a ellipical orbit. Adding additional bodies to the mix perturbs (i.e. modifies) that ellipse.

The mathematics of a three body problem is difficult. The mathematics of an arbitrarily large number of bodies interacting by Newtonian gravity alone so complex to calculate exactly that numerical approximations are generally used instead.

 

[Linkk06]

Janus, thanks for answering my question. That makes so much sense now!

Okay, you know how the moon affects the tides? Does high tide in a particular come when the moon is directly above or out (I don't know how to say it) from the area? And if so, then would low tide be exactly across the world from it?

 

[DaveC426913]

Linkk06:

Up in space astronauts float because they're far enough away from any planets or the moon that no gravity is keeping them to the floor, right?

No. (I didn't want to let this one go.)

Astronauts up in space - including in the space shuttle - are indeed affected by gravity. It is important that you realize this. It only appears as if there is no gravity because the shuttle is falling at the same rate as the astronauts inside it.

It is the same as being in a descending elevator. If you were in an elevator that was descending so fast that your feet came offf the floor, you would be in the same situation as the astronauts, but you sure wouldn't think "gravity had no effect" on you, would you?

 

[V-Tec]

How come the moon orbits facing the earth, while the Earth orbits and rotates?

 

[SpaceTiger]

How come the moon orbits facing the earth, while the Earth orbits and rotates?

The moon still rotates, it just has a rotation period that's the same as its orbital period. Here's a nice thread "tidal locking", the explanation for why we always see the same face of the moon:

https://www.physicsforums.com/showthread.php?t=67691

 

[russ_watters]

Okay, you know how the moon affects the tides? Does high tide in a particular come when the moon is directly above or out (I don't know how to say it) from the area? And if so, then would low tide be exactly across the world from it?

There are two high tides and two low tides. The high tides are on the side directly facing the moon and on the side facing directly away from the moon. This is because the moon essentially pulls the Earth away from the ocean on the side facing away from the moon.