Wednesday, January 07, 2009

Death by Black Hole

I love to listen to Neil DeGrasse Tyson when he speaks about astro-physics. He has an uncanny way of making the the working of the cosmos something even the most jaded person would find interesting and humorous.

Here in this short, Dr. Tyson talks about what it would be like to fall into a black hole. The short is from a much longer talk that takes in many different ways the cosmos is trying to kill us as we speak. Yes, he is that fun to listen to. If you like the short, click on the article title to be directed to the longer piece.

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Dave Tackett said...

Completely agree with you here, Paul. Tyson is an excellent speaker and his astronomy discussions are always enlightening (except about Pluto's status, where he is too militant for such a complex issue).

Beam Me Up said...

I think all militant opinions about Pluto's status are emotional. Planetary definitions have had a schizophrenic application over the last few decades. The way I see it is that there has to be some sense of uniformity. For example Pluto was considered a planet but Eris and Ceres were not? Plus Charon was considered a moon?! This is really odd when you consider Eris is some 30% larger than Pluto... It's not that there is a problem with Pluto being a planet...its that everything larger must be as well huh? We had a possibility of having not 10 but literally dozens of planets. But finally it was not the size that was the determining factor. A true planet must yes, be of a certain size, but more importantly it must behave as a planet. By that I mean the object must have a reasonably circular orbit and it must confine itself to that orbit which does not cross the orbit of another body. So even if Pluto was much larger it still would not be a true planet because of its' eccentric orbit.

Dave Tackett said...

All very good points. However, there is another side to all of them. The eccentricity rule seems arbitrarily applied to Pluto, but not to extra-solar planets, many of which have greater eccentricities than Pluto but are completely non-controversial in their planethood.

Eris wasn't discovered until 2003 and until it and Pluto were labeled "dwarf" planets, it was not officially classified as being not a planet; it was under review.

As for the number argument (used by Tyson), however, it is completely unscientific. However many planets there are, that's how many there are. We haven't stopped classifying extrasolar planets as such because there are now too many to easily remember.

Personally I think we should wait until 2015 when Dawn and New Horizons visit Ceres and Pluto, giving us our first hand look at "dwarf" planets before carving any definition into stone.

Tyson, whom I really do otherwise like, angered me with his "Pluto's not a planet; get over it." statement on a Science channel documentary. Debate, like we're having, is science, the use of authority to mandate a decision is academia.

A final thought, why is Saturn, a blob of gas that is less dense than water considered a planet.

Beam Me Up said...

Good points all, however I have to take issue with the "arbitrary" application of eccentricity to Pluto's orbit. It IS eccentric. Any of the bodies further out that have likewise eccentricities aren't likely to be considered planetary bodies either. As for extra-solar planets...really apples and oranges, we know they are there, but little more than that. The planetary definition for Sol are in my mind housekeeping in nature. Because in the end it wasn't about a few more planets. As our deep space detection ability improves there is every likely-hood that that the number could grow into the hundreds. No matter how long you put it off - at some point there will be a break that will define these "planets" as one thing and these "other planets" as something else. As for Saturn, A planet is not a mass thing. It inhabits it Keplarian position and despite an idiosyncratic nature, is a planet under any definition. The real problem is that Pluto held it's position for quite a period. The label was applied when very little was known about its overall nature. Had it not been a binary, it may never had been discovered until much much later (Pluto's mass alone would not have been enough to cause the perturbations that astronomers had discovered.) So I suspect that no matter what the title, Pluto will continue to be the Planet Pluto for many people for some tome to come.

Dave Tackett said...

Hi Paul.

Sorry I wasn't too clear. I know Pluto's orbit is eccentric, I think that's been known since long before either of us were born. And that's part of the problem for me. If eccentricity disqualifies Pluto now, why didn't it for all those decades? If eccentricity disqualifies a "world" from being a planet around our sun then why doesn't it around other stars?

I also have difficulty with the objections based on there being too many planets. There are millions of insects, yet "insect" is useful scientific definition. There are countless billions of stars, yet "star" is a clear and useful definition. Why would there being dozens of planets make the definition "meaningless" as the anti-Pluto people maintain?

As you note "planet is not a mass thing." But why isn't it? For classification, aren't intrinsic properties of an object more important than behaviors. If biologists thought like some astronomers then dolphins would be classified as a fish because they swims like fish, while their being warm blooded would be considered irrelevant.

It is important to remember that in 2006 the IAU first defined Pluto, Charon, Ceres, and Eris as planets, but the anti-Pluto group screamed bloody murder until the decision was reversed, which is the reason their is so much controversy within the scientific community.

Let me also state clearly that I personally do not care if Pluto is classified a "planet" or a "duck" for that matter as long as the definition of planet meets two reasonable criteria.

1. The definition is clear, measurable, and universally applied. For example, the definition of a planet orbiting Sol cannot be different than the definition of a planet around Tau Ceti or Barnard's star.

2. The definition is such that the four most "planet-like" of the planets, Mercury, Venus, Earth, and Mars would be considered planets no matter where you moved them - as long as their physical properties remained similar.