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(Science Daily)   Humongous telescope will be large enough to observe plants in other solar systems, follow Carrot Top's career   ( divider line 115
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16186 clicks; posted to Main » on 29 Dec 2004 at 3:09 AM (10 years ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»

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2004-12-29 02:13:58 PM  
bakarocket --

Thanks for the attempt at it. I didn't realize the speed of gravity was still so up in the here. I figured they had it pretty pegged at the speed of light which is nowhere near the case.

BiffTWC --
"Maybe, I'm a moron, but if light has no mass how is it "trapped" by the gravity of a black hole?"

If light requires space in which to travel and that space is curved back in on itself, then it doesn't necessarily require mass to become trapped. It can simply be plowing along through the space, but that space has been curved sufficiently that it can longer come back out.
2004-12-29 03:38:56 PM  
lensitational gravimation is to pork rinds


photonical burnination is to love
2004-12-29 04:07:18 PM  
2004-12-29 04:48:47 PM  
Just for the record here you guys:

Former Football Player = Jock
Still writes bad poetry = Poet
Photographer by trade = Artist

Still tracking your conversation here. Not well. Nothing to contribute, but still tracking nonetheless.

Now, granted as well, I am some sort of freak mutation of the jock/poet variety. I'm just sayin, is all I'm sayin.

Oh yeah, and as far as the graviton:

Wasn't there a Laser Interferometer that was set up to try and detect gravitational waves passing through our space/time area? Did they ever find anything through that?
2004-12-29 06:01:49 PM  
I saw on NOVA yesterday that a possible reason gravity is so weak compared to magnetic is because gravitons may not be confined to our 3 dimensions. Magnetism appears 10^33 times more powerful than gravity because of this. If this is true and we can create gravity waves at will we could use them to comminicate with aliens living in parallel universes.
2004-12-29 06:40:12 PM  
It took nine posts before getting a Uranus mention?
2004-12-29 06:44:50 PM  
bastian_74: And it would make moving furniture a hell of a lot easier. :)
2004-12-29 07:27:40 PM  
I got here way late, for various reasons, but in the hope that one or more of the experts who posted while I was sleeping may return, let me ask this: is it possible to replace the word "curvature" in describing what happens to spacetime in the presence of mass to something else? The candidate I have in mind is "compression," and I have gotten a lot of intuitive mileage (or kilometerage, for those who prefer that metric), viewing it this way.

Have no mercy on me, I can take it.
2004-12-29 11:16:06 PM  
Maybe, I'm a moron, but if light has no mass how is it "trapped" by the gravity of a black hole?

You need a more precise definition of "mass".

A moving object contains either or both of two types of energy: "rest energy", and "motion energy". It's the first type of energy that people are talking about when they use Einstein's equation, E=mc^2. In this case, E is "rest energy", and is directly proportional to the property m, or "rest mass".

Light, however, has no rest mass. All of its energy is "motion energy". However, according to general relativity, both "rest energy" and "motion energy" are affected by gravity, which is why black holes bend light beams.
2004-12-30 12:54:17 AM  
Mouser: ...which is why black holes bend light beams. does the Sun. As a matter of fact, the effect of gravity and General Relativity on light was confirmed during the solar eclipse in 1919. The effect was measured by carefully measuring the position of known stars in a star cluster near the Sun at that time.

In classical physics, mass and gravitational constant is tied together. But in modern physics, i.e., general relativity, we talk about space and time being bent around any object that posesses mass (i.e. you, sumo wrestler, or Mary Kay and Ashley). Of course the more massive you are, the more significant the effect of gravity and GR can be.
2004-12-30 06:53:50 AM  
helioquake: Ohisashiburi (or maybe not so long, just exercising my memory), and I have another theory for you.

I have read, somewhere (can't recall, I'm afraid), that if you were to find some location in space that was under little/no influence from extraneous bodies, you could propel two bowling balls (or any other round object, such as a planet) at each other, and that they would never hit, regardless of the perfection of your trajectory.

The explanation for this was that gravity has a repulsive effect as well as the standard sucking. And gravity does indeed suck, it nearly caused me injury when my ladder collapsed the other day. Never trust fiberglass.

I guess the theory must be that the trajectory's vector started out pointing at the other object, but gradually gravity's supposed repulsive force threw it off. Once you have even the slightest disturbance in the trajectory, Heisenberg's theory of uncertainty can come into play, and you can no longer rely on scientific method. But since none of this has ever been experimented, and probably won't for some time (it took Pioneer quite some time to escape the solar system, so I doubt if we'll be hitting its gravitational horizon anytime soon), we have to assume that this is not reliable.

Apparently in 1901, the French and US Geodetic surveys used two deep mineshafts, and extended weights down to the one-mile mark. According to the basic idea that the center of Earth's gravity is at..the center, the weights should be ever-so-slightly closer together than the top of the ropes from which they dangle. Apparently, that wasn't true.

This article (now with 20% more capitalization) attempts to explain or at least question this phenomena. I'm sorry that I have no motivation to delve for a more detailed or methodical article, but if you're sufficiently interested, I'm sure you'll find one. I'm just lazy today. :)

Here is another article I found that attempts to explain how dark matter might be influencing Voyager and Pioneer. Also it brings to light the stupidity of printing books for school in our modern, digital world, although indirectly.
2004-12-30 11:53:09 AM  
abdul: Apparently, that wasn't true.

I had forgotten about that. Nice reference. Have to wonder how true it is, but I heard about this a long time ago. Sounds like a grad student experiment in the making.

Also wonder about the capitalization thing. The freakier the nutjob, the more capitals they use. When they start capitalizing common nouns it's usually an indicator that Zoloft should be administered.
2004-12-30 02:54:32 PM  
SpaceButler: According to general relativity, light does indeed have mass,

Oh one addendum. The concept of 4-vector space (which leads to that E=mc2 thing) is originated from special relativity. General relativity is more about space-time. The former is far simpler to understand. There is a good paperback from Dover...I forgot its title now, but it's about electromagnetisms. It contains a very good description of special relativity as well as E&M...(or you can read the original book on relativity by Einstein himself, but that one was a harder reading, considering how much I hate differential geometry).
2004-12-30 02:57:09 PM  
Oops, my firefox is acting up on me and posted whatever was in the cache. If the moderator is around, please delete the post marked "2004-12-30 02:54:32PM" from helioquake. Thanks.
2004-12-30 06:55:42 PM  

That link is interesting, in the sense that anyone who cannot see the fallacy is not likely to be much of a success at science. If you are on the SURFACE (pardon the caps, but I am too lazy to bother with italics), of a fairly homogeneous sphere, then the gravity will SEEM to attract everything to the center of mass. But all mass provides gravitas. Imagine, for example, that Death Valley is on your right and the Sierra Madre on your left: in this case, your readings will be off. Worst case scenario: you are standing on a uniform sphere that is, beneath a certain point, hollow. Dig down and eventually you will reach the hollow innards, where, surprise surprise, there is NO gravity. Along the way, things will behave very strangely. (Likewise, could you reach the earth's center, you would find no gravity there, either. Or, rather, you would be equally attracted in all directions at once, which amounts to the same thing.)

It is no suprise to me that the French tried this, but it is a shock to see that Americans bothered, as well. Think about it for five minutes (fifty if you are French), and you will see why the plumb lines MUST diverge -- they are being attracted to opposite hemispheres. Lower them far enough, and they will curl back upwards, in opposite directions.

Hope this doesn't make anyone's head asplode, but it is so late in the thread that nobody is likely to read it.

/Anyone who buys into that article must imagine that "Armageddon" was a documentary.
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