Thread: Nebular Hypothesis

I have a big confusion on Nebular hypothesis. becose many of evidences are oppose this hypothesis.

Originally Posted by bilal.jutt980

I have a big confusion on Nebular hypothesis. becose many of evidences are oppose this hypothesis.

Would you like to be more specific about which evidence you think contradicts it?

But I wouldn't be surprised if there is some contradictory evidence. This is science, after all. We may not have all the answers.

If we look at the densties of the planets in our solar system we came to know that this arrangement is in ascending order from Sun. It well defined that in any rotatory media the most denser thing acccmulate in the center of media but our Sun have more lighter than its planets and Sun is center of our system. If this system was formed in a way that is stated by Nebular Hypothesis than Sun should have more density than its planets.

Originally Posted by bilal.jutt980

If we look at the densties of the planets in our solar system we came to know that this arrangement is in ascending order from Sun.

What?
Mercury - 5427 kg/ m³
Venus - 5243
Earth - 5515
Mars - 3933
Jupiter - 1326
Saturn - 687
Uranus - 1270
Neptune - 1638

While the denser planets do tend be nearer (which contradicts your claim, maybe you meant descending order) there's no clear relationship between distance from the Sun and density.

It well defined that in any rotatory media the most denser thing acccmulate in the center of media

What?

and the density of sun is 1408 kg/m3. and sun is centeral part of solar system by the general physics sun should have high density as its planets.

Originally Posted by bilal.jutt980

and the density of sun is 1408 kg/m3. and sun is centeral part of solar system by the general physics sun should have high density as its planets.

So.......you didn't read anything that was posted.

what??

what??

Originally Posted by bilal.jutt980

what??

So.......you didn't read anything that was posted.

Originally Posted by bilal.jutt980

and the density of sun is 1408 kg/m3. and sun is centeral part of solar system by the general physics sun should have high density as its planets.

The sun has a LOWER density than any of the first four planets, and yet is at the center of the solar system. So your idea is false.

try to understand Sun has lower density as its planents, and accordinding to Nebular hypothesis this system was formed from a rotatory medium abd its is proved that in any rotatory media the most denser thing always accamulate in center. so why Sun(central part of our system) has lower density?

Originally Posted by bilal.jutt980

its is proved that in any rotatory media the most denser thing always accamulate in center.

Where is this proved?

it is general law of physics

Can you provide a link or some reference to where this general law of physics is described.

o Strange you should look at the centrifugal force and observed centrifuge machine.

Originally Posted by bilal.jutt980

o Strange you should look at the centrifugal force and observed centrifuge machine.

Well there are several problems with this:

1. This is an example not a "general law of physics"

2. A centrifuge separates material with the densest stuff collecting furthest from the center of the centrifuge.

3. So this example appears to contradict you.

4. The solar system is not, and never has been, a centrifuge.

Let's take another random example. A hurricane. Guess what: the lowest pressure (lowest density) is at the centre. Seems like your "general law of physics" is broken by quite a few examples.

If this really is a "general law of physics" then it should have a name and you should be able to point to, say, the Wikipedia page describing it.

I suspect it is something you have made up.

bilaljutt.980,
You seem to be confused as to what the nebular hypothesis is.

We begin with a collapsing cloud of gas that is reasonably well mixed. (There are some subtle departures from this that are interesting, but not relevant to the overview.)

As it collapses it heats up. The central mass forms a spherical shape, the proto-sun. The remaninder forms a disc. Further heating occurs as a consequence of radiated heat from the proto-sun.

At some point material begins to condense out the disc. At this point the disc is still pretty well mixed, so its composition is the same throughout. More refractory materials condense out close to the proto-sun, lower melting point materials further away. Particles begin to accrete into planetesimals and protoplanets. Runaway accretion occurs with the cores of the giant planets and they attract gas. This is just in time for then the sun enters its T-Tauri phase and most of the gas in the system is swept away.

Where in that sequence of events should we have a density distribution that you say is required. The density distribution matches expectation rather nicely.