Astronomy and Cosmology

I've bought a book called "50 Physics Ideas You Really Need to Know." In the section on Kepler's laws it states this. "A planet in orbit twice as far away from the sun as the earth would take 8 times longer to go around." Is this correct? I did a little calculation using the equation and it didn't work out. I then looked across other websites which stated it was indeed 4 times as far way would induce an 8x increase in time. My calculations also rung true with this. (I used square root semi major axis of the ellipse cubed.) Is the book wrong or am I misinterpreting it?

Why does a stable galaxy or planetary body create discs shapes rather than ball shapes? Saturn seems a prime example of this, phenomena, why would gravity seemingly work on only one plain?

In the 1670's, the Danish astronomer Ole Roemer figured out the speed of light by knowing the distance from earth to Jupiter. How could he or anyone else back then figure out the distance of any of the planets?

I love science programs, but my pet peeve is when they just state facts without giving a clue HOW they know it. For example, they will always say our Sun will last for a few more Billion years before swelling into a red giant and destroying the inner planets, probably including Earth. How do they know the sun will last so long? Maybe they are way off, and the Sun will become unstable in Millions or even thousands of years from now.

Hello all, I am new to this forum and i know little about physics and the universe. However, i do have a keen passion for understanding how the universe became to be and whats actually out there (dark matter and such). Anyway after taking into consideration all the different theories (brane worlds, big bang etc) about what the universe is and how it came into existence i formulated my own theory, based on size and perception. 1metre to humans could be a millimetre to something much larger and the larger you go the smaller the metre becomes until eventually the 1 metre cannot be measured because it has become so minute and you have become so large in proportion to …

I'm not really sure how to word this. It may come off sounding like "captain obvious" or it may be full of scientific holes. But I was just thinking the other day about "reality" and what "is". What we know here on earth is material - we've got tangible things to touch. We can move our hand through the air and feel the resistance. We can hear sound. We sense being glued to the earth. We can feel water, and eat food, and see sunlight. All because what we have around us, has "Substance". The atmosphere is dense with air pressure and microscopic objects which create that resistance when we move (wind). We can hear because sound has physical substance to travel from…

Why doesn't the moon crashes into the earth or the earth into the sun?Is the answer same as for the question "Why doesn't the electron meets with the nucleas loosing its kinetic energy, in an atom?"?

From the Virial Theorem, [math]K = -\frac{1}{2} U[/math] [math]\frac{M k_B T}{\mu} \approx \frac{3}{10} \frac{G M^2}{R}[/math] [math]\therefore R \; T = \frac{3}{10} \frac{G \mu}{k_B} M[/math] Now, the Luminosity, radiated away as heat: [math]L = 4 \pi \sigma R^2 T^4 = \frac{4 \pi \sigma}{R^2} \left( R \; T \right)^4[/math] is balanced by the release, of GPE: [math]L = -\frac{dU}{dt} = \frac{3}{5} \frac{G M^2}{R^2}\dot{R}[/math] Er go, [math]\frac{4 \pi \sigma}{R^2} \left( R \; T \right)^4 = \frac{3}{5} \frac{G M^2}{R^2}\dot{R}[/math] [math]4 \pi \sigma \left( \frac{3}{10} \frac{G \mu}{k_B} M \right)^4 = \frac{3}{5} G M^2 \do…

Are anti-matter particles ever-so-slightly more massive, than matter particles ? I understand, that our universe contains 7x as many protons, as neutrons, because the former are less massive, and so were 7x more numerous, at the temperature, when baryons became bound into nuclei, i.e. Boltzmann factor [math]e^{-\frac{\Delta E}{k_B T}}[/math]. If the matter-antimatter asymmetry, related to the baryon-to-photon ratio [math]\eta \approx 10^{-10}[/math], arose when the universe was approximately the temperature-equivalent of Weak bosons [math]\approx 100 GeV[/math], then a massive difference of a few eV, conceivably comparable to neutrino masses, could account for the matte…

All stars rise from the east except at the poles. However, it is hard to determine whether the moon comes from the south-east or the north-east even when the relative positions of the earth and the moon is given. Is there anybody who has a clever method to determine the direction in which the moon rises?

Now, if that other big unfalsifiable massive particle we call the Higgs Boson is the particle that imbues all other particles with their mass, what imbues the Higgs Boson with its mass? Higgs theorists are pulling their "pud". The Higgs is an ad hoc addendum that is a poor band-aid for the kink it was supposed to fix. Just what was that, anyway? Oh yeah, no explanation of "mass" in the standard model. Higgs is not really part of the standard model (yet). If the Higgs is not found, they will simply add in another ad hoc splint. The standard model will not collapse. Eventually, they'll get it right, though, I'll bet. Funny, there is no explanation of the origin of grav…

Soon after the Big Bang, light elements were synthesized, from primordial protons & neutrons, by "neutron capture" reactions. According to BBN theory: According to direct observations of space, there are (relatively) high levels of surviving D; and (relatively) low levels of Li: Thus, the following nuclear reactions occurred: but not: QUESTIONS: Qualitatively, is the Lawson criterion applicable, i.e. the amount of fusion that occurred, when the primordial plasma was "singed" in BBN, was proportional, to the product, of baryon density during BBN, multiplied by the time of BBN, i.e. [math]n \tau[/math] ? (I understand, that…

I have an idea for a way to collect space junk that our atmosphere is full of, one piece at a time. First, we start out with a command unit which will be capable of doing the majority of the work flying around to position itself to capture each item, towing the junk out of orbit, etc.. This will be connected to a large net of extra strong, highly elastic material that will absorb much of the energy of the orbiting junk. Around the net, you will have a small number of small, rudimentary pods which will be equipped with small thrusters to enable you to spread themselves out in a formation enabling you to catch the junk. All of the pods will need to be extremely strong i…

GR says A "ball of particles" vaguely resembles a star. Er go, as stars plunge in towards SMBH, at the centers of galaxies, they would plausibly become tidally compressed ? If so, then such tidal compression could possibly "squeeze the star" so as to induce faster fusion, and spark a Nova-like or Supernova-like explosion ?

If gravity is produced from matter, why does it increase when you dig further down into the earth? Shouldn't there be less matter under your feet? If you were able to dig very far down, shouldn't the matter above your head be pulling you up... Lowering the force under your feet? If this isn't the case, does gravity's pull come from the center point of an object? Maybe because gravity is the lack of space. I think I've heard that before. The force of gravity on the earth seems to always be pullilng me straight down. But the earth is also very wide. Am I also being pulled in all directions? What effect does this have on objects?

In his book 4th Dimension, Rudy Rucker says that matter & antimatter, induce (hyperspatial) curvatures, in spacetime, in "opposite" (hyperspatial) directions. From a Flatland perspective, if matter causes the rubber sheet to "sag down", then antimatter would cause an equal-but-opposite curvature "up". This is so, that when matter & antimatter combine, the resulting curvatures cancel, back into flat spacetime fabric. However, photons are their own anti-particles. Thus, any curvatures caused by the mass-energy-equivalent in photons, must be able to "self-cancel". Does that imply, that, whereas matter & antimatter cause curvatures of constant "sign"…

I understand, that our universe, at present epoch, is comprised of matter particles, in the following (approximate) ratios: [math]7 e^{-} + 7 p^{+} + 1 n^0 \longrightarrow 6 H + \frac{1}{2} He[/math] Now, if our universe began as "pure raw energy", i.e. photons; and if those photons pair-produced matter / antimatter, e.g. [math]\gamma \rightarrow \bar{e}^{+}e^{-}[/math]; then matter / antimatter "must" have emerged in equal (equally enormous) quantities. Then, negatively charged matter [math]\left( e^{-}, d^{-\frac{1}{3}}\right)[/math], and positively charged anti-matter [math]\left( \bar{e}^{+}, \bar{d}^{+\frac{1}{3}}\right)[/math], "must" have exerted power…

I have recently watched a talk given by Strauss called "universe from nothing". It was pretty insightfull but brought a question to mind about the expansion of the universe. In the talk he layed out a scenario of what hubble observed with a grid of dots. Every dot represented a galaxy. When overlapping a grid that was observed at a later time with a grid previously observed you could see that the dots expanded outward from our galaxy, and that the further out the galaxy, the greater the rate of expansion. He showed that this was true, not just from our galaxy's stand point but with observing from any galaxy. Giving the effect that whatever galaxy the observer stood on wou…

Could black holes actually be quark stars? If not, then are quark stars possible and/or predicted to exist?

The number of stars, of mass [math]M[/math], decreases with increasing mass, according to a power-law, [math]N(M) \propto M^{-\alpha}[/math], where [math]\alpha \approx 2[/math]. And, the lifetime of stars, defined by the stars' ratio of mass to luminosity, decreases with increasing mass, according to a power-law, [math]\tau(M) \propto M / L(M) \propto M^{-\beta}[/math], where [math]\beta \approx 2[/math]. (Note that the mass-to-light ratio, observed by astronomers, is a direct measures, of the effective age, of the stellar population.) Er go, the number of stars, of lifetime [math]\tau[/math], can be calculated [math]N(\tau)d\tau = N(M)dM[/math] [math]N…

It stikes me that the one thing Drake forgot in making his equation is the moon and the stability it provides. Surley this must be factored into the equation as time is very much a factor in the evolution of life let alone intelligent life.

Norbert Weiner: —- ‘Information is information, neither matter nor energy. Any materialism that fails to take account of this will not survive one day’. The dimension of intent or will, which is a property of a conscience mind, in order to have any kind of ‘Information’. ‘Information’ cannot be created without intent or will. No man can figure out ‘The Universe and Matter’, on an account of The ‘Information’ (Your ‘Knowledge’), is nothing but The ‘Distorted Feelings’ filled by The Mind into You ‘Six Senses’ during its act of perception, as willed by The Maya. The above mention act is taking place in The ‘Form’ (The Body) that is being shared by three chara…

I once read that the expansion of the universe is the only thing that is faster than light (although it's not technically a speed?). It was in a BBC focus magazine. By my reckoning because of this, distance objects light will never reach Earth. Yet stories come up in the news of far fethced galaxies seen from earth and some quasars too? If this is true then does anyone know what point we can see back too before light will no longer reach us, and at this point what would we see if say a galaxy was at this exact distance from earth. Would the light from it stay the same? Or would the apparent galaxy time perspective from earth speed up?

I always under the impression we couldn't find out, we could only judge it in relation to another point, say we are moving at speed A to Galaxy 1 but at speed B to Galaxy 2 Consider a light beam (or a photon) being sent from Earth to a detector on the Moon. Our galaxy has to be moving and in some direction through the universe (or extremely likely to be) as others are coming towards us (andromeda) and others are moving away (not including the expansion of the universe where all distance galaxies appear to be moving away) I was thinking if we sent two light beams to a detector on the moon at opposite points on the earth then the time it would take to get their w…

During the formation of a solar system do the planets manage to form before the star ignites? Would the bubbles blown from new stars and the solar wind not blow gas and dust away if planets hadn't already formed?