1

That CAN'T be true! / ...that the sun generates about as much energy as a compost heap.

« on: 11/04/2011 18:46:23 »

"Peak power production in the Sun has been compared to the volumetric heats generated in an active compost heap"

http://en.wikipedia.org/wiki/Sun

2

Cells, Microbes & Viruses / How does epigenetics impact our DNA inheritance?

« on: 10/04/2011 23:41:22 »

As I understand there is some kind of binding of methyl groups onto the DNA which can deactivate different segments of it.

Does this deactivate it for life, or just until the cell meiosis?
What causes these methyl groups to attach; is it random?

3

Cells, Microbes & Viruses / What parts of the cell are inherited?

« on: 10/04/2011 23:37:34 »

When we are conceived, what parts of our cell machinary are inherited from the parent cells.

Obviously, the DNA.
Less well known, the mitochondria seem to be passed down from female to female. Presumably they have their own method of reproduction?
I would like to identify any other components that are inherited without the use of DNA.

4

That CAN'T be true! / Invitation to live on Venus?

« on: 10/04/2011 11:29:25 »

At about 55km above the surface of venus the pressure and temperature are very close to STP.
Also an earth like atmosphere would provide a lot of lift, as the Venusian atmosphere is a lot denser.

This makes it in concept possible to think about starting a colony on Venus in a "floating city".
Needless to say, a great many technical hurdles remain unresolved.

5

Physics, Astronomy & Cosmology / What have they found at the Tevatron particle accelerator?

« on: 08/04/2011 00:36:57 »

Is it some new particle and new physics, (or just an inability to moderate the urge to compete with the LHC?   []  )

6

Physics, Astronomy & Cosmology / What is the simplest explanation of gyroscopic precession?

« on: 08/04/2011 00:32:59 »

What is the simplest explanation of gyroscopic precession?

I apply a force perpendicular to the angular momentum and it always gets defected by 90° regardless of the angular momentum magnitude?


I seemed to make some headway by considering twisting stress on a segment of the spinning mass, but I realise I'm not content with my understanding. ( ...and this is classical physics).
 

7

Physics, Astronomy & Cosmology / Why is atmospheric pressure on Venus 92 times the Earth's?

« on: 06/04/2011 22:02:54 »

Surface gravity is about the same.

Is it the composition of the atmosphere (being mostly CO2 not N2),
its density factor is aprox 2, (but that doesn't impact pressure??)

Surface Temperature is 737 K - which could give us a pressure factor of 737/232 = about 3.

Scale height of atmosphere is 15 to 20km compared with the earth's 8.9km, another factor of up to 3.

Still missing a factor of about 10 - help.

8

That CAN'T be true! / Do Planetary Climate Models of Venus compare to Earth?

« on: 02/04/2011 23:21:03 »

Venus
distance from sun, 108,942,109km
mean surface temp    460°C = 735K
atmosphere: dense

Mercury
minimum distance form sun, 46,001,200 km
maximum surface temperature 700K
atmosphere: none

Despite Venus receiving around one quarter the intensity of sunlight as Mercury, its mean surface temperature exceeds the highest temperature on Mercury.

Is this due to atmospheric warming alone, and what does it tell us about climate change on earth?

9

Physics, Astronomy & Cosmology / Why do neutrinos have to have mass to oscillate and how is energy conserved?

« on: 02/04/2011 21:54:37 »

It has been shown that neutrinos do spontaneously oscillate from one flavour into another, which has overcome the solar neutrino problem.
This is quoted as implying that they must have non-zero mass. Why does it imply that?

Secondly, when a neutrino does oscillate it changes from a particle with one mass to one with another. Where is the energy due to mass difference supposed to go?

10

New Theories / What are the top theories explaining Quantum Teleportation?

« on: 02/04/2011 21:42:36 »

Thread Assumption
1) quantum teleportation of information has been proven.
2) Some reputable physicist have some theories that might resolve the incompatibility of this observation with a relativistic speed limit c.

a) What are these theories?
b) What are your personal/non peer reviewed theories? (please distinguish from a).

11

Physics, Astronomy & Cosmology / How much energy holds nucleons together?

« on: 30/03/2011 01:08:21 »

2) One day early man discovered fire (then, they say, he played with it).
3) But the energy density of molecular bonds (as released by fire) is dwarfed by that of nuclear bonds.
1) Perhaps we can also say of pre-fire days that kinetic energy (i.e. interactions between stable molecules) was dwarfed in terms of energy density by fire.

So, extrapolating, suppose we could access the next level down, inter-quark forces within nucleons.

How much energy are we talking about in these inter-quark bonds?
Is there a "binding energy" curve for the different nucleons according to their quark composition?
Why aren't we already building nucleon reactors?

12

Physics, Astronomy & Cosmology / What's the difference between Gravitons and Gravity Waves?

« on: 30/03/2011 00:47:37 »

Some people seem to be searching for gravitons with particle accelerators and others for gravity waves with, basically, "great big set squares".

I'm familiar with this established theory that photons are electro-magnetic waves.
But it must be wrong to confuse gravitons and gravity waves because their scale is so different?

Could any-one explain the situation?
Is it possible for both searches to be successful?


[MOD EDIT - PLEASE FORMAT YOUR POST TITLES AS QUESTIONS, IN LINE WITH OUR FORUM POLICY. THANKS. CHRIS]  [JMLCarter = apologies there - retitled again to clarify question].

13

New Theories / What's the difference between quantum entanglement and a collision?

« on: 28/03/2011 21:34:25 »

Could it be reasonable to consider that quantum entanglement is a kind of quantised collision "in progress". If not in what way is it different?

Perhaps consider
a) what would a collision be like if only discrete amounts of energy could legally be exchanged?
b) classical collisions pass momentum, whilst in an entangled system the momentum is conserved, but which member of the system gets what momentum is only defined by a later outside observation/measurement.
c) does there have to be a force involved to establish entanglement?
d) can macroscopic objects perhaps be considered to "observe themselves", forcing near instantaneous resolution of each momentum exchanges.


Basic Background:
In classical particle physics a collision is an exchange of momentum via a force which acts as the means of transmission of the energy.

In classical wave physics waves do not exchange momentum, only re-inforce or cancel in amplitude.

In quantum theory the wave function entity (assuming it's real not just a math construct) is neither a wave nor a particle, but appears to behave like one or the other depending upon how it is observed.

14

New Theories / Why is c 299,792,458m/s and not some other value?

« on: 23/03/2011 22:55:05 »

Sure the equivalence principal implies a universal speed limit; but why is it not higher or lower than it is.

c^2= 1/sqrt( permittivity * permeability )

doesn't immediately provide the answer. Understanding why free space resists motion might explain why it has permittivity and permeability at all. This could help understand why are they not higher or lower? Perhaps it is something to do with the density of virtual particles in a vacuum? What would determine this density?

Another possible explanation, if it were higher or lower would we notice? If not why not?