alext87

Does anybody know of a exoplanet that is potentially habitable (Earth-like) that has been detected using the doppler method (wobble method) and the transit method?

Some of the points Amrit is suggesting completely contradict what Professors of Physics have stated in their books! So I will trust the Professors.

Anyway in my reading I have come across an equation as follows:

T=(d/c)(d/R)^3 which can be used to estimate the time required for the binary system to coalense.

d - distance between centre of mass of the stars

c - speed of light

R - Schwarzchild radii

Can anyone please find values for d and R for the Hulse-Taylor binary? Does the value of d have to be the average? How can I work out the average because the velocity of the stars varies over one orbit - when d is small velocity is larger? Is the value of R to be used the schwarzchild meant to be the average of the two neutron stars? Thank you very much for all your help so far I really appreciate it.

Thank you all for your comments and the links they have been very helpful. I particularly like to think of the entire system as a dynamic equilibrium but can anyone quantify (give a value to) the energy that is lost from the Hulse-Taylor pulsar binary from 'gravitational waves' as predicted by relativity? I appreciate that gravitional waves may be the wrong language to use but can not think of a better phase to describe it. Thank you.

In my lessons we have come across the Hulse-Taylor binary system. I have been 'researching' about why the binary system spirals in towards the common centre of mass and believe it is to do will gravitational waves produced by large accelerations of large masses in its orbit.

However, I am interested to have a simple understanding of how general relativity predicts gravitational waves and how to estimate how much energy is lost to them over a given time or orbit. By simple I mean with a mathematical base but not high university level please. I would be really grateful because it is hard to find sufficient explanation that is at my level on the internet. Thanks

As (diameter of crater/2)^2 = (radius of the steel ball)^2 + Radius of steelball - depth of crater)^2

which is just the equation of a circle.

There is a definite relationship so that if you know diameter of the crater you also know the depth.

I am doing some analysis of results from an impact crater caused by steel balls. I am measuring the diameter of the impact crater and need to link it to the volume of the crater using the volume of resolution. Can anybody help I have a formula that I derived it is correct?

Volume of moved by impact = (2/3) π r3 – (1/12) π(4r2-D2)3/2

where r is the radius of the steel ball and D is the diameter of the crater.

This i think is linking the diameter of impact crater to the volume moved...

I also have two other calculus problems:

I need to find out the surface area of the crater in terms of the diameter of the impact crater can anybody help???

Then I need the rate of change of surface area with respect to diameter and then to depth???

These problems are beyond my mathematical skills...

The gravitational constant is 6.67 x 10^-11 and is the constant which is applies across the whole universe. The gravitational constant does not change as object get further away from each other however the force of gravity does by the inverse squared law.

Earlier somebody stated that gravity has no velocity however, if the sun was removed suddenly the Earth would continue in the same orbit (as if still orbiting around the sun) for 8 more minutes. The Earth would go dark and at the sametime the Earth would change course!!!!

Surely as a explosion occur the lighter parts travel away from the centre at greatest velocity. Therefore after a given time are further away from the centre of the explosion. Therefore surely we can locate the position of the Big Bang by measure where most of the mass is and therefore this is the position of the Big Bang. How come we are not therefore able to say where the Big Bang occurred?

We have just been learning about elliptcal orbits of comets and there was a computer model of elliptcal orbits and it showed them slow changing orbital paths so that the oval shape of the orbit slowly rotates around a point and eventually the comet/planet maps out its original path.

How can this be if we continue to see the same comets flying past the Earth every 100years or so surely we should only see them every 1000years or so?

not very clear...SORRY but I'm very confused.

How about this for an explanation? The distance between the Earth and the Sun is increasing but the whole universe is expanding so is the speed of light, our rulers all all measuring equipement. The only reason we are able to measure the change in distance from far off galaxies is because that part of the universe is expanding in a different plane/direction away from us! I don't know is this is physically sound but nice idea!

Huygen's wavelets considers every point on a wavefront as a secondary wave emitting source which therefore creates a new wavefront which has propagated away from source.

However, there is something wrong, if every point on a wavefront is a secondary wave emitting source why does the new wavefront go backwards (towards the initial emitting source)?

Does anybody have a explanation?

every function at every point except at infinity has a gradient therefore every function is differentiable as long as you can prove it does go to infinity - is this statement correct?

Yeah, we could be just keeping the bad genes in the system and therefore moving backwards as they spread further into the gene pool.

Surely as beautiful people tend to go for beautiful people and smart people with smart people and tall people for tall people. We will end up will different groups (classes) of people. eg. group of really tall people etc...

The stress of waiting to see if the cream is dewrinkling you will add on more years than the cream will take off. Just keep active!

Humans cannot be evoluting as there are too many in the population to get a complete change in the gene pool and everybody regardless of the fitness makes it to reproductive age.

Therefore, does this mean that we are just waiting until another species catches up or are we now here for ever? without natural disease do you think humans could ever be competiting for food and shelter again?

In a million years will we have changed?

I think that it could be used to reduce the amount of disease and allow parents more choice over their baby eg. they have a problem and don't want their child to go through the same problems. i also think that by supporting designer babies it would allow the development of other technologies that would benefit man-kind.

However, if designer babies were possible there must be regulations on what you can actually change. It is cruel to design a baby to have anormalities.

You could do something on reaction times. measure the reaction times of different age groups, genders, interests. If people's reactions improve with practice. This could last 50pages explains biologically your results and ways to improve the reaction times of people. outliers, reactions time like 0.10s which is impossible or 1.7s which means the person had completely missed the que. There's loads there.

How can a tiny tsunami interrupt the whole climate as the amount of water actually moved by the tsunami is small as the water just oscillates up and down with propagation along the wave direction? I very much doubt that such a small global movement of water can have any effect on the global climate.

My understanding of causes of increased risk of schizophrenia was that if you had a family history you have increased chance of getting it but it also depends apon environment if it comes about. Does this mean that the brain sizes change, I dont know???? Any experts???

I am taking it as if you mean polarity of electric field. If so that the light coming from the sun has no polarity as the electric field goes it all directions. Light is only polar if you make it!

The thing is it is a long way down and pumping it out would require a lot of money and could potentially damage the building above it.

i really need to be able to get all the product and reagents out of the water table as that is going to be a lot of hydrogen chloride potentially in the nearby water system. i dont really want any product to dissolve in the water.

I am trying to build a house with a minimum amount of money as possible, as time, money, loans are short . I am currently just putting in a foundation does anybody have any smart ideas on reducing the cost of building the frame work. eg. I was going to use blocks but labour for building them and plastering makes it quite expensive. I would still like the walls to be stong and look as if blocks were put their???????????????

I have come across this problem. over the last 20 years a washing industry has been dumping its tetrachloroethane in small quantities. Recently it was discover that the tetrachloroethane haas formed a 'puddle' at the bottom of the water table below the building . There is about 10 tonnes of the stuff down a far out way. As you properly know the molecule is non-polar so that molecule doesn't dissolve in the water. We now need to remove the chemical. Does anybody have a suggestion on any way/method of flushing the chemical out and being able to collect it? HELP.

I test an experiment on Wednesday about melting ice. Would i did was put ice into a beaker and stick in it a data probe. i then added a salt eg. AlCl3. When I did this the temperature the data probe record suddenly went down by about 7degrees. However the ice melting extremely quickly. How can the salt make the temperture decrease but cause the ice to melt very quickly?