Hoppy

Carl, I'm not surprised people get upset when you adopt such an aggressive tone, especially when I have speciically stated that I am not dissing Numbus for his interest and have also praised academic endeavour as worthy in its own right.

Nimbus has done his best to explain some pretty alien concepts to your average bloke, ie me, and I'm grateful.

Now I understandand what polarising filter is and how it works in a worldly photographic context. Please explain more about what you can do with three of them as it's something I might just grasp. This will benefit me and also enhance your cause

Thanks,

Richard.

Nimbus

SuperString theory in a nutshell (this is from memory so some of the details may not be accurate..

All matter is made of atoms. These are in turn made up of Protons (positive charge) and neutrons (no charge) in a nucleus, surrounded by orbiting electrons (negative charge). The "mix" of these three particles gives different elements. It was found some time ago that each of these particles is in fact made up of one of two types of quarks (called the UP and DOWN quarks). There are also other types of quarks that have been discovered using particle accelerators, which smash protons together at very high speed to recreate conditions during the early stages of the universe). It is theorised in that the different types of quarks are actually made up of tiny (planck scale) "strings" of vibrating energy. Later theories speculated that these strings actually move about in not only our own 3 dimensions, but also in curled up extra dimensions at the planck scale.

I can not really give you too much more than this as it's a while since I last read up on it. It you are interested in this there are many books available which can explain it far better than myself. They are well worth the read.

In a word, yes.

What caused the big bang is something that we may never know. There are lot's of theories but I don't know what the current thinking is. I'll have to look that one up..

There may not be a big crunch. It looks like there is not enough matter in the universe to halt the expansion.

Conditions as the beginning of the universe are difficult to determine due to the high pressures and temperatures involved and the thories necessary to understand it. We understand what it was like close to the beginning (10-43 seconds. That's zero point (43 zeros later) 1 seconds after the bang). At this point in time the universe was about the size of the planck scale (remember this is the size of a tree, if an atom was the size of the current universe). Atoms did not form until after 10,000 years had passed

Right, time for my coffee...

Leslie

Fascinating stuff I must say. I still keep wondering what was there in the first place for the universe to form from. It seems amazing to me when you consider all the matter there is in the universe. Is it considered possible for pure energy to be converted into matter? Basically what could have been in existence before the bang? Was there even an earlier universe?

Les.

Nimbus

Yes. Since matter and energy can be converted from one to the other. This is the heart of the famous E=mc2 equation. Energy (E) = mass (m) x speed of light (c) squared (2). Since the speed of light is a very large number you can see that the amount of energy within matter is very large. During the very early moments of the big bang, there was only energy at tremendous pressure and temperature. The components to make matter, so to speak, the quarks, protons, neutrons, electron, had not formed. In fact, the forces that enable the to form had not even been created (electromagnetic, the strong and week nuclear force). It's only after the universe had cooled that the forces came into being (or more accurately split from a "grand unified force") and strings were formed from this energy, which created the quarks, which created the protons, neutrons, electrons, which created atoms. How the strings were created I don't know. Like I said it's been a while since I read up on this so may be a bit of a refresh is in order.

Leslie

Thanks for that Nimbus. I have never thought about it like that and it seems to be getting more interesting as I think about it. I can see a logical order in what you say of course. When you consider the make up of all matter with all the different elements and the substances which formed from them and their interelationship in the Universe, it seems almost impossible for the mind to encompass it all.

I wonder if man will ever to be able to go back before the big bang and to know just how all that energy coalesced in the first place.

I also wonder sometimes if the laws on nature as we know them could be changed in far flung parts on the universe.

Les

Nimbus

This is the search for the "Theory of Everything". It's not so much that the laws of physics can be different in different locations (or times) in the universe, it's that we need to develop a theory that encompass them without demolishing what we know already.

Consider this example.. Ancient man sitting on earth. He throws a rock and watches it fall. He can determine that with a particular strength of throw it will travel a certain distance. If he were to be transported to a planet with a higher mass, he would throw his stone in the same way, but this time it does not travel the same distance. It falls short. He scratches his head in wonderment. Have the laws of physics changed he asks? Of course not. It's just that he is on a more massive planet. He does not understand that this means the downward pull on the stone has increased. His "universe" may be behaving differently, but both worlds are following the same law of gravity.

It's the same now. With places like black holes and the early moment of the big bang. The laws of known physics may not be able to help us, but that only means we haven't fully worked them out yet, not that they are different. As well as large scale events, we also need to factor in physics on the microscopic level (the Quantum Mechanical level). Trying to work out a single theory that works for both these levels is the current challenge.

Leslie

Good explanation . I can see your point exactly how things may appear to be obeying different laws when placed in a different environment. I found it interesting when they showed that programme recently about trying to reach absolute zero temperature. They mentioned that liquified gases at those sorts of temperatures liked to flow uphill! It all comes down to what we are used to seeing in our normal environment and what can happen in a totally different one of course. Another fascinating point is that they say when you travel at very high speeds, time seems to alter in its relationship so that when you return to the origin of your journey you are a little younger then when you started it. Can you see a real time machine in there somewhere?

Les

paul-s

an intergalactic scooby meet would be good !

Nimbus

This is time dilation. It's not that you would return younger, but that you would not have aged as much as someone who was left behind. It's been proven that at very high speeds time actually runs slower than for stationary objects.

Maz

iTrader: (34)

The difference is very marginal though. Now bearing in mind mass and energy are interchangeable would it be correct to assume something as innocuous as say a piece of paper, has enough energy to run a house. Would it be possible to release that energy or is it not viable with such materials? Are nuclear fuels used because they are already very unstable and easy to extract energy from?

Leslie

Yes I realise the distinction and that is effectively what I meant and did not put it very well. To become younger would not be right at all. But still a bit of a marvel to not be as old as you might have been after the journey.

If they ever manage to go faster than light, it might become more significant!

Les

Nimbus

It depends on your speed. The faster you travel the slower the clock will run. At 80% of light speed for example, the clock would run at approx 1/2 the speed of a stationary one.


Providing you had a away of converting all the matter in a piece of paper, you could probably power much more that your house. I think the only way of doing this though is with anti-matter.


Yes, I believe so.


As you travel faster your mass also increases. So it takes more energy to accelerate. As you reach the speed of light, your mass increases to infinity, so it would take in infinite amount of energy to accelerate any further. Because of this effect, you will never be able to travel faster than light.

Maz

iTrader: (34)

What actually propels light?

Leslie

Unfair question

Energy!

Les

Nimbus

Nothing "propels" light. Light is one part of the electromagnetic radiation spectrum (which ranges from Radio at one end (long wavelength) through to X-Rays at the other end (short wavelength)). The electromagnetic force is one of the four fundamental forces of the universe. The others being the Strong Nuclear (holds protons together in the atomic nucleus), Weak Nuclear (responsible for radio active decay) and Gravity (sticks you to your chair). The photon, which "transmits" this force is mass-less. It can only travel at the speed of light. No slower and no faster.

Nimbus

Put it another way. Einstein (Albert ) proposed that everything in the universe can be said to be travelling at the speed of light in space-time. By this, it is meant that as well as the three spacial dimensions we need to include time. People, car, aeroplanes travel only very slowly through the "Space" direction, but very quickly through the "Time" direction. As you travel faster in the "space" direction, your speed through the "time" direction reduces. This is what's happening with time-dilation. As you reach the speed of light, your speed in the "time" direction has reached zero, but your speed in the "space" direction has reached the speed of light. With this idea, it can be said that everyday objects (and most of the univers) have what is called a "timelike" existance, while the photon has a "spacelike" existence.

Geezer

Doesn't the photon sometimes display properties of a particle? And, if it's massless, how come it is affected by gravity?

I'm sure I read something about all things are massless, except the Higgs Boson goves it mass (as yet undetermined)?

Also, hasn't quantum tunnelling been 'proved' go faster then light?

Geezer

Nimbus

mmmm.. I knew I should have stopped posting on this thread... You're getting me in to Quantum ElectroDynamics now..

The whole "is it a wave, is it a particle" question has been going on for some time. The answer is that it's both. Sometime light displays wave type properties (and produce interference patterns) , other times particle like properties (when dealing with individual photons). It's the photon that is the "messenger" particle for the wave information... If that makes sense..

Because gravity warps the fabric of spacetime. The path of the beam of light is not being "pulled" by gravity, it's simply following the warped path of space itself that is created by gravity.


Well, I'd have to look that one up. I don't think that's correct, since I recall that Bosons are part of the force carrier particles. Saying that though, the weak gauge boson (which transmits the weak nuclear force) does have mass, so you may be right in there somewhere. I'm just not sure it's the Higgs.

Not really. I'm not that familiar with Quantum Tunnelling, but what I understand is this. You can never say with with exactness the location or velocity of a particle. You can only give a probability that a particle is in a perticular place at any one time (this is part of the Uncertainty Principle and is the particles "probability wave function"). If the particle is fired at a barrier, the probably wave function that make up this particle can spill over the barrier onto the other side. So there is a small (but not zero) possibility that the particle will be on the other side of the barrier. The particle is said to have "tunnelled" through the barrier.

The energy that the particle needs to "tunnel" through the barrier is "borrowed", but as long as it is paid back in a short enough time and the overall energy dept is zero, the tunnelling can take place.

Geezer

Thanks for the reply Nimbus

Geezer

Maz

iTrader: (34)

Yikes my head is spinning! Would this theory purport that light is not bound by the the same physical laws as all other matter? Are time and space bound together with a hitherto unknown connection? Also how is it possible for gravity to warp space itself if there is nothing physical i.e something with mass to be warped? Also it is said not even light can escape a black hole, why? Finallly these supermassive black holes in the universe, how much mass is contained within them and can they feasibly swallow a galaxy (not the choclate)?

Leslie

I imagine then that when I stated "energy" as the propelling force for light, what I should have said was that the energy content of the light source dictates the brightness of the light beam by emiitting more photons into the beam?

There is many a trap in all these definitions etc. but most interesting.

I was interested to see that the behaviour of light either as particles or as waves has still not been resolved after all that time since I was taught Physics.

I must say though, unless I remember it wrongly, that it was stated that light beams can be bent by gravity and that this is exhibited during astronomical observations.

Les

Nimbus

Not sure what you mean. Matter and light are different (they are after all made form different particles), they do behave differently, but there are laws with govern how they each behave.

Space and time are connected. This is what Einstein referred to as "spacetime". You can not develop theories or experiments for one without factoring the other.

Maybe I was not clear. I didn't mean that spacetime can warp by itself. The fabric of spacetime is warped by the mass of an object. This warping is what we refer to as gravity. You can not warp spacetime without the mass being there.

The mass of a black hole is so great and the pull of it's gravity is huge that the escape velocity is greater than the speed of light. It basically means that it's escape velocity is so great, that light itself is not going fast enough to escape. Or put it another way, the warping of spacetime is so steep that light can not craw out.

I had to do a bit of searching for the sizes. Supermassive black holes range from hundreds of thousands to tens of billions of solar mass (ie, the mass of the sun). Many galaxies have been found to contain one at their centre. It's feasible for a supermassive black hole to consume an entire galaxy (since the more they consume, the larger they get and the stronger their gravitational pull) but it would mean that the stars and other matter of the galaxy would need to be deflected from their current stable orbits and deflected into the centre. Even then, they may just pass the black hole and be ejected from the galaxy, rather than end up in the black hole itself.

Nimbus

I think it's more that the energy of the photos dictate the light frequency (and hence colour) but the number of photons dictate the brightness.

I think the current thinking is that it has been resolved, in that it is both wave and particle, depending on how you use it.

Correct. This is the spacetime warping I mentioned. This have been proven by observation. The first time was when their was a solar eclipse (can't remember the year) when the apparent position of stars that were on the very edge of the solar disk (which was obscured by the moon of course) were seen to be moved by precisely the amount Einstein predicted.

PeteBrant

Worth pointing out at this point, that the physical laws that govern the Macro universe and the micro universe are quite often turned on thier head