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Thanks mathematic, that's all good to know but I think you missed the point of the question. So are we saying that all the energy of the matter we can see and all the energy of the CMBR still only accounts for a small percentage of the energy required for galaxies to form the way they do?

Keep an eye out or google MK-3475 which is a drug currently being trialed by Merck. It works by chemically tagging cancer cells which causes the body's immune system to identify it as foreign and therefore attack the cell. It has, according to some published results, shown remarkable efficacy in treating multiple cancers including lung cancer even after the cancer has metastasized. Doesn't answer your question but I thought it might interest you.

I keep hearing that science cannot explain where the missing 95% of the mass of the universe is, ok so I keep hearing it in dumbed down news reports and TV shows and not so much in white papers. I will therefore conceed there is probably a large gap in my knowledge but it got me thinking. After the big bang came inflation, after inflation the universe cooled enough for matter to form which it did in almost equal ammounts of matter and anti-matter. This then anihilated almost completely leaving only a small amount of matter remaining. This must have caused another rather large bang as all that mass was in a considerably smaller universe than todays. So am I right in thinking the energy from this anihilation still has a mass equivelance and therefore a warping effect on spacetime? So is the Dark matter and dark energy we can't explain the remnants of the matter/anti-matter destruction or is it just coincidence that the 95% of the universe that anihilated seems to be the same amount as the 95% we can't now explain. seems so obvious but as I said that is based on my limited knowledge.

It's the stuff that stops everything happening all at once (Déjà vu anyone?)

IF (and its a big if) you could be absolutely stationary how fast would time pass by. The faster you go the slower time passes therefore the slower you go the faster time passes, if you were stationary would time pass infinitely quickly so is time inextricably linked to motion?

Thanks for the reply So as the radius increases the speed increases but the RPM decreases?

I'm not sure I understand a paradigm where a correct theory is contradicted by observation

Having given it some more thought what you said in you first post makes sense, I don't know, maybe it had been a long day but when I first read your post it looked wrong.

Merely pointing out that the definition you gave of time needed to decay half of amount of atoms would not only be extremely radioactive but the rate of decay would not decrease over time. I thought it was an important distinction that it is not the number of particles you start with but the number of decays you detect

I've put in bold to remind people that you are "14" and "just starting" to learn about these things Very simply if you have a counter that counts the number of radioactive decays per second and it reads say 100 decays per second and you carry on measuring until it reads 50 decays per second and it takes 2 weeks for this to happen you now know the half life is 2 weeks. If you measure for another 2 weeks your counter will read 25 decays per second and 2 weeks after that 12.5 decays per second. Half life is the ammount of time it takes something to become half as radioactive. Be careful not to be confused by what Sensei said That would be ferociously radioactive for anything with a half life of less than several billion years if that were the measure i.e 238 grammes of U238 = 6x1023 atoms, divide by a billion years = 6x1014 decays per year, divide by number of seconds per year = 19,025,875 decays per second EDIT: Also with this definition the rate of decay would be constant 100 clicks at t1, 100 clicks at t2, 100 clicks at t3, until all gone is not half life

Having a conversation the other day about the speed at which space stations are depictded to be rotating in movies and whether or not the size of the craft is taken into account. Obviously angular speed will vary depending on radius but having watched people in human sized hamster wheels I would guess that the speed needed to effect 1g would be something like 10 to 12mph just to be clear I'm thinking if the circumference was 12 miles and it rotated once every hour that would be 12mph. I can't do the maths but I would appreciate it if someone could tell me at what speed a station would have to rotate to effect 1g Thanks in advance

Obviously Thorham is struggling to understand some fundamental concepts and no-one has properly explained these, all that has come forward is the higher level results of these concepts which clearly aren't making sense to him so: Gallileo was on a ship one day sailing in a constant breeze and therefore at a constant speed, the water he was sailing on was very flat. He was in the captains quarters and looked out of the porthole and saw the outside passing by, when he turned his gaze to a candle burning nearby he noticed the smoke from the candle rose straight up. He then took a small object and dropped it to the floor noticing it fell straight down and when he rolled a ball accross the floor it went in a straight line. He surmised that travelling in a straight line at a constant speed was no different to being at rest and so the Principle of Relativity was born. In more modern language we are saying that a frame of reference that is moving in a straight line at a constant speed and one that is at rest are no different. These are called inertial frames. More succinctly put, the laws of physics in one inertial frame are no less simple than in any other inertial frame. That means the laws of physics are the same and you don't have to take account of your movement - you are stationary So you are in a plane flying in a straight line at a constant speed roughly East to West, the blinds are down and there is no turbulance. You are at rest in your frame of reference (the plane) and there is no experiment you can conduct within the plane to detect the speed you are traveling at. This is beacuse you and your apparatus are at rest in this frame. If you drop a ball it falls straight to the ground. I am on a train travelling in a straight line at a constant speed roughly North to South, the blinds are down and the track is very smooth. I am at rest within my frame of reference (the train) and there is no experiment I can conduct within the train to detect the speed I am traveling at. This is beacuse I and my apparatus are at rest in this frame. If I drop a ball it falls straight to the ground. From the outside we can measure your plane travelling at 500mph relative to the ground and my train travelling at 100mph relative to the ground but the speed of your plane relative to my train is in no way connected to the ground. If you were to magic the ground away you would be left with the speed of the plane relative to the train. I think I am stationary and you are moving and you think you are stationary and I am moving whereas we are actually both moving relative to each other. If there was a frame of reference that was not moving, i.e. absolutely at rest, then all other frames would be in absolute motion and when you drop something in your plane it would not fall straight to the ground, you would have to take into account your absolute motion. Hopefully you will now understand that to say something is not moving has no meaning. Something that is not moving in your frame of reference (i.e the ball on the plane, you put it on the table and it stays there) is moving in my frame of reference. All motion is relative, we can both be at rest in the same frame of reference or we can both be moving relative to each other (even though we think we are at rest and the other one is moving) but you cannot have the condition where one is absolutley at rest and the other is absolutely moving.

So what is a photon with no energy, does it exist? Can you detect it?

If you watch the video that elfmotat posted Feynman says at about 29mins that if you fire one electron at a time and you cover one of the slits you don't get any interference just a pile of electrons. In your post above you say "a quantum particle passed through a single slit" implying there is only one slit but this is not the case. You may aim your electron to go through one slit and one slit only but if you do not have the information that it actually went through the slit you were aiming at you will get interference. When he said N1,2 = N1+N2 this negates the possibility of interference. That's what I understood from it, I wasn't aware you can get interference from a single slit.

Thanks timo, that's starting to make more sense. So is it true to say that zero energy of a photon is a limit which can never be achieved similar to 0K is a limt of temperature which can never be achieved similar to c is a speed limit of a massive body which can never be achieved.

Bold Mine. The "I have a new theory" title to this thread was pure sarcasm, I am not under the delusion that I have altered the understanding of science. I am just struggling with the logic of some things which I know is due to my lack of knowledge/understanding. I'm aware this humble approach is rare in this forum which is a quite deliberate approach after reading some of the nonsense here. What I'm struggling with is - if when you are travelling in one direction the photon has zero energy how can it have energy again if you start travelling in the opposite direction. The photon can only have zero energy if you are travelling at the speed of light, which you cannot do, so the photon can never have zero energy answers this logical paradox. However if a photon can have zero energy then I'm back in my mental whirlpool and seeking further knowledge/understanding. Edit for grammer

The quintessential point is that if you can determine through which hole a particle travels then the sum of the particles must not contain interference, if you cannot deterimine through which hole a particle travels the sum of the particles must contain interference. I now have a much clearer understanding of this phenomenon.

Bad english, I meant something more along the lines of... moving away from the source of the light fast enough I heard somewhere that a photon with enough energy would be a black hole, a black hole travelling at c though gives one pause for thought. Wouldn't Hawking radiation evapourate it away though and would a black hole travelling at c have any gravitational influence upon its surroundings? Also, does a photon falling into a black hole add any energy to that black hole i.e. as it enters it red shifts so much it now has zero energy?

I have a new theory My theory is that I will never reach the intellectual heights of people like Newton or Einstein so all I can do is ask questions to try and understand as best I can the theories that these people intellectually superior to me come up with. So I was just wondering if there is an upper and lower limit to how much energy a photon can have. I was thinking... if you travel away from a source of light, the faster you move away the more the light appears red shifted, it has a lower frequency and a longer wave length and so less energy. It still travells at the speed of light relative to you though. So if you were to travel ever faster you would reach a point where the photon, in your frame of reference, has zero energy however you would be travelling at c, which you cannot do. This is like saying that in a frame of reference in which a photon is at rest, that photon has zero energy and so does not exist therefore a photon cannot have a frame which it is at rest with respect to. That was kind of my train of thought, if you move away from a photon fast enough it has no energy but if you slow down it has energy again. Forget the relativity part, what, if any, are the upper and lower limits of energy a photon can have?

Because there is constants

In reply to this post (I've cropped it a little bit cos there were a lot of words) I for one would rather you just provide the answer and let the discussion develop. Science is an interest of mine, not a job and as such I don't have the time or energy to devote to having a great enough understanding of the subject to allow me to decipher your somewhat criptic question. This all seems very much like another recent thread where there was a question about photons travelling side by side which "led to the conclusion there was a universal frame". I'm not saying your scientific understanding is the same just your approach in this forum is similar in that you have not really provided enough information for people to partake meaningfully. You've only provided enough information for you to keep telling people they are wrong which I'm sure you understand is frustrating. I look forward to learning something new.

It was created once though, no?

Nonsense, it's a well known fact that anything over 27mph and you explode.

So the only way for you to accept you are wrong is if it is shown another area of physics is wrong? Are you saying that the two photons are travelling at "c" relative to an absolute frame and everyone measures the speed of light to be "c" relative to this absolute frame regardless of their speed relative to the absolute frame? Or are you simply mocking people on this forum by perpetuating a ridiculus notion that if a is true b must be true with no logical reason to support it. Two photons are moving side by side therefore the Moon made of cheese!

The best definition I've heads is: Time, it's the stuff that stops everything happening all at once. You could equally ask, "what is space?", "what is energy?", "what is force?". Not sure we can answer these questions.