michel123456

Dear professor thank you for taking time answering these questions, it is simply invaluable. [Here takes place the presentation of "who is talking"-- dear Mods what do we do here?-- for example; Michel, 52, Architect, from Belgium & Greece] From one of your interviews over the Net i picked this little excerpt So as it seems our common understanding of cosmology has created a model that predicts that future observers will be unable to understand the Universe the way we do today. Here comes the question: The cosmological principle sates in some way that all observers are equal players in a fair game with the same rules over space. From your quote it looks like over time, in the far future, the game will become unfair for some observer because this observer will not be able to observe the remnants of the Big Bang. Does that mean that Nature does not play fair ? and that the cosmological principle cannot apply for objects in the far future and thus cannot apply for objects in the distant past and as a matter of consequence cannot apply for distant objects? -------------- (edit) Or, to put it another way: doesn't this conclusion in your quote rings a bell to you? Can't we imagine another model of Nature where there are no lucky observers like us but a model where all beings over time are equally "lucky" to observe the same universe as we do ? Thank you.

You are completely wrong: it is Moon-Tan-Man.

He says that there is no absolute 'tick". If the rate of the "tick" changes universally, nobody would notice anything. ------------------ And what i say is that if the "tick" changes universally (yes) but not everywhere "at the same instant" then we would notice the change.

If time changed instantly, yes we couldn't measure it. But if time changed over distance, we could. It would appear as the diagram below from Ned Wright's tutorial "If we now "stretch" the time axis near the Big Bang we get the following space-time diagram which has straight line past lightcones:"

So far we (you) have achieved mach25 for a 100 tonnes object. That is 8200 m/s to be compared to the estimated 15000 m/s atmospheric entry of the russian meteor.

I didn't read thoroughly the whole thread but I have something to say about E=mc^2 The = sign is language. The meaning of "equal" you cannot put in mathematics because that would be circular reasoning. I think. For example in E=mc^2 one could say that the = sign does not mean properly "equal" but means "equivalent". Both meanings are language.

If you make physical constants vary, these are not "constants" anymore. By changing the constants you obtain other "physical" effects that may or may not correspond to datas. But that's always about "constants" as factors in existing equations. for example the value of C may be considered different and produce different result but the equation E=mC^2 is not under question. When one states that "the laws of physics could be different" that would be for example E=mC or E=mC^3 or wathever. Which is not what happens as much as I know.

the object is not made of fuel. It is not a flaming aircraft. It is a rock. it can burn like lava but the main thing that is burning is the atmosphere. When a spacecraft enters the atmosphere, what is burning in front of the protection shield?

Thanks, you are fast. So the difference is between a (russian) object of roughly 2 meters diameter and a (american) object of roughly 20 metres diameter. A falling SUV against a falling 6 floor building, both full of concrete.

This so far from the guardian Digging in progress

Basically the russian (?) number is spread over by the greek media here. I'll have to check out.

Thank you Moontanman, at last some info. Great post! Under "light & sound effects during flight" (P53) - read it on the link (Ididn't want to break the copyright by posting the excerpt here) No mention about the Flash although. As I mentioned above, Russian source estimates the weight as 10 tonnes, not 10,000 tons see post #45 . The discrepancy is of 10^3 order. the wiki article is kept up-to-date constantly.

And why the samples found on the ice lake did not melt the ice? Where they cold when reaching the ground?

As Captain said we are all going to die but not all together at the same time which is what frightens people. That's another topic indeed. And that is not related with the asteroid. As pointed above injuries were caused by curiosity and buildings. And lack of information on what to do when a flash occurs. On the last picture one can observe the fumes make a spiral. As if the asteroid was rotating upon itself, like a spinning bullet from a rifle. The straight path indicates the same. (or maybe - I don't see clearly- maybe it is a double spiral rotating clockwise & counter clockwise. The double fume is intriguing anyway.

Informations diverge: 10 tonnes from the ones (that is ten thousands kilograms) 10,000 tons (I suppose meaning short tons) from the others = approx 9,072 tonnes (that is nine millions kilograms) That's a difference of 10^3 ------------------ From the very little info I can get it seems to me the most probable explanation is that the ionized gases of atmosphere exploded, producing a little sun for 5 seconds. This above a rotaded image of the trace in the russian sky. (original image from wiki here)

Kaboom say yes. Ka-flash I don't know why. When a pressure cooker explodes, there is no light.

You made your own explanation, does that mean that you too feel a lack of information? i can accept any explanation for the explosion but i need something that explains the flash. The light was so bright that it produced shadows (IOW it was brighter than the sun). You don't get such an effect with a simple fire.

Scarce information Plasma. --------------- Edit: exploding plasma?

Cool optical illusions

----------------------- Found this about Barringer Meteorite Crater in Arizona: From here (emphasizing mine) -------------------- And the "does not work mobile" from the OP is also interrogating.

The law of conservation of energy should tell us that the universe cannot procreate, In the sense that the universe has no external source to borrow energy from, grow and reproduce itself. Unless of course there is some external source "out of the universe", that is not encompassed into the universe itself. That is for the universe as a whole. But it is an evidence that elements of the universe (human beings for example) can reproduce. So, at the moment we consider ourselves as part of the universe, yes the universe is alive, like an inhabited house is alive and an abandonned house is dead. now, if you are asking wether other parts of the universe are alive, stars & galaxies for example, it depends on the definition of "life". It is sure that without the Sun we all would be dead, so if one wants to include the Sun into the biosphere, why not.

Found this below from here . Not very convincing. All this looks like coming from "common sense". i see no scientific explanation. When one reads from wiki: To me that is not an explosion caused by thermal (chemical) reaction. More like a hydrogen bomb.

Something occurs when it is possible to occur. Say you have a phenomena that has a unique possibility 1 into billions and billions to happen. In human understanding it is a phenomena that is very unlikely to happen. Although given enough time & space, it will happen unavoidably.

But heat comes from the outside and the meteorite is supposed to be solid rock. It is not full of kerozene.

I don't explain the concept clealy i am afraid. take a random point A in space. From point A you can look at Alpha Centauri: it means that at least one photon from Alpha Centauri reached point A. From the same point A you can look at Galaxy NGC1365: it means that at least one photon from NGC1365 reached point A. and you can continue From the same point A you can look at Galaxy NGC6872: it means that at least one photon from NGC6872 reached point A. All those photon overlap each other. And continue this way with all the galaxies of the observable universe. All these are sending at least one photon to point A. That makes a lot of photons simultanately at point A. Billions and billions.