# losfomot

Senior Members

323

1. ## If Two Spaceships Close at 1.4c...?

I apologize, I do not understand your (french?) reference. Why would B need to send a laser pulse to EO? We already have janus' animation, so an extra laser pulse is redundant. The problem is that your wording is (purposely?) misleading. I don't know how I can make it any clearer than my last post.... how about this... If you want to know how fast information was truly exchanged between A and B... You will have to ask either A, or B... you cannot rely on any other observer (EO) to give you a correct answer (unless you knew you could trust that observer to have the correct formula, a good calculator, and believed in the laws of physics) edit - ahhh... trompe-l'œil... I love that type of art.
2. ## If Two Spaceships Close at 1.4c...?

Sorry, that is a presumption... not an observation. The EO observes a light signal from A 'closing' with ship B at 1.7c The EO therefore presumes (incorrectly) that A & B are exchanging info at 1.7c
3. ## If Two Spaceships Close at 1.4c...?

Yes, B and the the light from A will have a 'closing speed' of 1.7c... but this question is still different from the other statement in question: The problem with this statement is that you are mixing frames mid-sentence. "A & B exchanging info at 1.7 c" throws us into the reference frame of either A or B, where they are clearly NOT exchanging info at 1.7c... whether or not the EO is observing them.
4. ## If Two Spaceships Close at 1.4c...?

LOL.... that's funny... just gr8.
5. ## If Two Spaceships Close at 1.4c...?

Janus has explained how the EO will see it... the laser will reach B before the two ships collide... and, in fact, before a second has passed. I think your problem is still in mixing frames. You see 420,000 km between the ships, and light only goes 300,000 km/sec... so, if what Janus says is true, light must have travelled faster than 300,000km/sec in order to reach ship B in less than one second. That would only be true if ship A (or B) also measured 420,000km between themselves and the other ship. They do not. There is 420,000km between the ships in the EO's frame only. In either ship's frame the distance is not 210,000km to the collision point. Either ship will instead measure 150,000km to the collision point. Even weirder, In either ship's frame, the distance to the other ship is actually less than the distance to the collision point. (can someone else verify that I have this one right?) You can describe the scenario all the way through correctly only if you stick to one frame at a time. And each frame will describe the situation very differently... they will each measure different distances, and different times for everything that happens. And, in all of this, the only way you can get speeds exceeding c, is not by direct measurement (because nothing can exceed c), only by deduction ie: closing speeds.
6. ## If Two Spaceships Close at 1.4c...?

On a universal scale, there are many things moving away from us faster than c. Also, tachyons are hypothetical particles that may exist. But locally, when discussing physical things that we can see and interact with (like light, or particles in (or out of) an accelerator, or spaceships), all experimental evidence shows that nothing can go faster than c... therefore no information can be conveyed faster than c ... but you already knew that was the answer ... are you satisfied with the explanations to your scenario?
7. ## If Two Spaceships Close at 1.4c...?

because you are talking about what the Earth observer sees. A 'closing speed' is deduced or calculated by the Earth observer... it is not measured. However you must measure the two speeds that you use to calculate a closing speed. EO (earth observer) measures 0.7c as the speed of each spaceship... so EO can use those measured speeds to calculate a closing speed between the two (1.4c). EO cannot just assume that .99c should be added on top of that as the speed of the proton stream. If EO wants to use the speed of the proton stream in any of his calculations, EO must measure the speed of the proton stream seperately. If EO does this they will find that the speed of the proton stream is just over.99c Velocity is relative. What exactly are you asking for in this question? ie relative to which observer? In B's frame of reference, B is standing still and the proton stream is moving away from B at .99c In Earth's frame of reference, B is moving at .7c, and the proton stream is moving at just over .99c... the EO sees the proton stream moving away from B at an 'opening speed' of just under .3c Like you've stated before, closing speeds cannot be greater than 2c... the reason is that you cannot arbitrarily add speeds together like you are doing with the ships and proton stream. A 'closing speed' is calculated, but the two speeds used in such a calculation must be based on measurement. Since nothing can travel faster than c, even a 'closing speed' cannot be greater than 2c.
8. ## If Two Spaceships Close at 1.4c...?

You have made the scenario a bit too complicated to respond to all of it... but maybe this will help... The Earth observer sees two spaceships approach each other, each with a velocity of .7c, so the 'closing speed', as you've stated is 1.4c. If one of the ships, B, fires a 'proton stream' toward the other ship at .99c relative to B... what will the Earth observer see (if the Earth observer could 'see' the proton stream)? The Earth observer would see a proton stream fired toward A from B at a little over .99c... The Earth observer would see the proton stream moving away from B at just under .3c The Earth observer would see the proton stream and A moving toward each other at a 'closing speed' of just under 1.7c The Earth observer would not see the proton stream moving toward A at .7c (ship B velocity) + .99c (proton stream velocity) + .7c (ship A velocity) = 2.39c
9. ## Free Energy?

I don't understand how the medium dense gas would interact with the other gasses if it is in a separate cylinder?
10. ## Universe Expansion Diagram

It is not the horizontal aspect that I am questioning... it is the vertical. Horizontal represents time... vertical represents size (expansion).
11. ## Universe Expansion Diagram

I stole this diagram from a recent post by Spyman, although I have had the same diagram in my desktop pics for years. It seems misleading to me: This seems to be a good visual of the 'rate' of expansion, but not the expansion itself. Shouldn't the diagram be much more cone shaped to represent the expansion? Here's a link to the 'nasa site'
12. ## The Gravitational isolator

I had the understanding that the 'gravitational isolator' worked by sort of 'using up' the gravitons. In other words, because the light was deflected, it must have interacted with gravitons. because it interacted with gravitons, it must have used up those gravitons. So, if you have a disk of laser-light of sufficient density (and, apparently, frequency) it will interact with (neutralize) the gravitons to such an extent that if you put this disk between the Earth (source of gravitons) and another object, that other object will not receive as many gravitons from the Earth and will weigh less... that was how I understood it, anyway.
13. ## Questions about space, the universe and space-time

The big bang was (is) an expansion of everything everywhere. There is no specific (special) place in the universe that it happened. Whatever isn't good enough. If you were standing next to a boulder, you would say that the boulder was not moving... because it isn't... relative to you. But to someone on the moon, both you and the boulder are moving quite fast. To someone looking at you from the surface of the Sun, your moving even faster. To some alien looking at you from another galaxy, you are moving faster still. Motion is relative. You can only say something is moving relative to something else. To just say something is moving is meaningless until you define what it is moving relative to. When you say the entire universe is moving, you are comparing everything that exists to ..... what? There's nothing left to compare it to. Space is moving in the sense that is stretching / expanding... and our observable universe is only a small portion (possibly infinitely small) of the entire universe, so in that sense we do only see the same side of space... the theory is though, that space looks the same (in general) from anywhere in the universe.
14. ## The Gravitational isolator

You haven't asked for investment... you've asked for donations... these are 2 very different things. And I have to warn you that an 'invent now' patent is not an official u.s. patent and offers very little in the way of protection of your idea. Your link has two animated gifs side by side that seem to be showing evidence(?) that your idea works... if you truly believe you have made this work, then give details of the experiments you have done. The laser you are using is not very powerful. You can buy a 200mW blue laser for less than $200 This will increase your power enormously. If you don't have this much money, I have seen the laser you are using for sale at dollar stores for a buck. So spend$1 and you will have another laser and double the power. Spend \$2 and you will have triple the power. Keep us posted.
15. ## photon interaction

Is there a limit to how many photons can fit into a space.. let's say a cubic millimeter? Let's say you pointed 20 very powerful lasers so that they all crossed paths within the same cubic millimeter... would they all fit? Would it be crowded? Would they bounce of of each other, scattering at angles other than the original path of the lasers?
16. ## The Gravitational isolator

Unfortunately, the idea probably does not work. "can't work"... I wouldn't say that. It is a gamble to take out a patent on an idea that probably will not work, but it could pay off enormously one day, so if you have some extra cash... why not. If this guy had any hard evidence that it worked, then he would not need to ask for donations. Claiming this idea as a source of free energy makes the idea less credible. This guy does not even know that such an effect exists... and yet he is assuming that it will give more power back (the energy needed to turn the wheel) than it takes to make the thing work (the energy needed to power the laser). Why would he assume this? If it does work, I would guess (assume) quite the opposite... It would take an enormously powerful laser to measurably change the weight of an object.
17. ## Observable universe thought experiment

And this is kind of the gist of my question... I thought special relativity said that, from the rocket telescope frame, that distant galaxy (or whatever we are looking at) really is 7 times closer. Not 'seems', not 'compressed 7 times'... the distance is actually 1 billion ly instead of the 7 billion ly in Earth's frame (for example). I see what you are saying and it does make sense. I just thought this might be a way to take advantage of the effects of SR (one day). After watching , I don't see that the rocket-telescope would get any kind of useful image.
18. ## Picture of galaxy from when expansion only 600 million years old

I think he is measuring the distance between galaxies A and B and comparing it to the distance between galaxies C and D (the further back you go in time, the farther apart the objects are)... when he should be measuring the average distance between galaxies E and B and comparing it to the average distance between galaxies F and D. I think. The center represents Earth. lol... sorry, F and D should be closer together in the diagram.
19. ## Observable universe thought experiment

I thought the purpose of longer exposures was to capture more light from very dim objects... I didn't know this had an effect on the actual resolution of the image. These two images (photos of a photo) were taken with the same camera, but the 2nd one was from 7 times farther away. Are you saying that, if I had a long enough exposure, I could get the same quality image as the first photo? I was under the impression that the further you go to that side of the visible spectrum, the worse the resolution got (with the same size instrument)... I don't know why I have that idea.
20. ## Quick search is a little wonky

Try this: on the main page in the search box at the top, type (for example): 'neutrino photon' It comes back with the first page of 51 total topics back to the beginning of time. Now click on page 2... it has somehow broadened the search to give you 131 topics, but only for the last year?
21. ## Observable universe thought experiment

Thanks for the answers. I should have seen that myself. So our (co-moving) observable universe would actually shrink, in the direction of travel, from 46 billion ly to about 6.5 billion light years (because of length contraction). That is, the 'wall' would be in the same place, but that place would be much closer. Even if we can't see more of the universe in this fashion, it still seems to me that we would be able to get a better (clearer) picture, since we have reduced the distance 7 fold? For examples: That new furthest galaxy is roughly 30 billion light years away... but to our rocket telescope, traveling toward it at .99c, it is only ~4.3 billion light years away. (of course it was only 13.1 bly away when the light we see was emitted, so is it that distance that is reduced?.. probably... here's a less confusing example:) That new 'goldilocks' planet is 20 light years away... but to our rocket telescope, traveling toward it a .99c, it is less than 3 light years away. Being roughly 7 times closer should make for a better picture? Or is this advantage somehow nullified? Why such a hesitant answer? It seems to me that, even if our observable universe did not get bigger, the farthest stuff we can see would become much less red-shifted, and therefore easier for us to see.? Edit - perhaps this thread would fit better in the relativity subforum, rather than cosmology?
22. ## Observable universe thought experiment

We are only able to see so much of the universe. Can we alter this?... Say we built a rocket telescope and fired it directly toward a specific area of space... say the hubble deep field area. We get this rocket going about .99c and then let it coast for a day or a week... however long it takes to get a good exposure. Then we turn the rocket around and have a look at the photo... what would we see? Would we see farther than the observable universe we experience on Earth? (since distance has contracted in the direction of travel) Would red-shifting be (to some degree) reversed by our velocity toward the light we are collecting?
23. ## Expanding Universe Illusion Theory

I'm sorry DanielC, but I am going to have to call you on this one. The link you provided does not support your statement. The 'Big Freeze' is based on stars using up all their fuel, and proton decay. What you are describing is called the 'Big Rip' and is based on the possibility that the cosmological constant is not a constant at all, but is increasing over time. I am used to being humbled, so I won't feel too bad if you prove me wrong on this.
24. ## Expanding Universe Illusion Theory

I was under the impression that this is a pretty far-fetched possibility. Clusters of galaxies will probably separate... but our solar system, our galaxy, and even our galactic cluster should hold together regardless of the expansion or 'dark energy'. Is there evidence that the cosmological constant is actually increasing over time?
25. ## The expansion of universe?

There is no 'backwards' direction. The Big Bang happened here, there and everywhere... we were all in the same place, and now we are all expanding away from each other. Things are moving away from us in every direction equally... and if we were in some other galaxy (far, far away) we would see the same thing. The only way to go 'backwards' would be if everything started moving toward each other.
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