standardg60 wrote: » How can it not? The universe is an expansion of light, and life is dependent on that very expansion. If the universe ceases to expand, then existence ceases. It is the difference between the rates of expansion from where we are to the edge which gives rise to time.
Curious_Case wrote: » I've always assumed that the distances between galaxies is known to be increasing in all directions and the expanding universe theory is a possible explanation. As far as I know, it's the amount of red shift that provides the means of determining that galaxies are moving away from each other, nothing to do with varying speeds of light.
[Deleted User] wrote: » https://media.tenor.com/images/f0868be38014452f2dd71559bbecc402/tenor.gif
PMBC wrote: » What about tachyons?
fillup wrote: » Not in 1927 unless they'd inadvertently discovered time travel whilst measuring the speed of light but that's a different thread entirely
standardg60 wrote: » It has to be necessary. If we can see that the universe is expanding, then it must be expanding at a different speed to ours. If we were expanding at the same speed then we wouldn't see it.
Curious_Case wrote: » Simples If, for instance, the 2 cars were in a dragster race and both hurtled down the track at C (velocity of light) then they would maintain position relative to each other and neither would be moving relative to the other. Therefore they are approaching/separating at ZERO velocity but nevertheless they are, absolutely, both travelling at C. Similarly, if they are approaching each other (both travelling on the same trajectory) then they are, absolutely, closing the distance at a velocity of TWICE C. Nevertheless, neither of them are travelling at anything other than C. Velocity is defined as speed in a straight line. As the cars velocities are steady @ C, acceleration is zero in both cases.
Capt'n Midnight wrote: » But they could use a laser rangefinder.
y0ssar1an22 wrote: » a question that has puzzled me for a while... 1: car A and car B have a velocity towards each other of 100 kph. they are approaching each other is 200kph. 2: if car A and car B are doing the same, but at the speed of light why are they not approaching each other at (2)(speed of light)? if the rules of physics hold for scenario 1, why not scarios 2? is there a simple explanation here? i dunno, maybe we just don't have an answer?
Gregor Samsa wrote: » There’s an interesting phenomenon called time dilation that happens the faster you travel. It’s not something you can notice at human speeds (unless you’re measuring with an incredibly accurate atomic clock), but the faster you go, the slower time goes relative to observers travelling slower than you. If you go at 90% of the speed of light, your perception and experience of time is half of a static observer. You’ll actually age half as slow as them. If you travel at the speed of light, for you, time stops, and you’re therefore bot able to observe anything in the universe. Basically at that speed, for you, nothing else exists except yourself, and time is infinite. If you have any mass, your mass will also become infinite at the speed of light. It would therefore take an infinite amount of energy to get you there. Your length also reduces in the axis you’re travelling the faster you go. And again, the effect is infinite at the SOL. So, if you were a solid object of any size, it would take infinite energy to get you to the speed of light, and once you got there, you’d have infinite mass, zero length, time would stop and to you the universe would cease to exist. This clearly means that it’s impossible for anything with mass to travel at the speed of light. It also shows that nothing can travel faster than light (it would take more than infinite energy to do it, which can’t exist, and you’d end up more than infinitely massive and less than zero in length - again, things that just can’t happen) Fortunately, photons and other particles that do travel at that speed don’t have any mass, so they don’t have to worry about the physical effects.
Deleted User wrote: » No. If I am walking at a particular constant speed, it does not mean the car next to me is moving at a constant speed. They are not related to each other. The speed of the expansion of the universe is different at different distances from us, but that has nothing to do with the speed of light.
standardg60 wrote: » If the universe is expanding at a speed greater than the speed of light is that not confirmation that it is not constant?
Deleted User wrote: » I think you are getting a bit confused between the speed of light and the speed of the expansion of the universe. They are not the same thing, but that does not suggest that the speed of light is not constant. The speed of the expansion of the universe is instead determined by the Hubble constant (~68km/s per megaparsec). As for your last sentence, the outer parts of the universe (beyond the Hubble radius) are actually receding at a speed greater than the speed of light. Therefore, any light emitted outside of this radius can never and will never be detected by us.
standardg60 wrote: » This is the most rational explanation of what is life that i can conjure up in my own head. The universe is an infinite number of carriages that leaves a train station at an infinite speed. Immediately one carriage is unhooked after another and is left to drift under it's own initial energy. Each carriage will eventually pass through a point in time occupied by the train, it is this interval that is existence, an experience or phenomenon that exists between two speeds of light. But no two carriages will ever meet again, each will stop at a particular point along the track, and when they stop existence will cease. It is only their movement relative to the train which creates time. Is there therefore something that transfers from the last carriage to the second last that leads to the progress of mankind? Is that what procreation is? A transfer of something which is resistant to time.
fillup wrote: » They had to cover rough terrain to measure the distance between their measuring apparatus- they couldn't run a 35km measuring tape between the two sites.
Deleted User wrote: » I don't see why you think it is necessary for the the speed of light to vary in order for things to change. As long as light has a speed, constant or otherwise, then information can be transferred and therefore things in turn change.
[Deleted User] wrote: » This is the paper about their measuring technique. If you still don't understand something about the method after reading it let me know.
blinding wrote: » Why would they measure over the rough terrain ? Light goes directly except in exceptional circumstances !
fillup wrote: » Slightly off topic but seems like I might get an answer here from one of the Boardsie Boffins... Out of curiosity I was googling how Michelson measured the speed of light back in 1927 As explained in this video, they shone a beam of light between two mountains and timed how long it took for the light to complete a round trip between the 2 points. At around the 5min 30 sec mark the lecturer explains how they measured the distance between the two mountain tops to within 8 cms despite them being over 35km apart They used triangulation and a 50m measure to to calculate the distance but I still can't figure out how they calculated the distance over the rough terrain between the 2 peaks Anybody care to explain? Tnks Link to video -https://youtu.be/I_RG7R15eCM
standardg60 wrote: » What i like to ask myself is what is causing our sense of the passage of time. What makes the past the past and the future the future.If the speed of light is a constant and always has been throughout the universe, then why does anything change. We see change because we can see things which happen at a different relative speed to us. Could this not be the case on a universal scale? That different areas of the entire universe are all moving at different speeds of light, therefore causing a difference in time. Someone posted early in the thread a link that posited that indeed there may be light speeds at the edge of the universe that could be many times c but that we don't need to question that as it's not relevant to us. But what if it is that question that is the meaning of life? That that is the reason why our time passes. It's all relative!
Deleted User wrote: » We know by analysing the data from the Oklo natural reactor that the speed of light has not changed in 1.7 billions years, so it certainly did not change last week.https://www.forbes.com/sites/startswithabang/2018/10/04/earths-first-nuclear-reactor-is-1-7-billion-years-old-and-was-made-naturally/
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