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Since light has constant speed, when you turn a light bulb on, how does the photon generated reach the speed of light without acceleration?By SciTechPress
How would you answer this question?
Let me attempt to blow your mind: “Now” travels at the speed of light.
When the light turns green, I don't concern myself with the fact that the light actually turned green a nanosecond earlier than I saw it. As far as the distances we're used to, “now” might just as well be universal.
On interstellar distances, you might expect that the lag start mattering. Except it really doesn't. Maybe Sirius isn't there anymore. Maybe it went supernova five years ago, and the shockwave is riding towards us as you read, and it will hit us in another three years. There's no way we'd know. We look up and see the old faithful Sirius sitting right where it's always been. And we can measure its gravitational influence on us and neighboring stars. There is no knowing it's actually gone, and that's because it actually isn't. To someone in the neighborhood of Sirius, the star is no more, but, to us, it still exist. “Existence” travels at the speed of light.
If the sun was spirited away by a species of prankster kardashev 3 aliens, it would keep “being there” for 8 minutes as far as we'd be concerned.
And those 10 billion light years away stars we see through our telescopes, they are there. Because we can see them.
- Julien Boyer
By Bible Speaks
Origin of the Universe:
Gen. 1:1: “In the beginning God created the heavens and the earth.”
Astronomer Robert Jastrow wrote: “Now we see how the astronomical evidence leads to a biblical view of the origin of the world. The details differ, but the essential elements in the astronomical and biblical accounts of Genesis are the same: the chain of events leading to man commenced suddenly and sharply at a definite moment in time, in a flash of light and energy.”—God and the Astronomers (New York, 1978), p. 14.
When you turn a light on, does the light instantly travel at the speed of light (186,000 miles a second), or does it start at 0 and increase its speed until it reaches its top speed?By SciTechPress
Light always travels at the speed of light. It never increases or decreases its speed. (Technically, this is only true when the light is in vacuum, but the air in a room where the light is turned on is sufficiently close to a vacuum.)
You're thinking about light as a classical particle, which indeed has to start from rest if it wants to move. Instead, think of light as a vibration of the electromagnetic field.
There is a simple analogy for this - without any quantum mechanics or relativity, just classical mechanics.
Consider a string attached to a wall on one side and held by you on the other side. If you vibrate the string on your side, the vibration will propagate to the other side at a fixed speed that depends on the material from which the string is made and on the tension of the string.
The propagation speed of the vibration of the string does not start from zero, nor does it increase or decrease at any time. It is always constant.
Similarly, light is a "vibration" of the electromagnetic field. This vibration always propagates at a constant speed c.
- Barak Shoshany, Graduate Student at Perimeter Institute for Theoretical Physics
Listen to my commentary on this
"The notion of mass "increasing" with velocity is an outdated one. Under current definitions of "mass", mass doesn't increase at all with velocity; instead, it is an intrinsic property of the object in question, which is the same in all reference frames.
... If you're inside your rocket ship traveling at 99.99% of the speed of light relative to Earth, you wouldn't be able to tell you were moving at all without looking out the windows (or at your instruments, etc.) Specifically, you would not somehow have more trouble moving because of your increased inertia, and you would not see time slow down for yourself. It's only observers on Earth who would see your time slow down and your inertia increase."
The magnitudes of most of the famous effects of special relativity (time dilation, length contraction, increase in inertia) are determined by the "gamma factor",
This is where Allan Steinhardt's answer comes from. It's the factor by which inertia increases, and it's the factor by which we used to say your mass increased, before "mass" was redefined. (Again, this is all according to an observer who sees you moving at 99.99% of the speed of light relative to them; according to you, everything about you is "normal".)" Source
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