A question about the speed of light and black holes

I'm not sure if this should be in the science board or space so mods please move if misplaced.

SO.. I'm certainly no astrophysicist but!.. I was just thinking about E=mc^2 and black holes and so forth and I was hoping someone a bit more educated on the subject could help me understand something.

If the closer something with mass travels to the speed of light, the more mass it gains than instead of just not being able to reach the speed of light wouldn't it get to the point where there is just so much mass that the object collapses in on itself and creates a black hole? The more massive an object the stronger its gravity right?

Nothing can go faster than the speed of light, aka the universal speed limit or whatever, but if light can't even escape a black hole it just makes sense to me that once you pass the speed of light you go to something with infinite or at least incalculable mass, or a black hole.

So, obviously I'm wrong but I don't understand why gravity isn't considered the "fastest" thing in the universe if it can even suck in light.



On a side note that would be cool if black holes exited at white holes and it just took traveling past the speed of light in order to "warp" across vast distances. eh eh?

Originally posted by xxblackoctoberxx
... I don't understand why gravity isn't considered the "fastest" thing in the universe if it can even suck in light

The standard explanation is that light is matter (photons) and gravity is a force. Force does have speed of propagation as well ... here's something on the subject: metaresearch.org...

Btw, 'force' is a standard scientific euphemism for 'I gots no clue how this works' ...

reply to post by xxblackoctoberxx


The relativistic mass an object gains by approaching the speed of light will in no way add to its tendency to form a black hole. The increase in mass exists only in a reference frame that is not co-moving with the moving object (essentially, one that's at rest). According to the object, it has not gained mass. Therefore, it will not have formed a black hole. If it hasn't formed a black hole in one reference frame, then it hasn't formed a black hole in any reference frame (given the constancy of the speed of light).

This is explained by the fact that the measured increase in mass of the object is not an actual increase in mass. It's the measured result of the addition of kinetic energy to the object, which, according to mass-energy equivalence, can appear to be the same as mass under relativistic conditions.

reply to post by CLPrime


ohhh ok, that explains alot. im trying to learn more on the subject and nothing ive read or watched has put it that way but yeah, i suppose that pretty much gets rid of that idea

well that was easy. thank you!

reply to post by xxblackoctoberxx

when you said "Nothing can go faster than the speed of light, aka the universal speed limit or whatever," time can travel faster than the speed of light it takes 8 minutes for the sun light to reach the earth and sunlight goes the speed of light

The term light speed can at times be misleading . We know that light can be slowed down .

reply to post by sakoy


Actually space time , as per the theory , does move at the speed of light . The theory goes , if the sun were to disappear right now , we would not feel the gravitational change for 8 min . It would take the space time distortion 8 min to reach us , so they say

reply to post by Max_TO


No, it can't. Light must always travel at 299,792,458 m/s. If it doesn't, it's unable to self-propagate and the EM wave collapses.
What we call "slowing light down" actually involve passing it through a medium in which, essentially, the absorption and re-emission of that light is significantly reduced. Light always travels at the same speed.

reply to post by CLPrime


You may be right , I simply do not know enough about it to disagree . Having said that there is a fair amount of info out there that makes the claim that light speed is not a constant .

Thanks for pointing that out though

reply to post by Max_TO


I actually just got done posting about this in another thread. There are certainly theories that suggest a variable speed of light, but such theories ignore the consequences of two of Maxwell's equations, which, together, require a constant speed of light.
The proof of this I just posted is here.

It's funny to me that when talking about the speed of light people always seem to leave out relativity. As was said, mass attracts mass. Therefore the bigger the mass the stronger the gravity. From our perspective the speed of light can only be mathematically calculated, we do not have the technology to actually observe this speed. It's kind of like the bible, we just have to have faith in the math until we have the technology to prove or disprove it.

Light speed is variable, whenmoving toward a massive body it can speed up, depending on the size of the body, its basically the same concept as when a planet begins to speed up as it gets closer to a star, then when its shot away by the stars gravity, after it passes the star, it begins to loose speed. So, theoretically speaking, outside of a galaxy light speed is slowed down by its galaxy of origin until it begins to be pulled toward the next more than its "birthplace". At this point it begins to speed up again until it passes the outermost star. Then it begins to slow down again. Just because the math seems correct doesn't mean that it is. It's just all we have to go on at this point. Light speed is definitely variable but its differences are currently immeasurable.

reply to post by DarkSarcasm

Light speed is variable, whenmoving toward a massive body it can speed up ...

You can't use this analogy. Light is not a particle in the classical sense, it has no rest mass.The kinetic energy of a photon E = h * f is independent of its velocity. It won't be accelerated in a gravitational potential. In fact it will experience a frequency shift(blue shift while moving towards a mass and red shift while moving away) but its velocity will remain constant.

Complicated stuff isn't it? I just read something recently that shocked me about the speed of light. It moves past us at a rate of about 671 million miles per hour. But if you could get to speeds of maybe even half of that, you'd expect the speed of light around you to be cut in half also, because you're kind of catching up with it. Not true apparently. The light is still passing you at 671 million mps.

A simpler way to look at the puzzle. If you're being chased by a car that's doing 70mph and you try to escape on a bike at 30mph, the car is moving 40mph faster than you. But with light speed, no matter how fast you're going, the light is always 671 million mph faster than you. That's weird.


So that's true, or, the book I read was too much for my wee brain and I read it all wrong.

You have to throw time into the equation. Everything is subject to the progression of change. The faster something moves the more it will change until it becomes pure energy. Once that happens, the effects of gravity will take over so that as light, it can be affected by bodies if mass below the light speed limit.

Since a black hole is the ultimate gravity well. It will of course pull energy into it. But a black hole is not energy, it is a gravity well, or a point of intense gravity caused by the inversion of stationary matter. Energy flows into because it is easily effected by the gravity.

If you get too close to a black hole you will be pulled inside and crushed. Gravity did this. It's as simple as that. So it doesn't matter if you're pure energy or stationary mass, it's the gravity that will get you in the end.

reply to post by DarkSarcasm


As moebius explained, light is not accelerated by a gravitational potential. I don't know how many times I have to say this, but under no circumstances does the speed of light change. Due to the constraints of Maxwell's equations, it simply can't happen.

What I really wanted to reply to, though, was the idea that we can't directly the measure the speed of light - that it's too fast for us to measure. In fact, we measure the speed of light directly all the time. We bounce a laser off a reflector put on the moon by the Apollo astronauts and time how long it takes to return. Twice the distance between the Earth and the Moon divided by that time is the speed of light. And, if you don't consider that a "direct" measurement, then no speed we measure is ever done directly. How do we measure the speed of a turtle? We measure how far it goes and divide that distance by the time it takes to go that far.

Even the first measurement of the speed of light we ever made was a direct measurement. Not quite as direct as the above, but there's nothing strictly mathematical about it. Back in the day, Ole Roemer noticed that Jupiter's moon Io seemed to orbit differently at different times. Specifically, he noticed that, when the Earth was closest to Jupiter, Io seemed to be ahead of where it was calculated to be. When the Earth was farthest from Jupiter, Io seemed to be behind where it was calculated to be. Roemer concluded that this was due to light traveling at a finite speed. Roemer measured the differences in Io's orbit at different times and recorded the distance of the Earth from Jupiter at those times, and, from that data, Christiaan Huygens was able to calculate the speed of light to be around 213,000 km/s. The accuracy of this, of course, has since been greatly improved.

reply to post by xxblackoctoberxx


Well just because it's force can suck in light, doesn't mean it itself is going faster than light. Also you have to remember gravity isn't IN space-time, gravity IS bent space-time. And the speed of light is only the speed limit in space-time, not of space-time.

Remember if inflation happened, then space-time expanded much faster than light at one point. If space-time itself is outside of space-time there should be no limit as to how fast it can "move." It defines what motion is in the first place.

reply to post by CLPrime


Very cool , thanks for that link and the correction

What do u think of this, i found it in comments on some article about time travel, but guy who made this comment really made me wonder about universe and reality: (i posted this on 2 other topics here, which are related to this subject)

You can't go faster than the speed of light because the speed of light is not a «speed», it is a «refresh rate». Matter is Energy and Energy is intermittent. There, not there. The refresh rate of matter is the speed of light. Imagine a clip on youtube, whether the apparent movement is fast or slow, pixels are refreshed at 72Hz (or so). Matter doesn't actually move, it appears at one pleace and reappears at a slightly different place giving the illusion that is has moved, but in reality each piece of matter teleports itself from one place to another all the time. You don't need a College degree to understand that. So time travel doesn't happen when the energy is present, it happens when the energy/matter is absent. Beyond space, beyond time, in the realm of forms. Imagine a perfect sphere, while your're in the office. Then imagine it again when you are at home. The perfect sphere form was not affected at all by your displacement in time or space. Because it exists in a different realm. In fact the perfect sphere form would still exist if the universe didn't exit, if the Big Bang had never happened. The same way as the human conscious mind goes back to the inconscious and collective mind thousands of times per second to try and make sense of it all, the individual particle goes back to the primal goo 4 to seven times per attosecond to refill the energy. What we perceive is the expression of a meaning. General semantics warned against mixing an object with its name. The expression is not the meaning, but if you study the medium long enough, you eventually get the message.

Sound very interesting. Just imagen if all of that could be a reality now. It would change our world.

"If the closer something with mass travels to the speed of light, the more mass it gains "

density does not equal mass
a black hole can have the mass of a teacup

and be more dence,

than Jupiter.

density does not equal mass
mass does not equall density.

"If the closer something with mass travels to the speed of light, the less mass, but greater density,,

too the point of a black hole,,where, light, which has no mass,
is curved by,, X ,,,
to the centre of said ,, black hole.

at least thats how i see it.