# If going faster than light requires infinite energy?

And black holes have infinite gravitational energy, why couldn’t one bigger black hole remove something from another black hole? Couldn’t they just go back in time like a tachyon?

Update:

Light speed requires infinite energy.

E=γmc²

E=(1/√(1-(v/c)²))mc²

If v is c, solving for m, it can be shown that at light speed, your mass is infinite. According to ΣFΔscosθ=Δ[(1/2)mv²], infinite mass means infinite kinetic energy and a lot of work.

Update 2:

GPE for singularity is -GMm/r. Under general relativity, the radius of a singularity is infinitesimal. Thus, GPE is infinite. However, classical physics doesn’t work smaller than the Planck length so it is unknown whether a black hole’s singularity has infinite GPE. But hypothetically speaking, I believe what I’m asking just may be possible.

Update 3:

Neb

I know mass is an invariant. But the more work is done to a free body, the more energy is transferred to it. Because energy has mass, according to e=mc squared, this must mean that the object has mass, (not matter), added to it by the energy transferred by work done. It’s often stated by top scientists that at the speed of light, mass is infinite just as it’s often stated that at the speed of light, time is infinitely dilated or space is infinitesimally contracted. Thats a way of saying it…

Update 4:

…dividing by zero yields both infinity and negative infinity, together. Thus, yes it is undefined, but it also infinite, (and negatively infinite).

Update 5:

I bring up tachyons and time travel because going faster than light results in backwards time travel. So if something in one black hole is encompassed by another larger black holes singularity, it would have infinite GPE. If this so happened to be enough energy to cause that object to move faster than light, it’d go back in time like a tachyon. But this isn’t possible because even at a singularity, GPE is infinite. Faster than light travel requires greater than infinite energy. Thus, it is stuck

Update 6:

Plus, although the Planck length may not be the smallest possible length, it is the smallest length of which classical physics still operates. Anything smaller than this length, classical physics doesn’t apply anymore. Thus, GPE couldn’t be defined as GMm/r anymore. Energy couldn’t even be defined the same anymore.

Update 7:

Neb are you saying energy doesn’t have mass?

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• Anonymous
1 month ago

Not if you are flying in a tachyon rocket

• 1 month ago

see asteron X on you tube,we MAY  acquire means to bypass einsteins equation where infinite energy is required for travel at C ,( V= 300k Km.sec) by,,creating a time;space bubble in/on which to  traverse vast galactic distances,as an enginless ocean traveling boat may ride wavecrests which  propel the thing over great distances,or a surfer inside a wave pipeline,,asteron dude goes into considerable pages of formulae,equations,ways to impart zero mass to the conveying vehicle,vastly reducing the energy necessary to attain FTL V,,the key is understanding space/time envelopes  citations from miguel alcubierre are there,supported by  another egghead whose math shows methods to produce zero mass/

• ?
Lv 7
1 month ago

Well Hypothetically infinite and singularity contradict each other

You are right, we need a new way to think

Cosmically we are still in the Stone Age

Something will come along

Try studying Quantum Entanglement and it may blow your mind !

Source(s): All from your own Armchair
• ?
Lv 7
1 month ago

Couple of conceptual points ....

Mass is an invariant in relativity. It does not increase with velocity. The γ factor comes from the time dilation in components of 4-velocity (e.g. Ut = ∂(ct/∂τ) = (∂(ct)/∂t)(∂t/∂τ) = γc) which is used to derive Einstein’s energy-momentum equation.

Energy of material particles does not become infinite at the speed of light - it becomes undefined. Reference frames and Lorentz  transformations don’t exist at v=c.

Gravitational energy of black holes is not infinite. Curvature approaches infinity but is undefined at r=0 for a classical Schwarzschild black hole.

I have absolutely no idea why you bring up tachyons and time travel.

mγc^2 is relativistic energy. It is not mass and should not be treated as mass. There is only one kind of mass and that is rest mass. And no, top scientists do not say that mass becomes infinite (or they are not top scientists), nor do they say time dilates to zero and length dilates to zero. Light DOES NOT HAVE A REFERENCE FRAME. And dividing by zero does not mean it’s both infinity and negative infinity. It means it’s NOT DEFINED and does not physically apply. We can (and do) conclude that light take the null ( ds^2 = 0) path in all frames but that’s all we can conclude. Physicists don’t consider the null path a measure of proper time for ‘light’ for above reasons.

Black holes can and do merge - recent detection of gravitational waves prove that - you simply get a larger black hole plus gravitational waves. Nothing requires infinite PE or anything else to prevent escape. The event horizon of a black hole - any black hole - is a null surface. That simply means anything within that surface requires a space-like path to get out with respect to that surface. Nothing to do with infinite PE which you are using classical Newtonian PE anyway (gravitational energy - in fact any energy - is a very complex topic in general relativity).

Again, regarding the singularity, the best you can do is say that curvature invariants approach infinity as r approaches zero (for a Schwarzschild black hole). Those curvature invariants are undefined at r=0. Energy cannot be characterized at r=0. That’s one of the reasons the Schwarzschild solution is a vacuum solution - the stress energy can’t be defined at r=0 for a singularity.

I would really encourage you to just ask a question rather than pose what you think is an answer.....

Update: No, I’m saying energy and rest mass are different. You can CONVERT between the two via various physical processes, but they are not the same thing. For instance, the relativistic kinetic energy of a Hadron at the LHC can ultimately result in particles being created with rest masses that have been converted from the relativistic kinetic energy. But you certainly wouldn’t say that relativistic kinetic energy is the same thing as rest mass.

• 1 month ago

Black holes do not have infinite gravitational energy.

• cosmo
Lv 7
1 month ago

The energy of black holes is not infinite.

What energy black holes do have is also negative --- a large negative number.

• Anonymous
1 month ago

The speed of light, as a fluctuation of photon propagation, is the limit of "stretch" allowed in spacetime. A black hole, in some sense, can be thought of as the result of an attempt to go faster than light.

• ?
Lv 6
1 month ago

By the time an object reached the speed of light, Einstein calculated, its mass would be infinite, and so would the amount of energy required to increase its speed. To go beyond the infinite is impossible.

• !
Lv 7
1 month ago

Going faster than light doesnt require infinite energy, its simply impossible under our current understanding of physics. And black holes dont have infinite gravitational energy, just a very high, but still finite, amount

• Anonymous
1 month ago

things cannot go faster than light