Faster than c?

@Akbar2thegreat
I have been saying from a long time still... such particles are hypothetical even if they existed they would create time travel paradoxes. Watch this "can we go faster than the speed of light" ... m_youtube_com/watch?v=vVKFBaaL4uM (i seem to be facing problem sending links just replace _ with .) ... if you watch this ignore the last neutrinos cant move faster than light as said by @Thalassokrator.

You are disobeying Albert Einstein 's special relativity (now he will be angry Xb JK) by saying particles/object can travel faster than light. A particle accelerator can move a particle 4m/s slower than C . If you somehow move a particle faster than light you would somehow need to get infinite energy (dr.strange could help you harness a finite amount of energy from multiverse though). light (or any Photon) cant move faster than speed of light. And energy doesn't have speed it just mathematical and physical concept which remains constant (in universe as whole). If you are talking about tachyon it's not real. So no particle or concept known to human can travel faster than light.

A little tip dont stick to one source see as many sources as possible i have seen all of what i say from quora , youtube , multiple trusted sources on google.

@UtkarshPKumar said in #40:

Thanks for that i used to believe its still under debate or under process of checking errors in the experiment or something.

No problem :-)

Again thanks for the relative velocity formula. In books (of school) we are just given with definition and least possible formulas (i hope its the case for only pre 9th standards) so i thought of this at a smaller scale (a car and a man going in different direction) i concluded it as the right formula for finding relative velocities (lol).

u = v + u' is the correct formula for low speeds, so it's not wrong per se! :-)
It's just a special case (an approximation) of the relativistic u = (v + u')/(1+(vu')/c^2) for v and u' much smaller than c. If both speeds are slow the term in the denominator 1+(vu')/c^2 becomes nearly equal to 1. Because (v*u')/c^2 ≈ 0 for both v and u' much smaller than c.

The next part of the formula ((1+v*u')/c^2) do anything with the light coming to us (the observer) from the object so it doesn't become faster than light?

The term in the denominator is (1 + (vu')/c^2). As both v and u' go towards c, this term approaches 1+ (c^2)/(c^2) = 1 + 1 = 2. So as both speeds go towards c, the denominator approaches 2. Therefore the whole term u = (v + u')/(1+(vu')/c^2) goes to (c + c)/2 as both speed go towards c. The relative speed of two objects approaching the speed of light (in opposite directions) still only approaches the speed of light.

That's the maths. The physical justification is Einstein's second postulate of special relativity which states that the speed of light should be invariant, independent of the relative motion of the source of emission to the observer. This can indeed be experimentally verified and countless other testable predictions can be made (based off of this postulate) that so far seem to be vindicated by experiment. Special relativity is tried and tested and works phenomenally well.

Wait what so you mean the space is getting stretched (so are the light spectrum and causing red shift) CMBR (cosmic background microwave radiation) became microwave due to streching of space so that means space(as whole) is expanding or is the universe the entire space ?

Yes, space itself is expanding. When people say "the universe is expanding" they mean that the average cosmological distances between all galaxies (with the exception of those gravitationally bound to each other) are increasing due to the metric expansion of space. It might be a bit misleading to talk about the expansion of the universe when all you mean is that distances within the universe are getting bigger.

Is big RIP about the space getting ripped ?

Yes, that's what would ultimately happen in that scenario: https://en.wikipedia.org/wiki/Big_Rip

But that's not what's happening now. Currently space is simply expanding, but this expansion is slow enough for gravity to easily overcome it giving us all sorts of wonderful structures like galaxy clusters, galaxies, stars, planets, comets etc.

It should also be noted that this Big Rip hypothesis for the final fate of the universe is very speculative. It relies on the existence of a hypothetical form of an unknown form of energy. Yeah, talk about a far fetched hypothesis.

And observational evidence also doesn't seem to favour it at the moment, indicating that a Big Rip would happen in the very, very, very far future of our universe (if ever). The relevant parameter w (the ratio between the dark energy pressure and its energy density) is measured to be very close to -1 in our universe (w ≈ −0.991). If w were exactly equal to -1, the Big Rip could never happen. The closer w is to -1, the further in the future the Big Rip would be. Currently observational evidence is not yet precise enough to determine whether or not w is slightly smaller than -1, equal to -1 or slightly larger than -1.

Therefore the Big Rip hypothesis is not yet fully out of the picture, but current knowledge indicates that if this speculative event is ever to occur, it will be extremely far in the future.

For fun I plugged the relevant numbers into the equation given on wikipedia and obtained:
Universe pressureless matter density parameter: Ω_m ≈ 0.3
Hubble parameter: H_0 ≈ 68 km/s/Mpc
w ≈ -0.991

t_rip - t_0 ≈ 2/(3*(1+ (-0.991))*(H_0)sqrt(1 - (Ω_m))) ≈ 4.110^19 s ≈ 1,290,000,000,000 years

So a potential Big Rip would (at the earliest) happen in 1.3 trillion years, a timeframe about 94 times longer than the current age of the universe (which is only about 13.8 billion years since the Big Bang)
https://www.wolframalpha.com/input?i=93.9*%28age+of+the+universe%29

Thanks, all of you... You have all spent so much time... I have not gotten a lot, though.

@Thalassokrator said in #8:
I am especially thankful for your easy mathematical explanation, but I have to ask, what is the <Unit> used for energy?
E=m (gramm?) * c(length/time) ^2 * y (length/time/(lengh/time))

So the unit to measure and describe energy equals
{weight * (lengh/time)^2 * lengh/time?}

What is E_0? Does it mean the energy equals 0? The E_0*y must be 0,right?

Now, quantum things are not understood by me, though, as I maybe just cannot imagine something on two places at the same time...

And afterwards I do not get anything anymore...

@KartikeyaSharma0504 said in #38:

Hey, you missed 'a' in my name. Why everyone miss letter a? And I am learning from my father as well as from YouTube.

Because many think that it is like that. I have a classmate named Kartikeya but even teachers often call him Kartikey.

At first sight of the title, I thought #1 was asking for a programming language faster than c (language).

@Thalassokrator in #42
Big thanks for all those explanation.
As of now i believe in big bounce more than big Bounce more than big RIP (it states how this big bang could have happened and something din't come from nothing)
The formula at last goes above my head. it seems something very advance (and out of the world for me)

@absicht_MAUERzuBAUEN in #43

Thanks, all of you... You have all spent so much time... I have not gotten a lot, though.
Happy to help ... you will eventually get a grasp on it.

I am especially thankful for your easy mathematical explanation, but I have to ask, what is the <Unit> used for energy?
E=m (gramm?) * c(length/time) ^2 * y (length/time/(lengh/time))
In the formula E = γmc^2
E is energy its derived unit is kg * m^2 / s^2 it's SI is Joule you can derive by formula mass * acceleration * meter or another possible way newton * meter. energy is also known as newton meter.
in that γ must be unit-less ,only magnitude quantity, although i am not sure.
Yes, unit of m(mass) is gram but in physics we commonly use Kg as most bodies weigh much more so most equation use kg and not gram

So the unit to measure and describe energy equals
{weight * (lengh/time)^2 * lengh/time?}
Yes you are correct. When we substitute these values with there units and simplify we get :
kg * m^2 / s^2

@absicht_MAUERzuBAUEN said in #43:

I am especially thankful for your easy mathematical explanation, but I have to ask, what is the <Unit> used for energy?
E=m (gramm?) * c(length/time) ^2 * y (length/time/(lengh/time))

So the unit to measure and describe energy equals
{weight * (lengh/time)^2 * lengh/time?}

My pleasure! Physics rambling incoming:

The formula is E = γmc^2

Let's do so called "dimensional analysis" to find the units:
[E] = [γ][m][c]^2

Here square brackets denote the dimension (or unit) of the parameter. The Lorentz factor γ (denoted by the greek lower case letter gamma) is said to be "dimensionless". Fancy word, but it means nothing more that it has no unit. It's simply some number.
If v is 99.5% of the speed of light for instance, the Lorentz factor is the number 10.

Returning to the units we can write:
[γ] = 1

Why? Because all units cancel out in the formula for γ:
γ = 1/(√(1 - (v/c)^2))

Let's focus in on the v/c bit (as the rest of the formula for γ already are numbers without units). That's a speed (that of the object) divided by the speed of light. Both have units of length divided by time, but that isn't really important. It's enough to observe that both have the same units, therefore the units cancel out when you divide one by the other:

[v/c] = [v]/[c] = (L/T)/(L/T) = 1

You can treat units in the same way as you treat numbers. When you have the fraction 15/25, you know that you cancel the common factor 5 in the numerator and the denominator: 15/25 = (53)/(55) = (5/5)(3/5) = 1(3/5) = 3/5

In the same way you can cancel units of length (denoted by L) in the numerator with units of length in the denominator.

Let's look at mass next: It has, well, units of mass (like the kilogram for example):
[m] = M

The speed of light has units of length divided by time (meters per second for example):

[c] = L/T

Therefore energy has units of mass times units of length squared divided by units of time squared:
[E] = M*(L^2)/(T^2)

I've done this in the most general way possible, that way you can choose which practical units you want to measure in. You could choose the metric system, using the kilogram (kg) as a unit of mass M, the metre (m) as a unit for length L and the second (s) as a unit for time T.

In the metric system energy has units of kg*(m^2)/(s^2), spoken as "kilogram square metre per square second". This is a bit of a mouthful and therefore physicists have defined the derived unit of energy called the Joule (J), which is exactly that:

1 J = 1 kg*(m^2)/(s^2)

When measuring electric energy, you often don't use the Joule itself, but another derived unit, the kilowatt-hour (kWh). The watt is the unit of power (energy per unit time): 1 W = 1 J/s (Joule per second)
The k in kWh means the prefix kilo- (a factor 1000). And an hour has 60 minutes with 60 seconds each. So:
1 kWh = (1000 J/s)(6060 s) = 3,600,000 J

This unit (the kWh) is more convenient because the power drawn by electrical home appliances (washing machine, fridge, computer, etc.) is usually given in Watts or kilowatt. So you can easily calculate how many hours you can run them if you only want to pay for x kilowatt-hours.

Other unit systems exist (like the cgs system, which uses grams instead of kilograms for mass and centimetres instead of metres for length) and are helpful in certain contexts (like electromagnetism).

In particle physics Einstein's E_0 = m*c^2 is used to measure rest masses in terms of the associated energy (divided by the speed of light squared). So the rest mass of a proton would be given as

m_p ≈ 938.3 MeV/c^2 (megaelectronvolts per speed of light squared),

where 1 MeV is 1,000,000 times the kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt (1 V) in vacuum. You see, units can get really weird, really fast. The MeV/c^2 is a useful unit for particle masses though :-)

In the metric system you would give the mass of a single proton as m_p ≈ 1.6726*10^(-27) kg (kilograms), which looks a lot uglier (to physicists) than 938.3 MeV/c^2 does, because the kilogram is a unit invented to measure tangible things commonly found around humans like other humans, a sack of potatoes or some piece of furniture. The kilogram is not designed to measure the incredibly tiny mass of individual protons, which is why you need to add the unimaginable 10^(-27) factor, i.e. 0.000000000000000000000000001, when you try to measure the proton mass in kilograms.
The MeV/c^2 however it up to the job. I was designed with elementary particles (namely electrons) in mind.

There's also the system of customary units in the US, which still uses units defined by some English king in the middle ages on the basis of the length of a barley corn (and other things intuitively accessible to the people of the time). They use feet (ft) for length, pound (lb) for mass, etc.
This system of measurement still has its uses (interpreting cooking recipes for example), but it's not designed for science and engineering which is why in the US, military, spaceflight, engineering, scientific research, etc. has largely switched over to the metric system (at least under the hood).

Sorry, I went on a long tangent there. Bottom line is: The most sensible unit for (kinetic) energy of common objects (like a baseball flying through the air or a plate falling to the floor) is the Joule. Other than that, there are many energy units which are more convenient in certain contexts.

What is E_0? Does it mean the energy equals 0? The E_0*y must be 0,right?

No, it's not equal to 0 (for objects with nonzero mass). Sorry for the confusion.
It's my way to write E with a subscript 0. This is often done to denote the base state (lowest energy state) of a system. In this case, it means the rest energy of the object. Rest energy is the energy that is intrinsic to the object, it's there even if the object isn't moving at all.
I did this in order to differentiate it from the total energy of the object E (which includes its kinetic energy, i.e. energy of motion).

1 kg of motionless matter (be it gold or carbon or water or milk or whatever) always has the same amount of rest energy E_0. You can calculate this intrinsic energy via Einstein's famous E_0 = mc^2.
If we plug in m = 1 kg and c^2 ≈ 910^16 (m/s)^2, we obtain a rest energy of

E_0 ≈ 9*10^16 J = 90000 TJ (terajoule)
You might be familiar with the prefix tera- from your computer (1 TB = 1000 GB of memory).
This is an enormous amount of energy. It's equivalent to 21.5 million tons of TNT explosives. In a single kilogram of matter (a litre of milk for example)!
And indeed this is the principle that allows nuclear weapons to be so destructive. A small amount of matter (only a few hundreds of kilograms) is fully converted into energy during the explosion of a nuclear weapon. Luckily you need some pretty extreme conditions (fissionable material being bombarded by high energy neutrons for example) to get this nuclear reaction going, so you don't need to worry about your litre of milk spontaneously blowing you and your entire city to smithereens. It's perfectly stable and won't blow up.

The "dragon" is there (yes, even in your can of milk), but it is sleeping deeply. I sincerely hope we humans will never again waken the nuclear dragon.

@UtkarshPKumar said in #46:

@Thalassokrator in #42
Big thanks for all those explanation.
As of now i believe in big bounce more than big Bounce more than big RIP (it states how this big bang could have happened and something din't come from nothing)
The formula at last goes above my head. it seems something very advance (and out of the world for me)

It goes over my head as well. I have no clue how they derived this formula. One pretty much needs to be a professional research cosmologist to understand this stuff fully, so don't beat yourself up :-)

@Thalassokrator said in #7:

There are to my knowledge no massive (mass greater than zero) objects which have been found to travel through space at speeds exceeding (or merely equalling) c. Could you point me towards a source so that I know what you're talking about? Thanks!

What about the theoretical negative mass? A guy once explained that it can be substituted to formulas and it accelerates to the opposite of the force something? How would it look nevertheless.

@Zinner_Override said in #49:

What about the theoretical negative mass? A guy once explained that it can be substituted to formulas and it accelerates to the opposite of the force something? How would it look nevertheless.

The guy was bullshitting you.
Universe says C. THE END.