# B Could you travel using nuclear bombs?

#### Audun Nilsen

I have two scenarios.

One; imagine that, at the same time as the engine of your ship is ignited, there is also a device detonated inside the ship. If timed correctly, the difference between the two would equal out, right? For now, there's one huge problem and that's making sure the aim is correct, because, if you collide with an asteroid or something, you'd just spin out of control, but if you could measure the trajectory perfectly, there would be nothing in the way of that, if space, truly, is a vacuum which could accommodate fast travel. Next, there's the slowing down. Once the blast has burned out, you would naturally slow down, but the process of slowing down an object from something in the area of the speed of light would take immensely long, but you can calculate how long you go by adjusting the strength of the device according to distance. If there is some kind of resistance in space, fine, and if not, you can fire an engine in the nose end of the ship and initiate the stopping sequence that way. If there is only miniscule mass the stopping force would have to be on a par with the start force, and, again, if you detonate outside and inside at exaclty the same time, then you won't have a problem, right? Relative to ... the sides of the "ship", your pod hasn't moved at all. In short, dead accuracy is the way to go.

Two; imagine a huge construction with several hundred stories of tunnels with rails in them, which all contained a smaller pod except the one in which you have the astronauts, and imagine also that the pods of this Matryoshka ship has springs in both ends and, when the ship speeds up or slows down, the springs lessen the impact, and reduce G-forces to an acceptable minimum. The challenge as I see it here, is not just accuracy, but sheer size, since the force of, even, a jet engine in a vacuum would be immense and, so, you'd need 100s, maybe 1.000s of pods. I'm sure that having vacuum inside the tunnels would help, since that would lessen the immediate impact, but it would make the length of the tunnels a great deal bigger.

Related General Physics News on Phys.org

#### davenn

Gold Member
Hi there
welcome to PF

Next, there's the slowing down.

do you know why the spaceship would slow down ?

but the process of slowing down an object from something in the area of the speed of light would take immensely long,

did you know that nothing with mass can travel at the speed of light ?

#### Audun Nilsen

Even if you didn't have enough plasma to stop a spaceship, you could use athmospheres of all kinds, going tipsy-turvy around a solar system until you make it; that would be a virtuose feat of accuracy, but theoretically feasible; and

what's to say that light isn't an expression of mass, just like electricity? Electricity is electrons jumping from atom to atom, so why would it be any different with light? Isn't that what you school buds call photons?

#### anorlunda

Mentor
This is not quite what the OP described, but it is lots of fun.

https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion) said:
Project Orion was a study of a spacecraft intended to be directly propelled by a series of explosions of atomic bombs behind the craft (nuclear pulse propulsion). Early versions of this vehicle were proposed to take off from the ground with significant associated nuclear fallout; later versions were presented for use only in space. Six tests were launched[

#### Audun Nilsen

Wicked!

I did some calculations :P and found that you could get more than the speed of light with a Tsar Bomb:

50 megatons is 4.8 B stronger than jet fuel.

Staff Emeritus
I did some calculations :P and found that you could get more than the speed of light with a Tsar Bomb
Unfortunately, not correct calculations.

#### anorlunda

Mentor
Truth is stranger than fiction.

Also from that Project Orion Wikipedia article.
A test that was similar to the test of a pusher plate occurred as an accidental side effect of a nuclear containment test called "Pascal-B" conducted on 27 August 1957.[34] The test's experimental designer Dr. Robert Brownlee performed a highly approximate calculation that suggested that the low-yield nuclear explosive would accelerate the massive (900 kg) steel capping plate to six times escape velocity.[35] The plate was never found but Dr. Brownlee believes that the plate never left the atmosphere, for example it could have been vaporized by compression heating of the atmosphere due to its high speed. The calculated velocity was interesting enough that the crew trained a high-speed camera on the plate which, unfortunately, only appeared in one frame indicating a very high lower bound for the speed of the plate.

#### Audun Nilsen

Feel free to endulge us. I used an energy converter I found online.

#### Audun Nilsen

It said the theoretical top speed was about 10%. That's what I came to when I compared the energy density of a reactor with jet fuel.

#### hutchphd

This is not quite what the OP described, but it is lots of fun.
Great footage and Freeman Dyson and TheodoreTaylor:

#### davenn

Gold Member
what's to say that light isn't an expression of mass, just like electricity?
It isn't .... please don't make things up .... the fundamentals of Electromagnetic radiation is very well known

Isn't that what you school buds call photons?

Photons are quantum packets of energy they are not little bullets/particles shooting along

Staff Emeritus
Feel free to endulge us.
I don't know what you mean.

I used an energy converter I found online.
And. they wouldn't put it on the internet if it wasn't true?

You have to decide if you are here to ask us things or tell us things. You seem to be wanting to tell us things. Unfortunately, those things are not correct.

#### Janus

Staff Emeritus
Gold Member
Wicked!

I did some calculations :P and found that you could get more than the speed of light with a Tsar Bomb:

50 megatons is 4.8 B stronger than jet fuel.
I'm afraid your calculations have misled you.
50 mt = 2.1e17 joules. Using the Newtonian expression for kinetic energy
$$E = \frac{mv^2}{2}$$
And assuming a mass of 1000 kg ( about that of a small car)
we can rearrange and solve for v, which would be the velocity one could reach using 2.1e17 joules of energy to accelerate 1000 kg up to v
The answer comes out to be just a bit under 7% of the speed of light.
So the Tsar bomb, even if you could convert all it its explosive energy to kinetic energy in the 1000 kg mass, comes way short of the speed of light.

Not only that, but the Newtonian expression for KE turns out to only give a reasonably accurate answer for values of v that are small when compared to the speed of light.
The more accurate equation is
$$KE =mc^2 \left ( \frac {1}{\sqrt{1-\frac{v^2}{c^2}}} -1 \right )$$

With this equation, as v approaches the speed of light (c), KE increases without limit. The upshot is that, no matter how much energy you have available, you will always come up short of getting any mass up even up to the speed of light.

#### anorlunda

Mentor
The OP will not be returning to this thread,.

"Could you travel using nuclear bombs?"

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving